User manual | U-Pb geochronology of the southern Scandinavian Caledonides: the Mesoproterozoic Espedalen anorthosite-gabbro

Goldschmidt Conference Abstracts
Low-temperature Pt–Pd
mineralisation: Examples from Brazil
Iodine fingerprints biogenic fixation
of platinum and palladium
A.R. CABRAL1*, B. LEHMANN1 AND M. BRAUNS2
Mineral Deposits, TU Clausthal, 38678 Clausthal-Zellerfeld,
Germany
(*correspondence: [email protected])
2
Curt-Engelhorn-Zentrum Archäometrie, 68159 Mannheim,
Germany
A.R. CABRAL1*, M. RADTKE2, F. MUNNIK3,
B. LEHMANN1, U. REINHOLZ2, H. RIESEMEIER2,
M. TUPINAMBÁ4 AND R. KWITKO-RIBEIRO5
1
Hematite-bearing Au–Pd mineralisation in Brazil
commonly has a platiniferous component [1, 2]. Examples are
Hg-bearing hongshiite, PtCu, and Pt2HgSe3, both from Itabira,
Minas Gerais. These minerals occur in specular hematite-rich
veins that cross-cut the ~0.6-Ga Brasiliano tectonic foliation
of the host rock (itabirite). This vein mineralisation is called
‘jacutinga’. The presence of barite in hongshiite and Na/K–
Na/Li fluid–mineral geothermometers indicate that oxidising
brines of evaporitic origin were instrumental to the Au–Pd–Pt
mineralisation at a maximum temperature of about 350°C [3].
Platiniferous alluvia are found in the quartzitic domains of
the Palaeo-Mesoproterozoic southern Serra do Espinhaço,
Minas Gerais, north of Itabira. Alluvial palladiferous gold and
specular hematite point to ‘jacutinga’-like veins in the
quartzite country rock in the Córrego Bom Sucesso area. We
found high Pd/Ag ratios (~4–3700) in the alluvial
palladiferous gold. Such ratios are thermodynamically
restricted to very oxidising brines [4]. In addition, Córrego
Bom Sucesso is famous for its botryoidal Pt–Pd aggregates,
reaching several millimetres across, which formed within the
alluvium [1, 2, 5].
In northern Brazil, Au–Pd–Pt bonanza mineralisation
triggered the gold rush that made Serra Pelada known
worldwide. The near-surface mineralisation is hosted by
weakly metamorphosed metasedimentary rocks of supposedly
Neoarchaean age, but the bonanza ore is coeval with a Mn–Ba
oxide, which has a Late Cretaceous 40Ar/39Ar age [6]. Fluidinclusion microthermometric data from quartz and the mineral
assemblage of Mn–Ba oxide and fine-grained specular
hematite give evidence for very oxidising brines at
temperatures between ~100 and 170°C.
[1] Hussak (1904) Sitz.-Ber. math.-naturwiss. Kl. Kais. Akad.
Wiss. 113, 379-466. [2] Cabral et al. (2009) Econ. Geol. 104,
1265-1276. [3] Lüders et al. (2005) Miner. Deposita 40, 289306. [4] Gammons et al. (1993) Geochim. Cosmochim. Acta
57, 2469-2479. [5] Cabral et al. (2011) Chem. Geol. 281, 125132. [6] Cabral et al. (2011) Econ. Geol. 106, 119-125.
Mineralogical Magazine
609
Mineral Deposits, TU Clausthal, 38678 Clausthal-Zellerfeld,
Germany
(*correspondence: [email protected])
2
BAM Federal Institute for Materials Research and Testing,
12489 Berlin, Germany
3
Institute of Ion Beam Physics and Materials Research,
HZDR, P.O. Box 510119, 01314 Dresden, Germany
4
Faculdade de Geologia, UERJ, 20550-050 Rio Janeiro-RJ,
Brazil
4
Centro de Desenvolvimento Mineral, VALE, Caixa Postal 09,
33030-970 Santa Luzia-MG, Brazil
1
Botryoidal aggregates of platinum (Pt) and palladium (Pd)
from an alluvial deposit (Córrego Bom Sucesso) in Serro,
Minas Gerais, Brazil, were likely the sample material from
which Wollaston [1] isolated and identified Pd for the first
time [2]. We recovered millimetre-sized botryoidal and rodshaped grains of Pt and Pd from the alluvial deposit. Their
arborescent morphologies indicate that the Pt–Pd aggregates
formed in situ within the alluvium [2]. We carried out
synchrotron radiation-induced X-ray fluorescence (SR-XRF)
spectrometry on the Pt–Pd aggregates to determine iodine. We
found high concentrations of iodine, in the range from 10 to
~120 !g/g [3]. Iodine is a strongly biophile element [4], which
is enriched in peatlands by microbial activity [5]. Its high
concentration in the Pt–Pd nuggets suggests that microbial
activity took place during precious-metal fixation in the
aqueous alluvial milieu. The Pt–Pd nuggets have an average
thallium/selenium ratio of about 0.08, a value close to that for
fluvial waters, suggesting that Pt and Pd were fixed from
highly dilute solutions within the alluvium [6]. Inorganic and
biogenic processes, i.e. electrochemical metal accretion [7]
and bioreduction, are thought to have contributed to the
growth of biogenic Pt–Pd nanoparticles that formed on
organic templates such as humified plant remains.
[1] Wollaston (1809) Phil. Trans. 99, 189-194. [2] Hussak
(1906) Z. prakt. Geol. 14, 284-93. [3] Cabral et al. (2011)
Chem. Geol. 281, 125-132. [4] Goldschmidt (1958)
Geochemistry. Oxford University Press. [5] Keppler et al.
(2004) Environ. Chem. Lett. 1, 219-223. [6] Cabral et al.
(2009) Econ. Geol. 104, 1265-1276. [7] Cabral et al. (2009)
Eur. J. Mineral. 21, 811-816.
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610
Goldschmidt Conference Abstracts
Volatile and trace element
abundances in HIMU melt inclusions
Mineralogy of stream sediments and
soils of Santiago Island, Cape Verde
R.A. CABRAL1*, M.G. JACKSON1, E.F. ROSE-KOGA2,
J.M.D. DAY3AND N. SHIMIZU4
Department of Earth Sciences, Boston University, Boston,
MA 02215, USA (*correspondence: [email protected])
2
Laboratoire Magmas et Volcans, Universite Blaise Pascal,
CNRS, UMR 6524, IRD, R 163, Clermont-Ferrand,
France
3
Scripps Institution of Oceanography, La Jolla, CA 92037,
USA
4
Woods Hole Institute of Oceanography, Woods Hole, MA
02543, USA
1
Water distribution within the mantle influences magma
chemistry and evolution, location and extent of melting, and
volcanism over geological time. During subduction, oceanic
crust has been suggested to transport significant quantities of
water and other volatiles to post-arc depths [1]. Despite the
important control water has over mantle characteristics and
behavior, the amount of water that is retained within the
descending slab is poorly constrained [2, 3].
One possible method for constraining the amount of
surviving volatiles is to examine oceanic hotspot lavas that are
thought to sample melts of subducted oceanic crust. It is
hypothesized that subducted material can be returned to the
shallow mantle in areas of mantle upwelling, where it is
partially melted and erupted during hotspot volcanism. Lavas
from Mangaia represent the HIMU (high-µ, or high
238 204
U/ Pb) mantle end member, which contains geochemical
signatures associated with recycled oceanic crust.
Earlier work on olivine-hosted melt inclusions from
Mangaia found the inclusions to host volatile-rich phases (e.g.,
amphibole, phlogopite, apatite, and carbonatite [4]), an
observation that is consistent with Mangaian melt inclusions
being volatile-rich. High volatile abundances, coupled with
major- and trace-element compositions in melt inclusions that
are consistent with HIMU source derivation, may indicate that
subducted oceanic crust has retained a significant amount of
water [1]. This would imply that dehydration during
subduction of oceanic crust is not an efficient process.
Here, we will place new constraints on deep cycling of
volatiles into the mantle through examination of olivinehosted melt inclusions, and we will present the first ever
volatiles data on HIMU end member glasses.
M.M.S. CABRAL PINTO1,2*, M.M.V. SILVA2,
R. HERNANDEZ1 AND E.A. FERREIRA DA SILVA1
1
2
Geobiotec Center, University of Aveiro, Portugal
Geociences Center, University of Coimbra, Portugal
(*[email protected])
Santiago Island covers an area of 991 km2 and is
characterized by a rough relief. (up to 1392 m) and valleys
with almost vertical slopes and large flat areas in the coastal
zones. The climate is semi-arid, with torrential rains. The
lavas occupy most of the island, the pyroclasts are
subordinated and the quaternary sedimentary cover occurs in
small areas. The mineralogical composition of the 70 stream
sediments and 70 soil samples, collected from all geological
formations of the island, was studied in the < 2mm fraction.
The samples are dominated by primary silicate minerals, such
as feldspar (15.0 to 35.4 %), pyroxene (7.8 to 37.4 %) and
olivine (0.0 to 9.0 %), reflecting the mineralogical signature of
the igneous rocks that support the island. Quartz,
phyllosilicates (smectite, kaolinite, mica/illite), calcite,
hematite,
leucite,
apatite,
nepheline,
magnetite,
titanomagnetite, ilmenite, chromite, garnet, zeolites, siderite,
opal, barite, titanite, zircon, halite, aragonite, dolomite, brucite
larnite and chlorite were also identified. Higher proportion of
feldspar and pyroxene were detected on stream sediments
(27.3 % and 25.6 %, respectively), than the soils (24.1 % and
17.0 %, respectively). The soils have higher relative
proportion of quartz (24.5 %), phyllosilicates (16.1 %), calcite
(2.8 %) and hematite (9.6 %) than stream sediments (12.2 %,
14.5 %, 0.8 % and 9.0 %, respectively). These differences are
due to pedogenetic processes and wind-transported materials
that affect the soils. Soil and stream sediments that cover
formations affected by intense weathering are enriched in
phyllosilicates and hematite and impoverished in pyroxene
and olivine.
[1] Hacker (2008) G3 9, doi:10.1029/2007GC001707.
[2] Hilton et al. (2002) Rev.Miner 47, 319-370. [3] Wallace
(2005) Volcan.Geotherm.Res. 140, 217-240. [4] Saal et. al.
(1998) Science 282, 1481-1484.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Contrasting mechanisms for two
pulses of garnet growth at Stillup Tal,
Tauern Window, Austria
MARK J. CADDICK1 , ETHAN F. BAXTER1,2 AND
ANTHONY D. POLLINGTON2,3
ETH Zürich, 8092 Zürich, Switzerland
Boston University, Boston MA, 02215, USA
3
University of Wisconsin, Madison, WI, 53706, USA
1
2
Growth of ca. 110 cm3 sub-spherical garnet crystals in a
shear zone in the Austrian Tauern Window required
ca. 7.5 Myrs, with the vast majority of this growth occurring
in two distinct pulses [1]. These pulses are characterised by
growth rates at least 5 times higher than the ‘ambient’ rate
experienced during the ca. 2 Myr inter-pulse hiatus, and
during the final stages of crystal growth. Here we explore
possible mechanisms for such short crystal growth bursts,
testing their viability in terms of an Alpine history, and using
the available constraints to calibrate an exhumation velocity.
The first growth pulse occurred early in the preserved
garnet history (inner 2 cm diameter of the crystal core) and is
well resolved to no more than a few hundred thousand years
duration (likely much less). A thermodynamically constrained
garnet growth model [2] and a complex suite of mineral
inclusions suggest that this records growth over a relatively
limited range of P and T, at > 35 km depth and temperatures
several 10s of degrees above the garnet-in reaction. A sharp
Mn decrease within this growth phase likely reflects Rayleigh
fractionation, but otherwise both garnet composition and its
mineral inclusion assemblage are effectively constant. This
supports the hypothesis that a kinetic trigger initiated and
accelerated garnet growth at this time, with a distinct network
of radiating fluid inclusions (absent outside the crystal core)
attesting to fluid abundance [1].
A second phase of accelerated growth is more poorly
resolved to no more than 1.5 million years (again, probably
much less). Characteristic changes in all measured divalent
cations imply that both this rapid crystal overgrowth and the
slowly-grown crystal segment that preceeded it grew during
ca. 5 kbars decompression and 50-100 ˚C heating. Results are
consistent with equilibrium growth along a P-T trajectory that
traversed fields of relatively constant mineral assemblage and
then intersected a set of mineral reactions that accelerated
garnet growth. Both slow garnet growth after the first pulse
and rapid growth in the second pulse are thus possible without
recourse to additional kinetic mechanisms or substantial
increases in heating or decompression rate.
[1] Pollington & Baxter (2010) EPSL. 293. 63-71. [2] Caddick
et al. (2010) J. Pet. 51. 2327-2347.
Mineralogical Magazine
611
The characteristics of organic matter
adsorbed on clay minerals and its
significance in carbon cycling
CAI JINGGONG1*, JI JUNFENG2, LU LONGFEI1, DING FEI1
2
AND CAI YUANFENG
State key laboratory of marine geology, Shanghai, 200092,
China (*correspondence: [email protected])
2
State Key Laboratory of Mineral Deposits Research, Nanjing;
210093,china
1
The protection of organic matter (OM) via adsorption on
clay minerals is well recognized in recent years, however, the
quantity and occurrence of OM adsorbed on different kinds of
clay minerals may be not the same. As a result, smectite and
illite were selected to synthetize with OM which are positive
(HDTMA), negative (SDS) and neutral (0p-10) OM in various
CEC. The amount, stability and occurrence of OM combined
with different kinds of clay minerals were studied and their
evolution distinction in the carbon cycling was discussed as
well.
The result shows that the total organic carbon (TOC)
absorbed on both the smectite and illite is 5-20%, and
increasing with the CEC. Moreover, the TOC of positive OM
absorbed on the smectie or illite is higher than the other kinds
of OM. After 6 months at room temperature, the TOC
absorbed on semectite decreases slightly(5-20%), whereas the
TOC absorbed on illite decreases sharply to less than 2%. In a
programming heating experiment, the TOC of smectitecomplexes was 7% at the temperature of 300", and decreased
to 2% as the temperature up to 500"; however, the TOC of
illite-complexes decreased to below 2% at 100". These
results suggest that the stability of the complexes combined
with smectite and illite is distinctively different. The
diagnostic peaks of the smectite-complexes, including the
d001 reflection peak on XRD, the methyl vibration peak and
water vibration peak on IR, were changed in a programming
heating, which indicate that the OM was not simply absorbed
on the surface of smectite but also into the interlayer space.
However, the diagnostic peaks of the illite-complexes on XRD
and IR were changed slightly, which indicate that the OM was
simply absorbed on the surface of illite. The different
occurrences of OM associated with smectite and illite must
determine the fate of OM in the evolution, which is significant
in carbon cycling study.
This research was supported by the NSFC (Grants
40872089 and 41072089) and the State Key Lab. of Marine
Geology Fund,Tongji University (MG200902).
www.minersoc.org
612
Goldschmidt Conference Abstracts
Contaminant transport modeling in
the candidate VLLW disposal site
Alteration of arsenopyrite in
sulphruic acid
CAI XINGQI, WANG YONGLI* AND DUO TIANHUI
1
Department of Geochemistry, Chengdu University of
Technology, Sichuan Province
(*correspondence: [email protected],
[email protected], [email protected])
This paper takes advantage of MODFLOW software to
simulate the groundwater pollutant(Sr) migration in the
candidate VLLW disposal site in the Tea ditch and its nearby
living quarters.
Simulation results show that, when the VLLW are dumped
in landfills, there’s no significantly impact on the environment
and the residents living quarters in the south in 200 years.
Meanwhile, we also simulate the condition once this disposal
site leakage occurs. And this suggests, after the leakage 5
years, Besides pollutant concentration observation Well-3
(OW3) not observed in obvious pollutants, the rest two were
observed a evident value of the pollutant concentration, since
then, pollutants spread to the whole proluvial fan gradually,
there’s no doubt that it has a significant influence on the
proluvial fan and the resident nearby.
Mineralogical Magazine
YUANFEGN CAI12 AND XIAOXIAO HU2
State Key Laboratory of Mineral Deposits Research, Dept. of
Earth Sciences, Nanjing University, Nanjing, China
2
Scool of Earth Sciences and Engineering, Nanjing University,
Nanjing, China ([email protected])
1
Arsenic contaminants gives the huge threaten on
humanbeings health and life.
A massive asenopyrite sample was cut into small pieces of
cube with the size of about 3 mm to have a reference shape
and size when studying the leaching process. The leaching is
lasting one month at the temperature of 100, 150, 200, 250 and
300 oC in sulphric acid with the concentration of 1, 0.1 and
0.001M. The arsenopyrite cube and acid was enclosed in a
tefelon tube and wraped with steel vessel. Each cube was
measured in size and weight previous and after the leaching
process. Then, the cube relicit was cut into sections and was
used to carry out morphological observation under both
petrographical microscope and Scanned Electron Microscope
(SEM), surficial chemical element identification with the use
of X-ray Photoelectron Spectroscopy (XPS). And the liquid
lechate was tested by ICP-AES.
Results show that the size of cube keeps almost same but
the weight decrease with increase of the concetration of
sulphruic acid. It suggests that some element was leached out
from the arsenopyrite. The majority of arsenic is present in the
liquid leachate. The XPS measurement from both surface and
profile shows the signal of As disappeared or weakened after
the leaching process by XPS, while its signal increased with
the in crease of etching time when depth profile scan is carried
out. The morphological obervations gives the fact that the
leaching starts from the outmost surface of cube or the edge of
cracks, large quantities of pores present in the product area,
the boundary of product and arsenopyrite is distinct and sharp,
no buffer area is present, and the relicit keeps the shape of
cube.
Our study shows that the leaching process of arsenopyrite
is controled by the coupled dissolution-precipitation process.
The As ion was leaching out and the new product, most
probable arsenic oxide, precipitated on the surface of cube or
along the cracks. This may suggest that the contamination of
suface water and groundwater from weathering of arsenopyrite
or arsenic pyrite or other arsenic mineral is main geological
cause, And it will bring the huge threaten to the crops,
habitants and long tern side-effect to the biosphere.
Acknowledgements: This work was financially supported
by the NSFC project (40872035)
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Goldschmidt Conference Abstracts
Molecular scale origin of nuclear
waste glass properties
G. CALAS1, L. CORMIER1, J.M. DELAYE2, L. GALOISY1,
P. JOLLIVET2 AND S. PEUGET2
Institut de Minéralogie et de Physique des Milieux
Condensés, UPMC; Université Paris 7; CNRS; 4, Place
Jussieu, 75 Paris, France ([email protected])
2
CEA Valrhô-Marcoule, DEN/DTCD/SECM, BP17171,
30207 Bagnols-sur-Cèze cedex, France
([email protected])
1
Assessing the long-term behavior of nuclear waste glasses
implies predict their performance, and more precisely their
evolution under irradiation and during interaction with water.
Structure-property relationships depending on the local and
medium-range structure of borosilicate glasses of nuclear
interest [1] exemplify structural features rationalizing
properties observed during glass elaboration or under forcing
conditions (alteration, irradiation). Structural data are
correlated with numerical simulations to determine the local
structure of glasses, with a special attention to the interplay
between glass components [2]. During alteration, some
elements, such as Fe, change coordination, as other such as Zr
only change coordination in under-saturated conditions. This
may explain the chemical dependence of the initial alteration
rate and the transition to the residual regime, illustrating the
molecular-scale processes during glass-to-gel transformation
[3]. Determining molecular scale processes helps in the
exploration of new compositions of nuclear glasses [4].
Under irradiation, various structural effects are observed,
including coordination change, ion migration or disorder
effects. These studies show that glasses with a simplified
composition do not show the same behavior as more realistic
glasses. Molecular dynamics (MD) simulations provide
complementary information on elastic effects [5]. Recent
direct evidence for B-coordination change under external
irradiation, together with structural models derived from MD,
sheds light on the structural mechanisms at the origin of
radiation-induced modifications of glass properties,
emphasizing the importance of the thermal regime in the
cascade core. Molecular scale view of nuclear glasses provides
a unifying view of the processes that define the properties of
this important class of materials.
[1] G. Calas et al. (1982) C. R. Chimie 5, 831–843. [2] L.
Cormier et al. (2000) Phys. Rev. B 61, 14495-14499. [3] E.
Pelegrin et al. (2010) J. Non Cryst. Solids 356, 2497-2508.
[4] B. Bergeron et al. (2010) J. Non Cryst. Solids 356, 23152322. [5] G. Bureau et al. (2008) Nucl. Instr. Meth. Phys. B
266, 2707-2710.
Mineralogical Magazine
613
Occurrences of nickel in different
host phases of a laterite deposit:
An example from Berong, Philippines
M.Y. CALIBO*, C.A. ARCILLA, R.M. ONG,
M.L.G. TEJADA AND J.P. RAFOLS
National Institute of Geological Sciences, University of the
Philippines – Diliman, Quezon City, 1101 Philippines
(*correspondence: [email protected])
Despite being globally widespread and relatively easy to
mine, nickel laterite ores prove to be difficult to process.
Beneficiation of Ni and other economically extractable
elements along with it, greatly depends on the mixture of the
feed material (silicate phases and oxide phases) which, in turn,
is dependent on the mineralogy of the raw ore. The type(s),
concentration and consumption of acid to be used in
dissolution are controlled by the percentages of both gangue
and host minerals trapping the Ni, whether by sorption or
isomorphous substitution. A modified selective sequential
extraction was designed to recover Ni from from its various
host phases to optimize the beneficiation process using
samples from different zones in a nickel laterite deposit in
Berong, Palawan. This deposit is defined by, from top to
bottom, an iron oxide-hydroxide zone, a transition zone made
up of serpentine and iron oxides, a nickel-enriched serpentine
zone, and a nickel-depleted serpentine zone, based on
mineralogy and geochemistry. The occurrence of Ni as
adsorbed and exchangeable cations, in carbonates, in
amorphous iron oxides, within the structure of crystalline iron
oxides and hydroxides, and in residual silicate layers within
each of the zones was determined. Qualitative analysis of
nickel in iron oxides, serpentine and talc using electron-probe
microanalyzer supports the results of the extraction
experiment. In limonite zones, dominated by goethite and
other secondary iron oxides, > 90% of the total nickel reside in
the crystal structure of Fe oxides. In the iron oxide –
magnesium silicate transition horizon and in the nickelenriched saprolite zone, respectively, > 80% and an average of
77% of the nickel are distributed in Fe oxides and within the
octahedral layers of serpentine. The remaining Ni ions not
taken up by these crystalline minerals are mostly associated
with amorphous Fe oxides. An EPMA image, depicting
relative abundance of Ni, Mg, and Fe in a section of weathered
bedrock, implies that Ni is more closely associated with Fe
than with Mg. An industrially significant output of this
research is the finding that residual silicates, which take an
enormous amount of acid to dissolve, need not be dissolved in
order to optimize the beneficiation of nickel.
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614
Goldschmidt Conference Abstracts
Geochemistry of eastern North
American CAMP diabase dykes
Productivity and circulation changes
during the last deglaciation from
biomarkers and Nd isotopes
S. CALLEGARO1*, A. MARZOLI1, H. BERTRAND2,
L. REISBERG3, M. CHIARADIA4 AND G. BELLIENI1
University of Padua, Department of Geosciences, Italy
(*correspondence: [email protected],
[email protected], [email protected])
2
Laboratoire de Géologie de Lyon, UMR-CNRS 5570, Lyon,
([email protected])
3
CRPG (CNRS UPR2300), Université de Lorraine, France
([email protected])
4
Université de Genève, Switzerland
([email protected]).
1
Swarms of diabase dykes and a few sills of the Central
Atlantic magmatic province (CAMP) intruded the Piedmont
area of the Appalachians and the coastal plains of eastern
North America (ENA) between 202 and 195 Ma [1]. Based on
field observations, an age progression can be defined from
NW- to N- and NE-oriented dykes. The basaltic dykes are Mg,
Cr-, and Ni-rich, which may only in part reflect accumulation
of mafic minerals. Incompatible trace element contents are
fairly homogeneous and generally low, e.g. LaCh/YbCh (0.542.39), typical of melts issued from a quite depleted shallow
mantle-source. The incompatible trace element contents are
not correlated with isotopic compositions of ENA dykes,
which display a considerable spread in initial isotopic
signatures, i.e. 87Sr/86Sr200Ma (0.7043-0.7088), !Nd200Ma (-6.8+2.1) and 206Pb/204Pb200Ma (17.41–18.61). Pb isotopic
compositions plot above the NHRL, at positive "7/4 (10-17)
and "8/4 (19-73). Generally low 188Os/187Os200Ma ratios (0.127–
0.144), which argue for negligible amounts of crustal
contamination, coupled with the large range of Sr-Nd-Pb
isotopic compositions, suggest generation from a strongly
heterogeneous mantle source, probably metasomatized
lithosphere. The alternative, a deep enriched mantle source, is
unlikely because the crystallization temperatures calculated
[2] for high-Fo (up to Fo89) olivines (ca. 1350 °C) are not
supportive of a very hot (i.e. mantle-plume) origin (see also
[3]). Considering the isotopic compositions of ENA lava
flows, some dykes may have fed eruptions chemically similar
to the Newark Preakness and Hook Mt. flows, i.e. the
youngest flows from the Newark Supergroup basins, whereas
none of the analyzed basaltic dykes yields geochemical
compositions similar to the slightly older Orange Mt. basaltic
flows.
[1] Nomade S. et al. (2006) Paleo3 244, 326-344. [2] Putirka
K. (2008) Rev. Mineral. 69, 61-120. [3] Herzberg C. (2009),
Nature, 458, 619-623.
Mineralogical Magazine
E. CALVO1*, L.D. PENA2, C. PELEJERO3 AND I. CACHO4
Institut de Ciències del Mar, CSIC, Pg. Marítim de la
Barceloneta 37-49, Barcelona, Spain
(*correspondence: [email protected])
2
Lamont-Doherty Earth Observatory of Columbia University,
61 Route 9W, Palisades, NY 10964, USA
3
ICREA and Institut de Ciències del Mar, CSIC, Pg. Marítim
de la Barceloneta 37-49, Barcelona, Spain
4
GRC Geociències Marines, Dept. d’Estratig., Paleontol. i
Geociències Marines, Universitat de Barcelona, Spain
1
The Eastern Equatorial Pacific (EEP) is thought to have
exerted a strong control over glacial/interglacial CO2
variations through its link to circulation and nutrient-related
changes in the Southern Ocean. Changes in phytoplankton
productivity and composition associated with increases in
equatorial upwelling intensity and influence of Si-rich waters
of Sub-Antarctic origin have been recently detected in ODP
Site 1240 (0º 01.31’N, 86º 27.76’W; 2,921 mbsl) [1].
However, these changes do not seem to have been crucial in
controlling atmospheric CO2, as they took place during the
deglaciation, when atmospheric CO2 concentrations had
already started to rise. New results from Nd isotopes in
foraminifera shells of Neogloboquadrina dutertrei from the
same intervals corroborate this interpretation. N. dutertrei
preferentially dwells in the lower thermocline, at the core of
the Equatorial Undercurrent (EUC). Therefore, changes in the
Nd-isotopic composition of these foraminifera will reflect the
composition of the EUC, which, in turn, reflects changes in
the advection of Sub-Antarctic Mode Water and Antarctic
Intermediate Water and the composition of the Southern
Ocean end-member. Our evidence indicates that diatoms
outcompeted coccolithophores at times when the influence of
Si-rich Southern Ocean intermediate waters was greatest as
recorded by low #Nd values (-2.8). This shift from calcareous to
non-calcareous phytoplankton would cause a lowering in
atmospheric CO2 through a reduced carbonate pump, as
hypothesized by the Silicic Acid Leakage Hypothesis.
However, the concomitant intensification of Antarctic
upwelling brought large quantities of deep CO2-rich waters to
the ocean surface. This process very likely dominated any
biologically mediated CO2 sequestration, and probably
accounts for most of the deglacial rise in atmospheric CO2.
[1] Calvo, E., et al. (2011), Proceedings of the National
Academy of Sciences 108 (14), 5537-5541.
www.minersoc.org
Goldschmidt Conference Abstracts
Nickel isotopes, BIFs and the
Archean oceans
V. CAMERON1*, D. VANCE1 AND S. POULTON2
BIG, Dept. of Earth Sciences, University of Bristol, Bristol
BS8 1RJ, UK (*correspondence: [email protected])
2
School of Civil Engineering & Geosciences, Newcastle
University, Newcastle upon Tyne NE1 7RU, UK
The weathering of platinum from
nuggets and platinum immobilisation
by Cupriavidus metallidurans
G. CAMPBELL1, F. REITH2, L. MACLEAN3 AND
G. SOUTHAM1*
1
Trace metal isotopes provide vital clues to the Earth’s
biogeochemical evolution. Key to these efforts is the
development and application of new isotopic systems of
bioessential elements important to specific organisms or
metabolisms or, as recorders of changing environmental
conditions through time. Nickel (Ni) is primarily restricted to
microorganisms and metabolisms that might have evolved in a
much different Archean environment [1-3]. Methanogens and
their particular metabolism, methanogenesis, purportedly fit
the criteria for an ancient origin of evolution and many studies
have shown the absolute requirement that these
microorganisms have for Ni.
Recently, we published the first measurements of nickel
stable isotopes from abiotic terrestrial materials and pure
cultures of methanogens [4]. Terrestrial samples representing
the mantle and crust displayed very little isotopic variability
(average #60Ni of 0.15 ± 0.24‰, 2$). In contrast, Ni isotopes
were significantly fractionated by pure cultures of
methanogens. The largest fractionation, #60Ni of -1.46 ±
0.08‰, was achieved by a methanogenic hyperthermophile.
Our data suggest the biological cycling of Ni may be an
important contributor of Ni isotopic variations in the rock
record. Furthermore, biological fractionation of Ni has the
potential to be a powerful new biomarker particularly in
regards to the nature and impact of early life.
We have started evaluating our new Ni isotopic tool by
applying it to the measurement of Ni stable isotopes in banded
iron formations (BIFs). In order to characterize the Ni isotopic
composition of the geochemical and biological environment of
the primitive Earth, it is essential to first understand the state
and changing conditions of the Archean oceans. Such
information recorded within BIFs and other terrestrial
materials is necessary to support our continued efforts to
establish Ni stable isotopes as a functional and detectable
biosignature.
[1] Bapteste et al. (2005) Archaea 1, 353-363. [2] Fraústo da
Silva & Williams (2001) in The Biological Chemistry of the
Elements: The Inorganic Chemistry of Life (Oxford University
Press, Oxford), pp. 436-449. [3] Tice & Lowe (2006) Earth
Sci Rev 76, 259-300. [4] Cameron et al. (2009) Proc Natl
Acad Sci USA 106, 10944-10948.
Mineralogical Magazine
615
Department of Earth Sciences, The University of Western
Ontario, London, ON Canada N6A 5B7 (*correspondence:
[email protected])
2
School of Earth and Environmental Sciences, The University
of Adelaide, CSIRO Land and Water, Waite Laboratories,
Urrbrae, South Australia, Australia
3
Canadian Light Source Inc.$, 101 Perimeter Road, $Saskatoon,
SK $Canada S7N 0X4
1
Platinum nuggets, collected from a platiniferous and
auriferous site near Fifield, New South Wales, Australia were
examined to evaluate mineral dissolution-precipitation
processes occurring at the nugget–‘soil solution’ interface.
Nuggets possessed striations indicating mechanical transport
with the soil environment and micrometer-scale dissolution
pits corresponding to regions possessing soil materials (quartz,
clays and organics) and acicular, iron oxides suggesting an
oxidising weathering environment. The occurrence of 100 nmscale, cubic minerals at the soil solution interface and
comparably sized cubic dissolution ‘pits’ suggest that
platinum weathering occurs via preferential dissolution of the
‘bulk’ platinum nugget (an Fe-Pt alloy). Examination of these
cubic minerals using scanning electron microscopy in
secondary electron and back-scattered electron (BSE) imaging
modes, and using energy dispersive spectroscopy indicated
that they are enriched with copper (i.e., a Cu-Pt alloy).
Growth of platinum nuggets via secondary platinum mineral
formation was not observed. Cupriavidus metallidurans
cultures reacted with 0.5 and 5 mM platinum (IV) chloride,
immobilised platinum from solution rapidly i.e., within
minutes. EXAFS/XANES analysis of these reaction systems
demonstrated that most of the Pt(IV) chloride complex was
reduced to Pt(II) and that platinum binding shifted from
chloride to primarily, amino functional groups. Using
transmission electron microscopy, C. metallidurans was also
found to precipitate nm-scale colloidal platinum when exposed
to 5 mM platinum (IV) chloride; the formation of these
colloids occurred within the bacterial cell envelope.
Understanding the biogeochemistry of platinum, in particular
weathering and formation of colloids has important
implications within geologic settings, i.e., for platinum
dispersal in relation to exploration geochemistry programs.
www.minersoc.org
616
Goldschmidt Conference Abstracts
Kinetic modeling of microbial Fe(II)
oxidation, Fe(III) hydrolysis, and
mineral precipitation in acid waters
K.M. CAMPBELL* AND D.K. NORDSTROM
U.S. Geological Survey, Boulder, Colorado, 80303, USA
(*correspondence: [email protected])
Acidophilic
Fe(II)-oxidizing
microorganisms
are
widespread in acidic mine-impacted waters and are the
primary drivers for Fe(II) oxidation at low pH. The resulting
changes in Fe chemistry have profound effects on trace
element redox cycling and mobility in the environment.
Sorption, precipitation, or redox activity of Fe(III)-containing
mineral phases control the mobilization or sequestration of
metal(loids) of concern in natural waters. Although Fe(II)
oxidation is microbially-mediated, biogeochemical predictions
for an acidic, Fe(II)-rich natural water require a coupled
biotic-abiotic process model.
We present experimental and model results from a series
of batch experiments conducted at four initial Fe(II)
concentrations (10, 50, 100, and 159 mM), three initial pH
values (2.0, 2.5, and 3.0), and inoculated with a pure strain of
Acidithiobacillus ferroxidans isolated from acid rock drainage
near a molybdenum mine. The pH, aqueous Fe(III), Fe(II),
direct cell counts, and solid phase precipitates were monitored
over the course of the experiments. For all inital Fe(II)
concentrations except 10 mM, the pH increased initially, due
to the acid-consuming stoichiometry of Fe(II) oxidation, but
then decreased due to the combined effects of Fe(III)
hydrolysis
and
precipitation
of
schwertmanite
(Fe8O8(OH)6SO4) and/or jarosite (KFe3(SO4)2(OH)6). The
Fe(III) concentration in the 10 mM Fe experiments was too
low to precipitate jarosite, and only an increase in pH from
Fe(II) oxidation was observed. The amount of pH increase
due to Fe(II) oxidation was greatest at an initial pH of 2 for all
initial Fe concentrations. The final pH in all bottles at 50 mM,
100 mM, and 159 mM Fe was very similar (pH 2), regardless
of inital pH, because of equliibrium with mineral precipitates,
primarily jarosite. Since the decrease in pH was due to both
hydrolysis and precipitation, the kinetics of Fe(III) hydrolysis
were measured in a separate experiment. PHREEQC, a
geochemical model with the ability to incorporate multiple
kinetic expressions, was used to simulate the experimental
results by including kinetic expressions for microbial Fe(II)
oxidation, Fe(III) hydrolysis, and jarosite precipitation. In
addition, we compared various proposed kinetic formulations
for microbial Fe(II) oxidation from the literature to our
experimental results.
Mineralogical Magazine
C, Sr isotopes in cap carbonate and
and Ce anomaly in BIFs of Jucurutu
Formation, Seridó Belt, NE, Brazil
M.S. CAMPOS1, A.N. SIAL1*, C. GAUCHER2,
V.P. FERREIRA1, ROBERT FREI3, R.C. NASCIMENTO4 AND
M.M. PIMENTEL5
NEG-LABISE, Dept. Geol. UFPE, Recife, 50670-000, Brazil
(*correspondence: [email protected])
2
Facultad de Ciencias, Universidad. de la Republica,
Montevideo,Uruguay ([email protected])
3
Univ. Fundação do Amazonas, Manaus, Brazil
4
Inst. Geography and Geol., Univ. Copenhagen, Denmark
5
Inst. Geoc., Univ. Fed. Rio G. do Sul, Porto Alegre, Brazil
1
BIFs associated with Neoproterozoic glaciations are an
important pillar of the Snowball Earth hypothesis and are
regarded as accumulation of Fe+2 in ice-capped anoxic ocean.
BIFs at Jucurutu (Mina do Bonito), Florânea (Cabeço da
Mina) and São Mamede (Riacho Fundo) towns, Seridó Belt
(itabirite and Fe ores, amphibole-itabirite, and tremolite schist)
are overlain by Jucurutu marbles. Micro-drilled carbonate
samples from the Jucurutu Formation exhibit #13C values as
low as -12‰ in the first meter, followed by mantle values (-6
to -4‰) and then by positive values up section (+4 to +10‰).
Surprisingly, #13C values for carbonates that overlie itabirites
at Riacho Fundo and at Cabeço da Mina are all positive.
Perhaps, the difference of C isotope behavior between basal
carbonates at Mina do Bonito (negative), and Riacho Fundo
and Cabeço da Mina (positive) reflect, perhaps, topographic
control during deposition.
C-isotope stratigraphy for carbonates of the Jucurutu
Formation support their deposition as cap carbonate. Negative
#13C values are followed upsection by positive values. Sr
isotope ratio for Jucurutu carbonates (~0.7074) approach Sr
isotope ratios for Sturtian II cap carbonates (e.g. Maiberg,
Pedro Leopoldo, Mirassol D´Oeste among others) between
740 and 635 Ma.
Negative Ce anomaly values (<0.10) result from Ce
depletion or fractionation with metallic oxides, therefore, it
indicates oxidizing conditions of the ocean water [1]. On the
other hand, positive values (>0.10) reflect anoxic conditions of
the ocean water. The values of Ce/Ce* in the BIFs vary from
0.54 to 2.46, indicating extremely anoxic environment, which
seems to support the hypothesis of deposition of BIFs in an
ocean capped by ice.
[1] Kato et al. (1996). Journal Southeast Asian Earth Sci. 14
161–164.
www.minersoc.org
Goldschmidt Conference Abstracts
Kaolinite as a sorbent for As natural
contamination
B. CAMPREDON, C. HUREL AND N. MARMIER
Changes in organic aerosol
composition with aging inferred from
aerosol mass spectra
M.R. CANAGARATNA1,*, N.L. NG1, J.L. JIMENEZ2,
P.S. CHHABRA3, J.H. SEINFELD3 AND D.R. WORSNOP1
LRSAE – Sci. Fac., University of Nice Sophia Antipolis, Parc
Valrose, 28 avenue Valrose, 06108 Nice cedex 2 France
The geological formation of the Mercantour basin is made
of metamorphic rocks, granite, Permian argillite and
sedimentary rocks, which can provide high arsenic
concentrations in the riverine waters. In the Var (South of
France) watershead high arsenic input were measured, and
were attributed to the dissolution of the metamorphic rocks
form the old massifs of Mercantour. This natural
contamination may affect the geological environments, since
the sediments are the main sinks of pollutants. When the
environmental conditions are changed (hydrologic conditions,
flow variation, pH, redox potential, etc.) the sediments can act
as a source of contamination. In this study, kaolinite (a clayey
material) was chosen as a potential binding agent for trapping
the local excess of As. This adsorbent material was chosen on
the basis of his natural occurrence in the studied watershead
ecosystem.
Figure 1: As adsorption on Kaolinite in NaNO3 0.1M and
13.3µM initial As concentration.
Adsorption of As on kaolinite was studied in various
electrolytic conditions (concentration and composition),
various solid to liquid ratios and various pH conditions (figure
1). The results were modeled considering empirical models
and mechanistic models (surface complexation).
Mineralogical Magazine
617
Aerodyne Research, Inc, Billerica, MA, USA
(*correspondence: [email protected],
[email protected], [email protected])
2
CIRES & Department of Chemistry and Biochemistry,
University of Colorado, Boulder, CO, USA
([email protected])
3
Department of Chemical Engineering, California, Institute of
Technology, Pasadena, CA, USA, ([email protected],
[email protected])
1
The Aerosol Mass Spectrometer (AMS) provides real-time
quantitative mass concentrations of non-refractory species in
ambient aerosols. Factor analysis of ambient AMS organic
aerosols (OA) spectra has been used to characterize the
evolution of OA composition due to photochemical
processing. A large database of ambient OA components has
been analyzed with the “triangle” plot [1], in which f44, ratio of
m/z 44 (mostly CO2+ from acid-derived groups) to total signal
in the component mass spectrum, is plotted against f43 (mostly
C2H3O+ from non-acid oxygenates). Examination of ambient
oxidized organic aerosol (OOA) components in the triangle
plot indicates that the relative acid group content and
similarity of OA components increase with aging. A new
parameterization of the H:C of OA components in term of f43
allows for further transformation of this data into the Van
Krevelen diagram (H:C vs. O:C) [2]. Ambient OOA
components also map out a triangular space in Van Krevelen
diagram, showing a range of H:C at lower oxidization which
decreases with increasing oxidation. The average slope
("H:C/ "O:C) that describes the transformation between the
less and more aged OOA components is ~-0.5. This slope is
consistent with the additions of both acid and alcohol
functional groups without fragmentation, and/or the addition
of acid groups with C-C bond breakage. The importance of
acid formation in OOA evolution is consistent with increasing
f44 in the triangle plot with photochemical age. The simple
triangle and Van Krevelen plots for laboratory SOA formed in
chamber experiments are also investigated.
[1] Ng, N. L., et al. (2010) Atmos. Chem. Phys., 10, 46254641. [2] Heald, C. L., et al. (2010), Geophys. Res. Lett., 37,
L08803.
www.minersoc.org
Goldschmidt Conference Abstracts
618
The many flavors of oxygenminimum zones past and present
DONALD E. CANFIELD
NordCEE and Institute of Biology, University of Southern
Denmark, University of Southern Denmark, Campus vej
55, 5230 Odense M, Denmark
Oxygen-deficient oxygen minimum zones (OMZs) are
concentrated today in only a few regions of the global ocean.
They are truly anoxic and despite their limited areal extent,
they are sites of globally-significant rates of nitrogen loss as
N2 gas. While this loss was traditionally ascribed to canonical
heterotrophic denitrification, recent work has demonstrated
that most nitrogen loss is, instead, channeled through the
anammox (anaerobic ammonia oxidation) process. Active
nitrogen cycling was thought to inhibit sulfate reduction,
explaining the lack of sulfide into these oxygen-free waters.
New results show, by contrast, that these waters likely support
an active, but cryptic, sulfur cycle, where sulfide produced by
sulfate reduction is actively oxidized through nitrate reduction.
Metagenomic results confirm the presence of microbial sulfurcycling communities, and through their activities, these
organisms may contribute to significant amounts of organic
matter mineralization in OMZ water and to the ammonia
driving anammox. Accumulating evidence suggests that in the
past, oxygen minimum zones supported chemistry quite
different from those found today. Many instances of both
sulfidic and ferrugenous OMZs, extending well into the
Precambrian, have now been described. We are still
challenged to understand the circumstances responsible for the
development of these different styles of OMZ water
chemistry. However, the different flavors of OMZs through
time must reflect the evolving chemistry of the coupled oceanatmosphere system through time, and how this has controlled
the variable expression of the different microbial populations
known to inhabit OMZs today.
The alteration and the
fluid inclusion characteristics of the
Çavdır (Burdur) copper
mineralization, SW Turkey
Z. CANSU1* AND H. EMRE1
Istanbul University, Department of Geological Engineering,
34230, Istanbul, Turkey
(*correspondence: [email protected])
Çavdır (Burdur) copper mineralization, located in
southwestern Turkey, occurs in the gabbros of the Lycian
Allochthon. The mining district has a few meter wide vein
systems that contain malachite±azurite, plus minor
chalcopyrite, bornite, iron minerals such as goethite, hematite
and magnetite in quartz gangue. The strike of major orebearing veins is N 30o to 45o E that are nearly paralel to the
major fault in the study area. The veins are accompanied by
extensive alteration.
Qualitative clay analysis were made to define alteration
minerals and kaolinite, smectite, illite, zeolite, chlorite group
minerals, cristobalite were determined by X-Ray
Diffractometer method.
Microthermometric measurements were done on fluid
inclusions of the quartz gangue. Fluid inclusions are two
phased L+V (liquid+vapour) and NaCl-H2O in system. Mean
homogenization temperature is measured as 283oC, the mean
salinity is calculated from the equation %NaCl= [(-1,78x
Tmice)-(0,0442xTmice2)-(0,000557xTmice3)] [1] as %8 NaCl
equivalent and the mean density is found as 0,82 gr/cm3 by
plotting % NaCl equivalent versus Th (oC) [2].
These alteration and microthermometric datas connote an
epithermal system. In the light of the acquired datas, it is
suggested that the mineralization occurred in the effect of
tectonic control and the heated ground water by the crust
tickening (because of the emplacement of the Lycian thrust
sheets) and geothermal gradient mobilized copper minerals
from parental rocks.
[1] Bodnar (1993) Geochemica et Cosmochimica Acta 57,
683-684. [2] Wilkinson (2001) Lithos 55, 229-272.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Zircon U-Pb chronology and
geochemistry of Late Paleozoic-Early
Mesozoic intrusive rocks in eastern
segment of the northern margin of
the North China Craton, NE China
and its tectonic implications
H.H. CAO, W.L. XU *, F.P. PEI AND F. WANG
College of Earth Sciences, Jilin University, Changchun
130061, China ([email protected];
(*correspondence: [email protected])
Chronological and geochemical data of Late PaleozoicEarly Mesozoic igneous rocks in the Kaiyuan-Panshi area, NE
China, provide insights for the Late Paleozoic-Early Mesozoic
tectonic evolution in the eastern segment of the northern
margin of the North China Craton (NCC). LA-ICP-MS zircon
U-Pb dating results indicate that the Late Paleozoic-Early
Mesozoic magmatisms can be subdivided into three stages,
i.e., the middle Permian (~270 Ma), the late Permian-early
Triassic (259~249 Ma), and the late Triassic (~222 Ma).
The middle Permian magmatisms consist chiefly of
garnet-bearing monzogranites. Their SiO2-high and Al-rich
geochemical feature suggest that they could have formed
under a setting of crustal thickening.
The late Permian-early Triassic intrusive rocks are
composed mainly of the gabbro, monzodiorite, monzonite,
monzogranite, and syenogranite. Chemically, they belong to a
calc-alkaline series and are characterized by enrichment in
LILEs and depletion in HFSEs and P. Combined with the
contemporaneous high-Mg andesites in the adjacent area, we
propose that they could have formed under an active
continental margin setting.
The late Triassic igneous rocks are composed of pyroxeneperidotites and olivine-pyroxenite with cumulate texture.
Combined with the existence of coeval A-type granites and
mafic-ultramafic rocks in the adjacent area, it is suggested that
they could form under an extensional environment.
Taken together, we propose that the collision and
subduction between the continent (NCC) and the island arc
could happen in eastern segment of northern margin of the
North China Craton from the middle Permian to early Triassic,
and that a post-orogenic extension environment occurred in
the study area in the late Trassic.
This research was financially supported by research grants
from the Natural Science Foundation of China (Grant
41072038) and the Geological Survey of China (Grants
1212010611806 and 1212010070301).
Mineralogical Magazine
619
Difference of organic matter in the
Early Cambrian Ni-Mo-bearing
black rock series in the Zunyi city of
South China: Implications for the
origin of the deposits
JIAN CAO*, CHUNHUA SHI, KAI HU, SHANCHU HAN,
LIZENG BIAN AND SUPING YAO
State Key Laboratory for Mineral Deposits Research (Nanjing
University); School of Earth Sciences and Engineering,
Nanjing University, Nanjing, 210093
(*correspondence: [email protected])
The Ni-Mo polymetallic mineral deposits in the Zunyi city
of South China is likely the most representative case of such
deposits worldwide, and thus have received large research
attentions during recent years. The issue is disputable as the
origin of the deposits has been reported to be of sea water or
hydrothermal sources. In this work, we mainly reported the
difference of organic matter between the metallic and nonmetallic intervals, and further addressed the origin of the
deposits.
Analytical results from petrography, organic and
elemental geochemistry showed that biogenic and organic
matters occur widely both in the metallic and in the nonmetallic intervals, indicating important effects on the
formation of the deposits. The matters vary in abundance, type
and maturation between the metallic and non-metallic
intervals. For example, the organic matter abundance and
maturity of the metallic interval are both the highest in the
section. In addition, a special organic matter in elliptical shape
was only observed in the metallic interval. The mineral
element may be sourced either from sea water or from
hydrothermal water. In particular, the sea water and
hydrothermal water may be the dominant source for Mo and
Ni, respectively. The mineralization of Mo and Ni is relatively
early and late, respectively. Based on these results, a new
mineralization model was tentatively established.
www.minersoc.org
620
Goldschmidt Conference Abstracts
Geochronology and geochemistry of
Xingdi No. 1 intrusion in Kuluketage,
NW China: Tectonic implication for
Xingdi mafic-ultramafic rock belt
XIAOFENG CAO1,2, XIANG GAO1, XINBIAO LÜ1,2*,
YUEGAO LIU1, SHENTAI LIU1 AND CHAO CHEN1
Faculty of Earth Resources, China University of Geosciences,
Wuhan 430074, China
(*correspondence:[email protected]; [email protected])
2
State Key Laboratory of Geological Processes and Mineral
Resources, China University of Geosciences, Wuhan
430074, China
1
The Xingdi No. 1 mafic-ultramfic intrusion is the largest
in the Xingdi mafic-ultramafic belt with an exposed area of ca.
20 km2 and intruded into the Paleoproterozoic basement.
Gabbro is the major rock type and there is minor olivine
pyroxenite. Sm-Nd geochronometry of the gabbro gives an
isochron age of 761.2±31.2 Ma. It is the same with the
intrusion age of Xingdi No. 2 pluton (760±6 Ma). The gabbro
is systematically enriched in large ion lithosphere elements
(LILE), light rare earth elements (LREE) and depleted in high
field strength elements (HFSE) and heavy rare earth elements
(HREE). The studied rocks are characterized by low wholerock and mineral #Nd(t) values (%7.8 to %7.1) and elevated
(87Sr/86Sr)i values (0.7066–0.7073). These geochemical
characteristics, together with the presence of the abundant
hornblende, biotite, bladed biotite enclosed in amphibole, and
crescent-shaped Paleoproterozoic wall-rock enclosed within
the intrusion are key features of magma mixing in the source
or assimilation during its emplacement. The rocks have Zr/Y
ratio of 3.81–13, which fall in the area of within-plate basalt
area. As the Xingdi No. 1 and No. 2 plutons formed at the
same period and display similar geochemical characteristics,
we propose that they formed within the same tectonic setting
and derived from the same origin, but No.1 experienced higher
extent of evolution and contamination. On the basis of
previous studies, the Neoproterozoic tectonic and magmatic
events in Kuluketage comprise syn-collisional granite around
TC (ca. 1.0–0.9 Ga), post-collisional K-rich granite and
alkaline mafic-ultramafic intrusions (ca. 830–800 Ma) and
rifting-related mafic-ultramafic plutons, dykes and bimodal
volcanic rocks (ca. 774–744 Ma).
This work is founded by 305 Project of State Science and
Technology Support Program (Grant No. 2007BAB25B04).
Mineralogical Magazine
CO2 sequestration in deep aquifers:
Insights into future hazards from a
natural analog (Campi Flegrei, Italy)
R. CAPOBIANCO1*, R. ESPOSITO1, R.J. BODNAR1,
G. CHIODINI2 AND J.D. RIMSTIDT1
Virginia Tech, Blacksburg, VA 24061, USA
(*correspondence: [email protected])
2
Istituto Nazionale di Geofisica e Vulcanologia, sezione di
Napoli, Osservatoria Vesuviano, 80124 Napoli, Itally
1
Among the major challenges facing the world today are
climate changes and the alteration of Earth’s surface
geochemistry that are occurring as the result of release of
anthropogenic CO2 into the environment. Geologic
sequestration of CO2 in deep aquifers is an approach to
reducing CO2 emissions to the atmosphere that has recieved
much attention recently [1]. The largest of the sequestration
projects currently underway, the In Salah Project (Algeria)
injects approximately 1 Mt of CO2 per year [2]. A large coalfired powerplant emits over an order of magnitude more CO2
than this; for example, the Scherer plant (GA, US) emitted
about 25 Mt in 2010 [3].
Campi Flegrei is a natural analog for large-scale CO2
sequestration in confined saline aquifers. At Campi Flegrei
active magmatism at depth is releasing large amounts of CO2
that migrate upward into a confined saline aquifer at depths of
about 2-3 km. Campi Flegrei is estimated to have injected 63
Mt of H2O and CO2 during the crisis of 1982-1984,
corresponding to a total volume increase of 5.7*107 m3 or
2.85*107 m3/y [4]. This is similar to the volume (2.4*107 m3)
that would be occupied by the annual CO2 emissions from the
Scherer plant at the T&P conditions of interest in a geologic
sequestration scenario. We predict that large-scale
sequestration of CO2 as a supercitical phase will have
consequences similar to those observed at Campi Flegrei –
seismic activity, bradyseism, and release of CO2 rich fluids
from the aquifer to the surface. These effects may be mitigated
to some extent through careful management of the reservoir
during and following injection.
[1] Benson & Cole (2008) Elements 4(5), 325-331. [2] Michel
et al. (2010) International Journal of Greenhouse Gas Control
4(4), 659-667. [3] Environmental Protection Agency (2011),
2010 Coal Unit Characteristics. [4] Lima et al. (2009).
[4] Earth-Science Review 97(1-4), 44-58.
www.minersoc.org
Goldschmidt Conference Abstracts
VSI study of biotite dissolution at
acidic pH and 25-50˚C
C. CAPPELLI1*, J. CAMA2, F.J. HUERTAS 1
Instituto Andaluz de Ciencias de la Tierra (IACT), CSICUGR, Avenida Fuentenueva s/n., 18002 Granada, Spain
(*correspondence: [email protected])
2
Institute of Environmental Assessment and Water Research
(IDAEA), CSIC, Jordi Girona 18-26, 08034 Barcelona,
Catalonia, Spain
1
Generally, the dissolution rates of the phyllosilicates that
comprise the mica group (e.g. muscovite, biotite and
flogopite) were obtained from experiments in which ground
powders were used, and the calculated rates were normalised
either to total or edge surface area, derived from BET
measurements. Using the vertical scanning interferometry
(VSI) technique we attempt to compute biotite dissolution
rates from quantifying surface normal retreat of the cleavage
(001) surface at pH 1 and 25, 40 and 50 ºC. The advantage of
these measurements is that allows us to obtain biotite
dissolution rates from mineral surface retreat, and thus
avoiding the need to normalize the dissolution rates with
externally measured surface areas.
Single biotite fragments of approximately 100 mm2 were
placed in 250 mL of 0.1 M HNO3 solution (pH 1) and 25, 40
and 50 ºC for almost two weeks. During this time span the
cleavage surface was examined by VSI after 4, 7 and 13 days.
On the one hand, dissolution features were observed on the
cleavage surface, and on the other hand, the dissolution rates
were computed from surface retreat compared to a non-reacted
reference surface.
The calculated biotite dissolution rates, with an average
error of ~10 %, were 2.5 x 10-8, 1.1 x 10-8 and 0.3 x 10-8 mol
m-2 s-1 at 50, 40 and 25 ºC, respectively, which are higher than
those calculated from the total mineral surface area, although
rates normalized to total surface area may have little relevance
for micas, since reactive sites probably are concentrated on
edge surface [1]. VSI examinations of the reacted cleavage
surface show that biotite dissolution was controlled by
preferential surface edge dissolution.
The calculated activation energy of the biotite dissolution
at pH 1 from the rates obtained at 25, 40 and 50 ºC is 14.35
kcal mol-1 (R2 = 0.997), which is similar to that of biotite
dissolution at very acidic pH [2].
621
Spin transition in Fe-bearing
perovskite: Implications for the
lower mantle
RAZVAN CARACAS
CNRS, ENS Lyon, UMR5276, Lyon, Frence
Using lattice dynamical calculations based on density
functional perturbation theory we are able to disentangle a part
of the complex phase diagram and spin behavior of the
(Mg,Fe)SiO3 perovskite (pv). To do this we investigate the
dynamic stability of Pbnm FeSiO3 pv and show the existence
of unstable phonon modes. We track the eigen-displacements
of the phonons modes to find low-spin and intermediate spin
states. On solid-state physical basis we explore a set of
hypothetical structures with various spin configurations and
considerably lower enthalpy than the parent orthorhombic
Pbnm structure. We show that the spin evolves along a highspin to mixed high- and intermediate spin to low-spin
transition sequence. We also analyze the thermal behavior of
both high-spin and low-spin phases and we discuss a first
thermal phase diagram.
We show that the elastic moduli and the bulk seismic
wave velocities are weakly affected by the spin transition.
However, the intrinsic differences in seismic anisotropy
between the high-spin and low-spin phases of Fe-bearing pv
coupled with lattice preferred orientation that can develop
during mantle flow lead to distinct seismic signatures between
the top and the bottom of the lower mantle [1]. These
signatures are detectable by seismic observations and they
need to be taken into account in tomographic studies of the
Earth's lower mantle.
Finally, we find that the electronic gap widens during
crossover to the low-spin phase. This has a direct influence on
the electircal conductivity and agrees qualitatively with in situ
measurements [2].
[1] Caracas, Mainprice, and Thomas (2010) Geophys. Res.
Lett. 37, L13309. [2] K. Ohta, et al. (2008) Science 320, 89.
[1] Kalinowski & Schweda (1996) GCA 60, 367-385 [2]
McMaster et al. (2008) MinMag 72, 115-120
Mineralogical Magazine
www.minersoc.org
622
Goldschmidt Conference Abstracts
Fe-rich stalactites from Libiola mine:
Mineralogical and geochemical
features
C. CARBONE1*, E. DINELLI2, P. MARESCOTTI1 AND
G. LUCCHETTI1
1998-2010 more than ten years of soil
CO2 flux measurement at Solfatara of
Pozzuoli (Campi Flegrei, Italy)
C. CARDELLINI1*, G. CHIODINI 2, S. CALIRO 2,
D. GRANIERI3, R. AVINO2, F. FRONDINI1.
1
DIP.TE.RIS, University of Genova, Corso Europa, 26, Italy
(*corrrespondence: [email protected])
2
Dip. di Scienze della Terra e Geologico-Ambientali, Alma
Mater Studiorum - Università di Bologna, Italy
1
Università di Perugia, Perugia, Italy
(*correspondece: [email protected])
2
INGV sez. Napoli, Napoli, Italy
3
INGV sez. Pisa, Pisa, Italy
The aim of this work is to characterize the mineralogy of
different-shaped Fe-rich stalactites as well as to investigate the
physico-chemical parameters of the associated mine and drip
waters. The mineralogy has been investigated by means of
reflected and transmitted light microscopy, XRPD, SEM-EDS,
EPMA-WDS, and TEM-EDS analyses. Mine and drip waters
have been sampled for chemical analyses. Water temperature,
electrical conductivity, alkalinity by acidimetric titration, pH,
and Eh were determined in the field during sampling. In the
laboratory, waters have been analyzed for: Mg, and Ca by
AAS, Na and K by AES Cl, SO42-, and NO3- by ionchromatography, Si, Fe, minor and trace elements by ICPOES. Three different types of stalactites were distinguished on
the basis of their morphology: 1) “soda straw”-,
2) “deflected”-, and 3) “coned shaped”-stalactites.
Mineralogical results showed that all the samples are
characterized by poorly crystalline Fe-rich phases associated
to goethite with different degree of crystallinity. Nevertheless,
there are significant differences either in their texture and
chemistry. The “soda straw” stalactites are enriched in Cu and
Zn and evidenced botroydal to mammellonar textures; the
“deflected” stalactites are enriched in Ni and showed
concentric layering characterized by sheaves of radiating
fibers; the “coned shaped” stalactites are enriched in Cu, Zn
and Ni and evidenced a concentric layering maked by the
alternance of botroydal/mammellonar and fibrous-radiating
textures. Geochemical investigations evidenced that the
composition and physico-chemical parameters of mine and
drip waters are in any case different from the other AMD
occurrences in the mining area [1, 2]. All water samples
contain Cu, Ni, and Zn to appreciable levels, and the physicochemical conditions are consistent with stability of
ferrihydrite, which however tends to transform to goethite
upon ageing. Few of the mine waters plot close to the
metastability field of schwertmannite.
With a flux of deeply derived fluids of ~5000 t/d and an
energetic release of ~100 MW Solfatara of Pozzuoli is one of
the largest studied volcanic-hydrothermal system of the world.
Since 1998, CO2 flux surveys where performed using the
accumulation chamber method: i) over a large area, including
the volcanic apparatus and its surroundings, ii) at fixed points
inside the crater and ii) by two automatic stations. The
monitoring of CO2 fluxes allowed to recognize both “longterm” and “short-term” variations in the degassing of the
Solfatara system. The main “long-term” CO2 flux variation
consisted in the expansion of the area interested by anomalous
soil CO2 degassing which doubled since 2003. This variation
mainly occurred external to the Solfatara cone in
correspondence of a major fault system NE-SW oriented and
was correlated with the occurrence in 2000 of relatively deep,
LP seismic events, which were interpreted as the indicator of
the opening of an easy-ascent pathway for the transfer of
magmatic fluids towards the shallower domain hosting the
hydrothermal system. The input of these magmatic fluids has
been highlighted by the changes in the chemical and isotopic
compositions of fumarolic fluids. “Short-term” variations of
CO2 flux were recorded by both automatic stations and at
fixed measurement points. A marked peak of the mean CO2
fluxes of fix points inside the crater occurred in 2000,
probably connected with the 2000 seismic crises. In 2006 an
evident anomaly was registered outside the crater. This
anomaly was interpreted as due to shallow permeability
changes along the NW–SE fault, induced by an earthquake
swarm of October 2006. The physical feasibility of the
interpretations of these variations was assessed by physicalnumerical simulations of the gas along a “faulted”
hydrothermal system. The relevant changes observed at Campi
Flegrei since 2000 have to be taken in to consideration for the
interpretation of the behaviour of this dangerous volcano.
[1] Dinelli & Tateo F (2002) Appl. Geochem, 17, 1081–1092.
[2] Marini et al. (2003) Geochem J. 37, 199–216.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Tectonic controls for high magmatic
fluxes within continental arcs:
The Jurassic and Paleogene
magmatic record of the Sierra
Nevada de Santa Marta, northern
Colombia
A. CARDONA1,2, V. VALENCIA3, G. BAYONA2,
C. MONTES1,2, M. DUCEA4, J.F. DUQUE5
3
AND J. VERVOORT
1
Smithsonian Tropical Research Institute, Panamá, Panamá.
(*correspondence: [email protected])
2
Corporación Geológica Ares, Bogotá, Colombia.
3
School of Earth & Environmental Sciences, Washington State
University, Pullman, USA.
4
Department of Geosciences, University of Arizona, Tucson,
USA.
5
Centro de Geociéncias, Universidad Autónoma de México,
Queretaro, México.
Magmatic fluxes in continental arcs have shown to include
major flare-ups episodes during their evolution. These
episodes reflect catastrophic events which may be connected
to major plate tectonic reorganizations. U-Pb zircon
crystallization from plutonic rocks (30 U-Pb LA-ICP-MS) and
detrital zircons (ca. 2000 U-Pb LA-ICP-MS detrital zircon
analysis) from northern Colombia have revealed the existence
of two major continental magmatic flare ups in the Middle
Jurassic (ca. 190-180 Ma) and the Paleogene (60-45 Ma).
Their tectonostratigraphic relations suggest that these two
episodes are related to different periods of subduction initation
along the Pacific margin of South America. The older is
related to an extensional type subduction formed after the
break-up of Pangea, whereas the younger Paleogene reflect
subduction initiation after arc- continent collision in the Late
Cretaceous. These tectonic correlations suggests that the early
episodes of subduction in continental margins are responsible
for the compositional modification of significant segments of
the continental crust.
Pre-eruptive history and longevity of
felsic magma in Iceland illuminated
by in situ U-Th dating and
trace-element analysis of zircon from
historical eruptions
T.L. CARLEY1*, C.F. MILLER1 AND J.L. WOODEN2
Vanderbilt U., Dept. of Earth and Environmental Sciences,
Nashville, TN, USA
(*correspondence: [email protected],
[email protected])
2
Stanford U. USGS-SUMAC SHRIMP Lab, Stanford, CA,
USA ([email protected])
1
We are investigating zircons from silicic volcanic rocks
from recent (primarily historical) eruptions in different
tectonic regions of Iceland: Torfajokull ~7500 and ~3100 BP
and 871 and 1477 AD (rift-tip); Hekla 1104 AD (transitional
to rift); and Oraefajokull 1362 AD (off-rift).
Precise
knowledge of these eruption ages, combined with relatively
high precision U-Th disequilibrium ages of zircon (in situ
SHRIMP-RG) that date crystal growth, permit us to elucidate
longevity of and processes within these felsic magma systems.
While zircon age distributions from individual eruptions are
variable, all display evidence for extensive growth that
predates eruptions by >10 k.y. Seventy percent of Hekla and
Torfajokull ages are older than 10 ka, with 60% of model ages
falling at 10-30 ka and reaching a maximum of 50 ka. The
predominance of older ages, the general paucity of <10 ka
ages, and observation of near-eruption age crystallization of
major phases (e.g., Torfajokull [1]) suggests that these zircons
experienced a history separate from that of magma in which
they erupted. Zircon morphology (presence of rounded
centers and grain boundaries), compositional zoning (core-torim complexities in Ti, Hf concentrations) and U-Th ages
together point to growth at relatively low temperatures,
subsequent storage in a subvolcanic, silicic mush or recently
solidified rock, and entrainment by the hotter erupting magma.
While Oraefajokull zircons are dominantly <10 ka, grain
morphology and trace-element zoning suggest a similarly
complex history. The erupted materials were likely ascending
magmas that entrained a pre-existing zircon cargo.
[1] Zellmer et al. (2008) EPSL 269, 387-397
Mineralogical Magazine
623
www.minersoc.org
Goldschmidt Conference Abstracts
624
Alkalic magmas and the diversity of
mantle compositional variation
Implications of a non-chondritic
primitive mantle for chemical
geodynamics
RICHARD W. CARLSON
Department of Terrestrial Magnetism, Carnegie Institution of
Washington, 5241 Broad Branch Road, NW, Washington,
DC 20015 USA, ([email protected])
As very small degree melts, mafic-alkalic magmas are
sensitive tracers of small-scale compositional heterogeneity in
the mantle. Some alkalic magmas contain trace element and
isotopic signatures indicative of sources dominated by
components derived from subducted sediments. Excellent
examples of this end member are the alkalic magmas of Italy.
In the north, mantle sources for these magmas contain tens of
percent subducted sediment whereas in the south, the sources
are just overprinted by small volume fluids released from the
subducting plate.
Many mafic-alkalic and carbonatitic
magmas, however, have isotopic compositions that overlap
values seen in intraplate oceanic basalts. Along with key OIBlike trace element ratios (e.g. Ce/Pb, Th/Ta) this suggests that
these magmas simply represent very low degree (<1%) melts
of “normal” mantle. Within this group, there are examples of
regional isotopic differences that suggest lithospheric sources.
For example, group I kimberlites from South Africa have !Nd
> +4 whereas similar composition kimberlites from Brazil
have !Nd < -4. The isotopic compositions of these kimberlite
groups, however, also overlap the range seen in slightly older
regionally-associated flood basalts, the Karoo and Parana,
respectively. This may suggest sources in lithospheric mantle
that was metasomatized by melts from compositionally
distinct sublithospheric mantle. Mafic-alkalic magmas from
Montana have OIB-like trace element characteristics, but
extreme isotopic compositions (e.g. !Nd often < -15)
indicating source metasomatism some 1.8 Ga prior to the
Cenozoic magmatism. Low 187Os/188Os in potassic ultramafic
magmas (kimberlites, katungites, meimechites) point to
peridotitic sources whereas more radiogenic Os in Na-rich
varieties (e.g. kamafugites, nephelinites) suggest pyroxenerich sources. Mafic-alkalic magmas appear most commonly in
“thermally-limited” settings where melting cannot proceed to
high enough degrees to make basalt. Such settings include
areas where adiabatic ascent is inhibited by thick lithospheres
(cratons, early stages of continental rifting), marginal to
plumes in the early and late stage of ocean island formation,
the final stages of a dying subduction zone, or in areas of rigid
lithosphere where heating can only be accomplished by
conduction from below. This marginal melting regime
enhances the contribution from easily fusible metasomatic
components in the source if they are present.
Mineralogical Magazine
RICHARD W. CARLSON1 AND MATTHEW G. JACKSON2
Department of Terrestrial Magnetism, Carnegie Institution of
Washington, 5241 Broad Branch Road, NW, Washington,
DC 20015 USA, ([email protected])
2
Department of Earth Sciences, Boston University, 675
Commonwealth Ave. Boston, MA 02215 USA,
([email protected])
1
Among the compositional components identified in the
mantle, most attention has been devoted to those components
produced by continental and oceanic crust production and
recycling. “Primitive mantle” appears in most models of
mantle compositional variation, but usually in the abstract
sense in that few, if any, samples of oceanic basalt have all the
characteristics expected for a melt of the model primitive
mantle that is assumed to have chondritic relative abundances
of the refractory lithophile elements. For example, the high
3
He/4He component may sample a reservoir preserving
primitive mantle noble gas characteristics, but at the same
time generally has positive !Nd and often has Pb isotopic
composition plotting well to the right of the Geochron.
PREMA, for “prevalent mantle” was coined by Zindler and
Hart (1986) early in the investigation of mantle isotopic
variation as the most common isotopic component seen not
only in ocean island basalts but in both continental and
oceanic large igneous provinces and as a component in many
intraoceanic island arc lavas.
This component largely
vanished from the discussion of mantle compositional
variation in part because its origin was unclear – it could not
be primitive mantle because it did not have chondritic Nd or
Hf isotopic composition and it might just be some “most
likely” mixture between depleted mantle and enriched
recycled components. The elevated 142Nd/144Nd of all postHadean igneous rocks on Earth, however, suggests that
primitive mantle has Nd, and by inference Sr and Hf, isotopic
compositions in the realm of what traditionally has been called
depleted mantle. We use the trace element characteristics of
Baffin Island and Ontong-Java lavas that have isotopic
compositions closest to those expected for the non-chrondritic
primitive mantle to examine how this reservoir was produced
early in Earth history. We also explore the consequences of a
non-chondritic primitive mantle for such issues as the relative
fraction of DMM and PREMA in the current mantle and the
role of the primitive mantle in the origin of the massive
volcanism associated with large igneous provinces.
www.minersoc.org
Goldschmidt Conference Abstracts
In silico, physiological, and proteomic
cost-benefit analysis of
resource-limited microbial growth
ROSS P. CARLSON*, REED L. TAFFS AND
JAMES FOLSOM,
Deparment of Chemical and Biological Engineering, Montana
State University, Bozeman, 59717 USA,
([email protected])
Evolutionary selection has produced fit microbes with
robust and often redundant metabolic network functionality.
Maintaining and regulating network redundancy represents a
substantial resource burden especially in nutrient limited
environments and therefore needs to be off set by fitness
advantages. A genome enabled in silico methodology was
developed and experimentally tested which quantifies
molecular-level, resource allocation tradeoff strategies that
permit competitive cellular functioning under a continuum of
nutrient availabilities. The approach decomposed a metabolic
network into a complete listing of non-divisible,
mathematically-defined biochemical pathways which were
then used to identify all potential strategies for investing
limiting resources like iron and nitrogen into the genome
encoded metabolic machinery. The tabulated enzymatic
resource investment requirements for each distinct
biochemical pathway were examined in concert with the
pathway’s efficiency at converting substrate into biomass. The
analysis identified the most competitive molecular-level
tradeoffs between pathway resource requirements and
metabolic efficiency; allocating limiting resources to perform
one function well came at the cost of performing another
metabolic function well. In silico predictions were evaluated
experimentally using physiological and proteomic data
collected from iron- or nitrogen-limited Escherichia coli
chemostat cultures. Experimental chemostat data was
consistent with in silico theory and illustrated that under ironand nitrogen-limited conditions E. coli regulates its
metabolism to invest the limiting resource competitively at the
cost of optimal biomass yields on electron donor. The study
highlights a fundamental evolutionary and metabolic design
paradigm for competitive network structure and control.
Mineralogical Magazine
625
Solubility as a determinant of rates of
intergranular diffusion in
metamorphic rocks
W.D. CARLSON
Department of Geological Sciences, University of Texas at
Austin, Austin TX 78712 USA
([email protected])
Rates of intergranular diffusion in metamorphic rocks are
principally determined not by temperature, but instead by the
properties of the intergranular medium, particularly those
properties that govern the solubility of the diffusing species.
Quantitative comparison of length scales and time scales
for metamorphic reaction in natural examples reveals
extremely large variations in rates of intergranular diffusion
for Al among systems with different H2O activities. For
instance, at 600 °C the effective diffusion coefficient for Al
(m2·sec-1) is 10-18.8 in fluid-saturated systems, 10-22.5 in
hydrous-but-fluid-undersaturated systems, and 10-25.4 in
anhydrous systems. Thus even at constant temperature, Al
diffusivities can range across 6 to 7 orders of magnitude
depending on the character of the intergranular medium.
In fluid-saturated systems, garnet zoning—which monitors
the length scale of chemical equilibration during growth—
shows that intergranular solubilities controlled by
characteristics of the fluid itself (H2O/CO2 ratios, availability
of ligands for complexation, pH) can exert greater influence
on diffusivities than temperature. As a case in point, the nature
of compositional zoning in garnet from Harpswell Neck,
Maine, varies markedly from cores to rims. For Mn, Fe, and
Mg, many crystals have irregular, patchy distributions in their
cores that give way to smooth, concentric zoning in their outer
rims. In contrast, zoning of Ca and Y is comparatively smooth
and concentric throughout these crystals. Rims of all crystals
share equivalent concentrations of all elements. Raman
spectrometry of fluid inclusions demonstrates that growth of
garnet cores took place in the presence of a CO2-rich fluid,
whereas growth of garnet rims took place in the presence of an
H2O-rich fluid. Thus the patterns of garnet zoning imply that
low solubility for Mn, Fe, and Mg and high solubility for Ca
and Y in a CO2-rich fluid restricted the length-scales of
equilibration for the former and expanded them for the latter
during the growth of garnet cores; transition to an aqueous
fluid with relatively high solubility for all elements then led to
rock-wide equilibration for all during growth of garnet rims.
Differential solubility of cations in fluids of variable composition is therefore a fundamental control on rates and scales of
intergranular diffusion.
www.minersoc.org
626
Goldschmidt Conference Abstracts
Structural changing control of
potassium saturated smectite at high
pressures and high temperatures:
Application for subduction zones
L.C. CARNIEL, R.V. CONCEIÇÃO AND N.DANI
Geoscience Institute, UFRGS, Porto Alegre – RS, Brazil.
([email protected] [email protected]
[email protected])
The lithospheric mantle is characterized by pressure
ranges from ~ 2.0 and ~ 7.7 GPa and a specific mineralogy
and composition. This region can be re-hydrated and reenriched in incompatible elements (eg. potassium) through
subduction processes that bring pelagic material, composed of
clay minerals and other phyllosilicates, into these regions.
These minerals act as carriers of water and incompatible
elements, re-enriching the lithospheric mantle as they are
destabilized. Then, simulating conditions of high pressure and
temperature in potassium enriched smectite would help to
check the stability field of this mineral and its transformations
during the process of subduction. This research focuses on the
construction of a phase diagram of smectite, previously
saturated with potassium at different temperatures and
pressures. We performed experiments in smectite under
pressures between 2.5 and 4.0 GPa and at different
temperatures (400°C to 700°C). From our results, we conclude
that at 2.5 GPa pressure, which is about 75 km depth in the
mantle, the clay mineral transform into a new phase at 500° C
that correspond to the illite. At higher pressures, we conclude
that at 4.0 GPa pressure, equivalent to 120 km depth, the same
transformation occurs at 400°C. Such results aid new
information to understand the dehydration of pelagic
sediments in a process of subduction, and the mobility of some
incompatible elements in such tectonic setting.
Mineralogical Magazine
Elasticity and anelasticity of relaxor
ferroelectrics
M.A. CARPENTER1*, J.F.J. BRYSON1, E.H. KISI2,
S.M. FARNSWORTH2 AND G. CATALAN3
Dept. of Earth Sciences, Downing St., Cambridge CB2 3EQ
(*correspondence: [email protected])
2
School of Engineering, The University of Newcastle,
Callaghan NSW 2308, Australia
3
Campus Universitat Autònoma de Barcelona, ICREA,
Bellaterra 08193 Spain
1
The elastic behaviour of ferroelectric and relaxor
ferroelectric materials makes an interesting contrast with that
observed in association with ferroelastic phase transitions in
minerals, though the same basic principles apply. Softening of
the bulk and shear moduli of polycrystalline samples occurs in
the high temperature structure as a consequence of dynamical
effects, there are marked elastic anomalies associated with the
phase transition, and anelastic losses arise due to mobile
transformation microstructures. Distinctive features of relaxor
ferroelectric perovskites are frequency-dependent softening
and acoustic losses associated with freezing of polar
nanoregions (PNR’s), together with a large degree of softening
of shear elastic constants due to condensation of static PNR’s
in the stability field of the paraelectric phase. The latter occurs
ahead of the transition to a long range ordered ferroelectric
structure. These distinctive features have been investigated by
Resonant Ultrasound Spectroscopy (RUS) measurements of
polycrystalline Pb(Mg1/3Nb2/3)O3 (PMN) and single crystals of
0.955Pb(Zn1/3Nb2/3)O3-0.045PbTiO3 (PZN-PT). In PMN the
pattern of the elastic compliance as a function of temperature
mirrors the real part of the dielectric constant and the inverse
mechanical quality factor mirrors tan#, showing that a key
aspect of PNR formation is the development of local strain
fields. In PZN-PT, there is a large difference in the shear
elastic constants between poled and unpoled crystals in the
stability fields of the rhombohedral and tetragonal phases and
well into the stability field of the cubic phase. This signifies
that the PNR’s themselves develop a stable microstructure
which can be polarised and which gives rise to acoustic losses
in much the same way as a conventional ferroelectric
microstructure. Central to all this behaviour, as with other
types of phase transitions, including order/disorder, displacive,
magnetic transitions and changes in spin state, is the coupling
of strain with some primary order parameter or with
microstructure.
www.minersoc.org
Goldschmidt Conference Abstracts
Evaluating sources and transport of
zinc and cadmium and their
complexing ligands in the Atlantic
and Pacific Oceans
G. CARRASCO1*, L.A. DUFFAUT-ESPINOSA2,
P.L. MORTON3 AND J.R. DONAT4
Earth, Atmos. and Planet. Sciences Dept., MIT, Cambridge,
MA, USA. (*correspondence: [email protected])
2
Electrical and Computer Engineering Dept., Johns Hopkins
University, Baltimore, MD, USA. ([email protected])
3
Earth, Ocean and Atmos. Sciences Dept., Florida State
University, Tallahassee, FL, USA. ([email protected])
4
Chemistry and Biochemistry Dept., Old Dominion
University, Norfolk, VA, USA. ([email protected])
1
Introduction and Methods
Using Anodic Stripping Voltammetry [1], the
complexation and chemical speciation of Zn and Cd has been
determined in the water column in the Western North Pacific,
the Equatorial South Atlantic as well as in the Elizabeth River
and the Chesapeake Bay waters and benthos. Using a novel
mathematical interpretative tool (Titration Data Interpreter)
that allows for precise, non-biased ligand parameter
optimization of the Gerringa linearization [2], the speciation of
these two metals data was calculated.
Discussion
The results obtained in these oceanic regions indicate
marginal seas and other pointed sources provide both metals
and strong ligands, combining riverine, terrestrial, marine and
anthropogenic matter, as recent literature suggests [3-7]. The
ligands are transported and decay with time along water
masses in both Atlantic and Pacific Oceans, implying
connections to ligands produced the water formation regions
[3,7,8] and from estuarine origin. A consortium of strong
ligands complexes these two metals, affecting their chemical
speciation in surface, intermediate and deep waters. The
ramifications of this phenomenon on the close and remote
upwelling of potentially limiting concentrations of
bioavailable Zn and Cd will be discussed.
Amino sugar and amino acid
degradation and transformation in
two lakes with different redox state
D. CARSTENS1,2*, K.E. KÖLLNER1,2, H. BÜRGMANN1 AND
C.J. SCHUBERT1
Swiss Federal Institute for Aquatic Science and Technology
(Eawag), 6047 Kastanienbaum, Switzerland
(*correspondence: [email protected])
2
Institute of Biogeochemistry and Pollutant Dynamics, ETH
Zürich, 8092 Zürich, Switzerland
1
Transformation and degradation processes of organic
matter in aquatic systems play a key role in the global carbon
cycle. Although lakes seem to store carbon efficiently, little is
known about organic matter degradation in these systems. In
order to study the fate of organic nitrogen compounds in
lacustrine systems under different redox conditions, Lake
Brienz (oligotroph, fully oxic) and Lake Zug (eutrophic,
stratified oxic/anoxic) were investigated. Profiles of
particulate amino sugar and amino acid concentrations were
measured in the water column of both lakes as well as in the
first centimeters of the sediments by gas chromatography.
Decreasing carbon normalized amino sugar yields with
increasing water depth indicated enhanced degradation of
amino sugars compared to the bulk organic matter in both
lakes. Under oxic conditions the degradation was more
pronounced. The amino sugar composition of the particulate
organic matter revealed a replacement of planktonic biomass
by heterotrophic mircoorganisms from the upper water layers
towards the lake bottom. The contribution of bacteria to the
organic carbon was estimated using the amino sugar muramic
acid, which is unique to bacteria as part of their cell wall. In
the oligotrophic lake 0.8-11% of the organic carbon derived
from bacteria and in the eutrophic lake this contribution was
0.3-5%. These findings underline that bacteria are not only
drivers of organic matter degradation in lacustrine systems but
also a significant source of organic matter themselves.
[1] Bruland (1989) Limnol. Ocean. 34, 269-285. [2] Gerringa
et al. (1995) Mar. Chem. 48, 131-142. [3] Nishioka et al.
(2007) J. Geophys. Res. 112, C10012. [4] Vangriesheim et al.
(2009) DSR-II doi:10.1016/j.dsr2.2009.04.002 [5] Lam &
Bishop (2008) Geophys. Res. Lett. 35, LO7608. [6] Hernes &
Benner (2002) DSR-I 49, 2119-2132. [7] Baars & Croot
(2011) DSR-II doi:10.1016/j.dsr2.2011.02.003. [8] Ellwood &
van den Berg (2000) PMar. Chem. 68, 295-306.
Mineralogical Magazine
627
www.minersoc.org
628
Goldschmidt Conference Abstracts
On the mass independent
fractionations of O, Hg, Si, Mg and
Cd during open-system evaporation
or thermal decomposition
P. CARTIGNY1*, J.M. EILER2, P. AGRINIER1
1
AND N. ASSAYAG
Stable Isotope Laboratory of IPG-Paris, France.
(*correspondence : [email protected])
2
Division of Geological and Planetary Sciences, California
Institute of Technology, Pasadena, CA 91125, USA.
1
Many experiments in which an element or a mineral is
evaporated or thermally decomposed under vacuum are known
to consistently display unexpected behaviors. These include
too low rates of evaporation, smaller (i.e. closer to 1) than
predicted fractionation factors, and an inconsistent behavior of
the stable isotope ratios of a given element (i.e. massindependent fractionation). This applies to many elements
including O, Hg, Si, Mg and Cd.
We present interpretations for a series of earlier
observations, including experiments by Miller et al. (2002) in
which mass-independent O isotope fractionations are
produced during thermal decomposition of carbonates [1], and
the finding of Estrade et al. (2009) showing an unexpected
slope in a plot of &199Hg vs &201Hg (close to 1.2 instead of 2.4)
during open-system evaporation of Hg [2].
These and related results can be explained if a fraction
(usually a few to several tens of percent) of the evaporated
compounds actually forms (or re-equilibrate) under conditions
of isotope equilibrium, the remaining fraction obeying kinetic
fractionation of its stable isotopes. This is the mixing of the
that results in the appearance of mass-independence, rather
than the action of a novel isotope effect having non-cannonical
mass law.
[1] Miller M.F. et al. (2002) PNAS 99, 10988–10993. [2]
Estrade N. et al. (2009) Geochim. Cosmochim. Acta 73, 26932711.
Howardite noble gases as indicators
of asteroid surface processing
J.A. CARTWRIGHT1, D.W. MITTLEFEHLDT2,
J.S HERRIN2 AND U. OTT1
Max Planck Institut für Chemie, J.-J.-Becher-Weg 27, 55128
Mainz, Germany ([email protected])
2
NASA/Johnson Space Centre, Houston, Texas, USA.
1
Introduction and Research Objective:
The HED (Howardite, Eucrite and Diogenite) group
meteorites likely originate from the Asteroid 4 Vesta [1] - one
of two asteroid targets of NASA’s Dawn mission [2]. Whilst
Howardites are polymict breccias of eucritic and diogenitic
material that often contain “regolithic” petrological features,
neither their exact regolithic nature nor their formation
processes are well defined [3-4]. As the Solar Wind (SW)
noble gas component is implanted onto surfaces of solar
system bodies, noble gas analyses of Howardites provides a
key indicator of regolithic origin. In addition to SW, previous
work by [5] suggested that restricted Ni (300-1200 µg/g) and
Al2O3 (8-9 wt%) contents may indicate an ancient well-mixed
regolith. Our research combines petrological, compositional
and noble gas analyses to help improve understanding of
asteroid regolith formation processes, which will play an
intergral part in the interpretation of Dawn mission data.
Methodology:
Following compositional and petrological analyses [4,6],
we developed a regolith grading scheme for our sample set of
30 Howardites and polymict Eucrites [4]. In order to test the
regolith indicators suggested by [5], our 8 selected samples
exhibited a range of Ni, Al2O3 contents and regolithic grades.
Noble gas analyses were performed using furnace step-heating
on our MAP 215-50 noble gas mass spectrometer.
Discussion of Results:
Of our 8 howardites, only 3 showed evidence of SW noble
gases (e.g approaching 20Ne/22Ne ~ 13.75, 21Ne/22Ne ~ 0.033
[7]). As these samples display low regolithic grades and a
range of Ni and Al2O3 contents, so far we are unable to find
any correlation between these indicators and “regolithic”
origin. These results have a number of implications for both
Howardite and Vesta formation, and may suggest complex
surface stratigraphies and surface-gardening processes.
[1] Drake M.J. (2001) MAPS 36:501-513. [2] Rayman, M.D.
et al. (2006) Acta Astronautica 58:605-616. [3] Mittlefehldt,
D.W. et al. (1998) Rev. Min. 36: 4.1-4.195. [4] Cartwright,
J.A. et al. (2011) LPSC XLII (abs. # 2655). [5] Warren, P.H. et
al. (2009) GCA 73:5918-5943. [6] Mittlefehldt, D.W. et al.
(2010) LPSC XLI (abs. #2655). [7] Grimberg, A. et al. (2008)
GCA 72:626-645.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Magnetic susceptibility of sands from
a river beach for forensic applications
Á. CARVALHO1, H. RIBEIRO1, A. GUEDES1,2,
H. SANT’OVAIA1,2, I. ABREU1,3 AND F. NORONHA1,2*
Centro de Geologia da Universidade do Porto (CGUP),
Portugal
2
Departamento de Geociências, Ambiente e Ordenamento do
Território da Faculdade de Ciências da Universidade do
Porto, Portugal
3
Departamento de Biologia da Faculdade de Ciências da
Universidade do Porto, Portugal (*[email protected])
1
Soil studies are often undertaken in forensic investigation
because its particles are normally tranferred to the surfaces in
contact with them, providing important information. Soil is
composed by organic and inorganic materials and its history is
reflected in its bio-physicochemical characteristics, including
low-field magnetic susceptibility (MS). MS is defined as the
ratio of the material magnetization (per unit mass) to the weak
external magnetic field, and in soils, it is directly proportional
to the quantity, composition and grain size of minerals in the
sample (which can be diamagnetic, paramagnetic or
ferromagnetic species).
In order to investigate the variability of this property in
Areinho, a fluvial river beach in Porto region (Northern
Portugal), twenty four samples were collected along a transect
perpendicular to the river side and prepared for magnetic
susceptibility analysis. MS was measured on 1g of dry bulk
samples, applying them an external magnetic field of 300
A/m, and a Kappabridge model KLY4S of Agico balance
equipped with the Sumean software was used. Before each
measurement the equipment was calibrated. The MS of
Areinho sands is low with values ranging between
0.68x10-8m3/Kg and 18.09x10-8m3/Kg which is an agreement
with its mineralogical composition. All measurement results
were reproducible. From this study we conclude that MS
protocol is suitable for the analysis of sands with the
advantage of being fast and non-destructive.
Acknowledgements: The first author benefits from a PhD
scholarship (SFRH/BD/61460/2009) funded by Fundação da
Ciência e Tecnologia (QREN-POPH-Type 4.1-Advanced
Training, subsidized by the European Social Fund and national
funds MCTES). The authors acknowledge the funding of FCT
- POCI 2010 to CGUP.
Mineralogical Magazine
629
Radionuclides in uranium milling
tailings and environment remediation
F.P. CARVALHO, J.M. OLIVEIRA AND M.MALTA
Instituto Tecnológico e Nuclear, E.N. 10, 2686-953 Sacavém,
Portugal ([email protected])
The environmental and public health risks posed by legacy
uranium mine sites and milling tailings in Portugal was
assessed in order to allow for decision making regarding
environmental remediation and for radiological protection
measures of the population.
Most of old uranium mine sites did not pose noticeable
ionizing radiation and contamination risks to the environment
and population, especially the sites operated as open pits and
without in situ chemical operations. The mines where in situ
ore leaching with sulfuric acid was operated and the ore
milling tailings are the sites with higher ambient radioactivity
and contamination with radioactive and stable metals [1]. Over
some waste piles the radiation dose attained 30 mSv y-1, higher
than the annual limit for members of the public, 1 mSv y-1.
Confinement and coverage of these uranium waste piles was
necessary and allowed for reducing radon exhalation, dispersal
of radioactive materials in soils, and abatement of surface
runoff and radionuclide leaching with acid drainage. in situ
formation of H2SO4 in waste piles still generates radioactive
leachates in underground mines and in milling tailings that
require continued treatment. Irrigation of agriculture plots in
the mine areas with mine drainage and water from
contaminated wells is the main pathway to transfer
radionuclides, especially 226Ra, into locally grown vegetables
and into the food chain [1,2].
Milling tailings with high radioactivity must be confined
to reduce dispersion of radionuclides and exposure of biota
and the public. Water from rivers that received past discharges
of acid mine drainage have contaminated sediments that may
require removal. Mine drainage and underground waters in the
area of former mines shall be monitored to avoid exposure of
the public to acid, metals and radionuclides. Withouth suitable
monitoring and abatement measures, radiological exposure of
members of the public may be many times about radiation
exposure legal limits.
[1] FP Carvalho, J M Oliveira, I Lopes, A Batista, J Environ
Radioactivity 98(2007):298-31. [2] FP Carvalho, JM Oliveira,
M Malta, J Radional Nuc Chemistry 281 (2009):479-484.
www.minersoc.org
630
Goldschmidt Conference Abstracts
Geochemistry of groundwater from
Graciosa Island (Azores):
A contribution to the hydrothermal
system conceptual model
M.R. CARVALHO1, P.M. CARREIRA2, J.M. MARQUES3,
G. CAPASSO4, F. GRASSA4 AND J.C. NUNES5
Universidade de Lisboa, Faculdade de Ciências, Depart.
Geologia/CeGUL, Portugal
2
Instituto Tectonológico e Nuclear, Lisboa, Portugal
3
Instituto Superior Técnico, Lisboa, Portugal
4
Istituto Nazionale di Geofisica e Vulcanologia, Sezione di
Palermo, Palermo, Italy
5
Universidade dos Açores & INOVA Inst., Azores, Portugal
1
Graciosa island is located in the Azores Archipelago,
along the so-called Terceira Rift, a major tectonic structure
that makes the NE boundary of the Azores Plateau. In general
terms, it includes a basaltic plataform on the NW and a silicic
poligenetic volcano with caldera on the SE, the Graciosa
Caldera Volcano. This volcano has produced significant
tephra falls, pyroclastic flows, lahars, and lava flows, both of
basaltic s.l. and trachitic s.l. composition.
The hydrothermal system shows fumarolic emissions
inside the volcano caldera and thermal springs located along
the shoreline. This system is exploitated in a thermal building
through shallow and deep (110 m) boreholes, near the coast.
In Graciosa two types of Na-Cl groundwater systems can
be identified: 1) a cold one emerging at springs and exploited
by wells for public water supply, and 2) a hydrothermal
system with temperatures around 40-44 ºC. The cold
groundwaters have pH higher than 7 and different degree of
mineralization, according to the proximity to the sea. The
thermal waters show mixing with seawater, pH varying
between 6.20 and 6.94, 166 mg/L of SiO2, and significant
concentration of metals, such as Mn, Fe, Co, Ni, Cu and Zn.
The thermal water mineralization varies strongly, showing EC
from 8.87 mS/cm (shallow water) to 47.4 mS/cm (deeper
water). The higher mineralized water is rich in CO2(g), with
2130 mg/L of total dissolved CO2. Geothermometers
application reveals aquifer temperature ' 167 ºC and
immature/mixed waters, not reaching complete equilibrium
with reservoir rock.
The geochemistry of the thermal waters indicates the
occurrence of seawater/host rock interaction processes at high
temperature and slightly acid conditions, favored by CO2(g)
input, and a different degrees of mixing with cold and shallow
groundwaters.
Mineralogical Magazine
Geochemistry of S-type granitic rocks
from the Valongo area
(Northern Portugal)
P.C.S. CARVALHO1*, A.M.R. NEIVA1,
M.M.V.G. SILVA1 AND F. CORFU2
Geoscience Centre and Department of Earth Sciences,
University of Coimbra, 3000-272 Coimbra, Portugal
(*correspondence: [email protected])
2
Department of Geosciences, University of Oslo, PB1047
Blindern, N-0316, Norway
1
Variscan peraluminous granitic rocks crop out at the
eastern limb of the Valongo anticline, located about 18 km at
east of Oporto, in the Dúrico - Beirão region, northern
Portugal and Central Iberian Zone of the Iberian Massif.
The
mediumto
coarse-grained
porphyritic
biotite>muscovite granite (G1) intruded Ordovician and
Silurian metasediments and produced a contact metamorphic
aureole. The medium-grained porphyritic biotite ' muscovite
granodiorite (G2) intruded the earlier granite and the contact is
by faulting. The fine-grained porphyritic biotite>muscovite
granodiorite (G3) intruded the other two granitic rocks.
Granite G1 and granodiorite G2 are late-D3, whereas
granodiorite G3 is post-D3. The U-Pb ages for zircon and
monazite, obtained by ID-TIMS, are 309.6±1.0 Ma for G1,
307.0 ± 3.2 Ma for G2 and 305.1± 0.4 Ma for G3 and 587 Ma
for inherited zircon cores from G2 and G3. Variation diagrams
show that G3 has higher TiO2, total FeO, MgO, CaO, Zr, Ba,
Th, Ce contents and lower SiO2, Li, Rb contents than G1 and
they define independent trends. G2 is not related to G1.
Granite G1 and granodiorite G3 have similar (87Sr/86Sr)i of
0.7085, #NdT -6.64 (G1) and -6.92 (G3) and (18O 11.36 ‰
(G1) and 10.90 ‰ (G3). Therefore, they are derived by partial
melting of the same metasedimentary materials, containing
Neoproterozoic detritus, but G3 results from a higher degree
of partial melting than G1. Granodiorite G2 results from a
distinct granitic magma and is derived by partial melting of
metasedimentary materials containing Neoproterozoic detritus,
as it has (87Sr/86Sr)307 of 0.7080, #Nd307 of -7.06 and (18O of
11.31 ‰. The three granitic rocks are of S-type.
www.minersoc.org
Goldschmidt Conference Abstracts
Systematic variations in argon
diffusion in feldspars
W.S. CASSATA12, P.R. RENNE12 AND D.L. SHUSTER12
1
2
Berkeley Geochronology Center, USA
University of California, Berkeley, USA
Feldspars are commonly used in 40Ar/39Ar studies to
constrain the thermal evolution of meteorites, mountain belts,
intrusive magmatic bodies, and a host of other Earth and
planetary processes. Although the kinetics of Ar diffusion in
K-feldspars have been extensively researched, comparably
little work has been published on plagioclase feldspars, despite
their being the primary host of potassium in most chondritic,
lunar, and Martian meteorites and many terrestrial igneous
bodies. Similarly, little is known of the potential effects of
composition and structural state on Ar diffusion kinetics, or
the extent to which diffusion might be anisotropic.
In this study, ~100 step-heating diffusion experiments
were conducted on feldspars that range in composition from
nearly pure orthoclase to nearly pure anorthite, with the bulk
of the samples being plagioclase feldspars. These experiments
reveal systematic variations in diffusive behavior that appear
to be closely related to composition and microstructure. For
example, plagioclase crystals having compositions between
An50 and An90 typically yield Arrhenius arrays with
pronounced upward curvature between 600 and 800 °C, the
opposite of that commonly observed on Arrhenius plots from
K-feldspars inferred to have multiple diffusion domains.
Plagioclase crystals with compositions <An50 yield linear
Arrhenius arrays that give way to downward curvature
between 600 and 1000 °C, where the temperatures at which
linearity ceases appear to depend on the composition of the
sample and the heating schedule. Brecciated and
microstructurally complex plagioclase crystals exhibit
Arrhenius arrays consistent with multiple diffusion domains.
Preliminary experiments on cleavage flakes indicate that
diffusion may be faster in the [001] crystallographic direction
than [010], and additional experiments are underway to
confirm this finding. Activation energies for plagioclase and
K-feldspars span a large range, from ~160-300 kJ/mole.
Arrhenius plots for Ar diffusion in plagioclase appear to
reflect a confluence of intrinsic diffusion kinetics and
structural ordering-disordering that occurs during prolonged
step-heating. These data indicate that Ar diffusivity is
intimately related to composition and microstructure in
plagioclase. As such, there is no broadly applicable set of
diffusion parameters that can be utilized in thermal modeling.
Sample-specific data are required.
Mineralogical Magazine
631
Tracking the magmatic evolution of
an island arc volcano: Insights from a
high-precision Pb isotope record of
Montserrat, Lesser Antilles
M. CASSIDY*, R.N. TAYLOR, M.J. PALMER AND
J. TROFIMOVS
National Oceanography Centre, Southampton, University of
Southampton, Waterfront Campus, European Way,
Southampton SO14 3ZH
(*correspondance:[email protected])
It is rare to have a chance to examine the magmatic
evolution of an island arc volcano over a period of millions of
years. The volcanic succession exposed on Montserrat
provides such an opportunity, extending from the 2 Ma
andesites of the Silver Hills complex through to the youngest
dome collapse of the Soufrière Hills volcano (February 2010).
In this study we present new trace element, Sr, Nd and highprecision double spike Pb isotope data taken through
Montserrat’s time sequence. As well as from subaerial
locations, we have collected samples from marine sediment
cores, as significant volumes of pyroclastic material have
ended up in the Caribbean Sea.
Each of Montserrat’s volcanic groups; South Soufrière
Hills (SSH), Soufrière Hills, Centre Hills and Silver Hills, can
be clearly discriminated using trace element and isotopic
parameters. Furthermore, the SSH can be divided into two
suites: A and B, combining trace elements and Pb isotopes.
The trends in trace elements and isotopes suggest some
variability in fluid and sediment addition over time. The SSH
in particular has a greater slab fluid signature as indicated by
elevated Pb/Ce, but less sediment addition than the other
volcanic centres. 206/204Pb against )7/4 and )8/4 diagrams
show that Montserrat falls along two differing trends, one
defined by the SSH volcanic region and the second trend
defined by the other volcanic regions on Montserrat (Silver
Hills, Centre Hills and Soufrière Hills). Furthermore, the SSH
volcanic centre differs noticeably in trace elements and
isotope ratios. This demonstrates that the source which
generated the SSH magmas is different to the source of the
other volcanics on Montserrat. Both isotopic trends point to an
enriched mantle source underneath Montserrat. Samples from
the current period of activity will be discussed including the
presence of mafic enclaves within the current eruption.
www.minersoc.org
632
Goldschmidt Conference Abstracts
Metamorphic and geodynamic
evolution of the high-grade units of
Mundão – Sátão (Northern Portugal)
P. CASTRO1, T. BENTO DOS SANTOS1,2*, C. MEIRELES1,
A.J.D. SEQUEIRA1 AND N. FERREIRA1
LNEG – Laboratório Nacional de Energia e Geologia,
Portugal (*correspondence: [email protected])
2
Centro de Geologia, Universidade de Lisboa, Portugal
1
The Mundão – Sátão sector (N Portugal) is composed of
syn- to post-D3 Hercynian granitoids and by pre-Ordovician
metasediments, belonging to the Schist – Greywacke Complex
of the Iberian Central Zone. The metasediments comprise two
low-grade sequences (chlorite to biotite zones), Ponte
Chinchela and Nelas Units, separated by the exotic high-grade
tectonometamorphic sequence of the Casinha Derrubada Unit
(CDU) [1] that includes three tectonic slices separated by
thrusts, from bottom to top: a) micaschists and mylonites with
sillimanite; b) mylonites with porphyroclastic staurolite; and
c) biotitic micaschists with garnet.
The CDU is a MP metamorphic sequence associated with
the establishment of the metamorphic peak during D2. Late
retrograde evolution is evidenced by prismatic andalusite
pseudomorphs after porphyroclastic staurolite, and andalusite
+ biotite coronas around staurolite rims. These textural
evidence are coeval with the reorientation of staurolite
prismatic crystals from sub-horizontal to sub-vertical and late
incipient migmatization by decompression and crossing of the
granite wet solidus curve during D3 exhumation phase.
The observed petrological/geochemical features and the
paragenetic evolution of the CDU high-grade rocks imply that
this area is not a typical contact metamorphic sequence [2] or
a complete Barrovian-type sequence arround an anatectic
dome [3]. The new data points out the existence of nettectonic control on the emplacement of the high-grade rocks at
this sector and that the CDU is an incomplete Barrovian-type
sequence from MT to HT, subsequently exhumed onto a lowgrade metamorphic sequence. The evidence suggest that the
tectonometamorphic evolution of the CDU rocks is consistent
with a clockwise P-T-t path, involving: 1) a metamorphic peak
at T ~ 600 – 700 ºC and P ~ 6 – 7 kbar; 2) significant
decompression to 2 – 3 kbar; 3) rapid cooling as the result of
thermal readjustment to higher crustal levels.
[1] Ferreira et al. (2009) Carta Geol. Portugal (Folha 17-A),
LNEG. [2] Esteves (2006) Unpub. MSc Thesis, Univ. Aveiro,
113. [3] Valle Aguado et al. (2010) e-Terra, 16, 9, 1-4.
Mineralogical Magazine
Surface transformations and element
cycling resulting from interfacial
Fe(II)-Fe(III) self exchange
J.G. CATALANO1*, A.J. FRIERDICH1, Y. LUO1,2,
P. FENTER3, C. PARK4 AND K. M. ROSSO5
Earth & Planetary Sciences, Washington Univ., St. Louis,
MO 63130 USA (*correspondence: [email protected])
2
Energy, Environmental, and Chemical Engineering,
Washington Univ., St. Louis, MO 63130, USA
3
Chemical Sciences and Engineering Division, Argonne
National Laboratory, Argonne, IL 60439 USA
4
HPCAT, Carnegie Institution of Washington, Argonne, IL
60439 USA
5
Chemical & Materials Sciences Division, Pacific Northwest
National Laboratory, Richland, WA 99352 USA
1
Biogeochemical iron cycling induces coupled electron
transfer and atom exchange between aqueous Fe(II) and
Fe(III) oxide surfaces [1-4]. Our recent work [5] has explored
the molecular-scale structural transformations of hematite
surfaces that result from this process. Under both acidic (pH 3)
and neutral (pH 7) conditions Fe(II) induces layer-by-layer
dissolution or growth of the hematite (110) and (012) surfaces.
In contrast, the hematite (001) surface develops a <1 nm-thick
discontinuous film that displays structural relaxations different
from the underlying surface. This demonstrates that Fe(II)
activates localized growth and dissolution independent of
macroscopic Fe(II) adsorption.
We have further explored the effect of this process on the
fate of the structurally-compatible trace element Ni. For both
hematite and goethite we observe that aqueous Fe(II) induces
the incorporation of adsorbed Ni into the iron oxide structure.
In addition, pre-incoporated Ni is released into solution by
Fe(II). The rates of release and incoporation are orders of
magnitude slower than the rate of macroscopic Fe(II)
adsorption but comparable to iron isotope equilibration [3].
We propose that Fe(II) catalyzes a thermodynamicallycontrolled redistribution of Ni among the mineral bulk,
mineral surface, and aqueous solution. This work has
implications for the validity of proxies for ocean composition
on the early Earth and micronutrient and contaminant
availability in soil, sedimentary, and aquatic systems.
[1] Williams & Scherer (2004) Environ. Sci. Technol. 38,
4782-4790. [2] Yanina & Rosso (2008) Science 320, 218-222.
[3] Handler et al. (2009) Environ. Sci. Technol. 43, 11021107. [4] Rosso et al. (2010) Environ. Sci. Technol. 44, 61-67.
[5] Catalano et al. (2010) Geochim. Cosmochim. Acta 74,
1498-1512.
www.minersoc.org
Goldschmidt Conference Abstracts
Reworked Hadean crust in
the ca. 3780 Ma Nuvvuagittuq
supracrustal belt
Colloidal control on the distribution
of major and trace elements in a
small mountain stream (Malaval
catchment, Massif Central, France)
N.L. CATES1, S.J. MOJZSIS1, K. ZIEGLER2
2
AND A.K. SCHMITT
Dept. of Geological Sciences, University of Colorado,
Boulder, CO 80309-0399 USA ([email protected])
2
Dept. of Earth and Space Sciences, University of California,
Los Angeles, CA 90095-1567 USA
C. CATROUILLET1, C. DE BARDON DE SEGONZAC1,
O. POURRET1 AND M. STEINMANN2
1
Variably deformed amphibolites and granitoid gneisses of
the Nuvvuagittuq supracrustal belt (NSB) preserve lower
142
Nd/144Nd ratios than the terrestrial standard. Expressed as
negative #142Nd values, the amphibolites also show a slight
positive correlation in Sm/Nd. Combined 142Nd and 147Sm143
Nd data were used [1] to produce a ca. 4280 Ma isochron;
this could make the NSB amphibolites the oldest preserved
terrestrial rocks by about 300 Myr. Alternatively, the
142
Nd/144Nd signal may be inherited from crustal recycling of
remnant ancient mafic lithosphere and hence it would have no
bearing on the crystallization ages of the amphibolites.
Here we report U-Pb ages for detrital igneous zircons with
rhythmically zoned rounded cores and later metamorphic
overgrowths, extracted from NSB fuchsitic quartzites. We
show that they are statistically indistinguishable from other
~ 3800 Ma zircon ages obtained for transecting felsic gneisses
[2, 3]. The zircon-bearing fuchsitic quartzites show:
i) Elevated whole-rock Cr (>150 ppm) contents, and rounded
chromites with mantling Cr-muscovite, inconsitent with
orthogneiss compositions; ii) Enriched LREECN and mantlenormalized multi-element compositions inconsistent with NSB
chemical sediments (BIFs), but nearly identical to quartzbiotite schists (metaconglomerates) which also host massindependently fractionated sulfur isotopes; iii) Major and trace
elements, including elevated REE, Nb and Ti contents that are
neither compatible with a silicification origin of NSB
amphibolites, nor with hydrothermal quartz veinings; and
iv) Oxygen isotopes consonant with a sedimentary origin.
It is thus improbable that amphibolites of the NSB
represent relict genuine Hadean mafic crust captured in a
supracrustal belt that can be no older than 3780 Myr.
Comparison of detrital and igneous zircon ages from multiple
lithologies in the NSB show that its initial development took
place in under 20 Myr in the Eoarchean. However, our results
do underscore the notion that recycling of volumetrically
significant relict Hadean mafic crust continued to play a role
in Eoarchean crustal processes, in accord with data in [1].
[1] O’Neil et al. (2008) Science 321, 1828-1831. [2] Cates &
Mojzsis (2007) EPSL 255 9-21. [3] Cates & Mojzsis (2009)
Chem. Geol. 261 98-113.
Mineralogical Magazine
633
HydrISE, LaSalle Beauvais, 60026 Beauvais cedex, France
([email protected])
2
UMR 6249 Chrono-Environnement, Univ. Franche-Comté,
25030 Besançon cedex, France
([email protected])
1
Organic and/or inorganic colloids play a major role in the
mobilization and speciation of trace elements in river waters.
Environmental physicochemical parameters (pH, Eh, T, ionic
strength…) are the controlling factors of colloidal
mobilization. Ultrafiltration experiments using small
ultracentrifugal filter devices were performed at different pore
size cut-offs (30 kDa, 10 kDa and 3 kDa) to study the colloidal
control on partitioning of major and trace elements in stream
water [1]. Six sites were sampled in the Malaval stream
catchment from upstream to downstream (Massif Central,
France [2]) during two sampling campaigns (September 2009
and June 2010) and analyzed for major and trace elements,
and organic carbon. In addition to evolution with distance, the
modification of the colloidal pool by water mixing at two
confluences of the Malaval stream with tributaries was also
studied.
The main results of the present study are the following:
most elements behave coherently through time and their
speciation evolves with distance from source. Based on
principal component analysis and hierarchical ascendant
classification performed on the whole ultrafiltration dataset,
three groups of elements with a specific chemical behavior can
be distinguished: (i) a dissolved group (Na, Mg, Si, K, Ca, Rb,
Sr), (ii) a reactive group (Al, Fe, Y, Pb, Cu, Ni, As, U, Zr) and
(iii) an intermediate group (Co). In addition to this statistical
approach one trace element of each group (Sr, Co and Nd) has
been studied in more detail on ultrafiltrated sample fractions
(0.2 µg/L, 30 kDa, 10 kDa and 3 kDa). The results suggest
that (i) the alkalines and alkaline earths are present as
dissolved species, whereas (ii) rare earth elements and some
metallic elements are bound to colloidal material. However,
(iii) a few elements, like cobalt, have an ambivalent behavior:
in some samples they behave like the first group and in others
like the second group.
[1] Pourret et al. (2007) App. Geochem. 22, 1568-1582 [2]
Steinmann & Stille (2008) Chem. Geol. 254, 1-18.
www.minersoc.org
634
Goldschmidt Conference Abstracts
Effects of Laschamp excursion on
cosmogenic isotope production
A. CAUQUOIN1*, J. JOUZEL1 AND G. M. RAISBECK1,2
IPSL / LSCE, UMR CEA-CNRS-UVSQ, CEA Saclay, 91191
Gif-sur-Yvette, France
(*correspondence: [email protected],
[email protected])
2
Centre de Spectrométrie Nucléaire et de Spectrométrie de
Masse, IN2P3-CNRS-Université de Paris-Sud, Bât. 108,
91405 Orsay, France ([email protected])
1
The Laschamp excursion is a period of reduced
geomagnetic field intensity occurring 40.7 ± 1.0 ky ago [3]
During this period, cosmogenic isotope production was
affected not only directly by the reduced magnetic field, but
also due to an increased sensitivity to solar activity. The latter
occurs because a larger fraction of the lower energy
interstellar galactic cosmic ray particles, normally excluded by
the magnetic field, is able to reach the earth’s atmosphere
when the geomagnetic field is reduced. The overall result is a
period of increased cosmogenic isotope (10Be,14C) production
having considerable structure.
The aim of this study is to estimate, using high resolution
(decadal) profiles of 10Be in ice cores from both Antarctica
and Greenland as a proxy for production, input into a 10-box
carbon cycle model, the expected influence of the Laschamp
event on the concentration of 14C in the atmosphere between
37.5 and 45.5 ky BP.
Several cases were tested, from modern carbon cycle (preindustrial) to severely reduced surface-deep ocean exchange
flux [1]. We find that the atmospheric )14C due to increased
production during this period varies from 180 to 300 ‰. This
is considerably smaller than the ~500 ‰ modelled by
Hoffmann et al. [2] between 44-41 ky, which they attribute
mainly to increased production. We believe the main
difference is their use of an inadequate approximation for
production as a function of geomagnetic field intensity.
Hoffmann et al. also deduced an ~500 ‰ increase in
atmospheric &14C from measurements in stalagmites. If such
an increase did indeed occur, we conclude that a substantial
fraction must have resulted from a redistribution of the carbon
cycle.
Environmental geochemistry of
nickel in stream sediments in
Pernambuco State, Brazil
R. CAVALCANTE, E. A. M. LIMA, M. FRANZEN AND
S. S. COSTA
CPRM - Geological Survey of Brazil
(correspondence*: [email protected],
[email protected];
[email protected])
The studied area covers the whole Pernambuco State,
where they were collected 1162 samples of stream sediments
to nickel (Ni). Analyses for environmental geochemistry have
been achieved by the concentration ratios of metal and the
average content in Brazilian standards [1].
The drainage sediments were analyzed by ICP-MS in
fractions <80 mesh. Statistical analysis of dispersion of data
obtained and toxicological reference [1] provided level above
which the Ni may be considered anomalous.
The study shows Ni contents below the background, and
environmentally consistent with the average (18 ppm) below
which is not predictable adverse effects on biota. With the
exception, there are three main areas with few values
exceeding the limit proposed by [1]: (i) western 40-75 ppm
Ni; (ii) center 43-54 ppm Ni; e (iii) east 50-80 ppm. The
above data may correspond to normal values, backgrounds
rocks of the area and may not represent anthropogenic
pollution.
[1] CONAMA 2004. Resol. Nº 344/2004. Web page:
http://www.mma.gov.br
[1] K. Hughen et al. (2006) Quat. Sci. Rev. 25, 3216-3227. [2]
D. L. Hoffmann (2010) Earth Planet. Sci. Lett. 289, 1–10. [3]
B. Singer et al. (2009) Earth Planet. Sci. Lett. 288, 80-88.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Laboratory studies into sea-spray
chemical speciation in
plankton-enriched sea-water
D. CEBURNIS1*, J. OVADNEVAITE1, M. ZACHARIAS2,
J. BIALEK1, S. CONNAN2, M. RINALDI3, C. MONAHAN1,
M.C. FACCHINI3, H. BERRESHEIM1, D.B. STENGEL2 AND
C.D. O’DOWD1
School of Physics and Center for Climate and Air Pollution
Studies, Ryan Institute, National University of Ireland
Galway, Galway, Ireland.
(*correspondence: [email protected] )
2
Botany and Plant Science, School of Natural Sciences, Ryan
Institute, National University of Ireland Galway, Galway,
Ireland.
3
Institute of Atmospheric Sciences and Climate, National
Research Council, Bologna, 20129, Italy.
1
Marine aerosol enrichment by biogenic organic matter
(OM) has been linked to phytoplankton activity [1], thus
having a strong seasonal impact on both the Earth’s albedo
and climate. In addition to a seasonal cycle, sea-spray
generation and its enrichment with OM is a very dynamic
process producing regular OM plumes over N.E. Atlantic [2].
Plankton-enriched seawater contains a complex mixture of
dissolved and particulate organic carbon components (POC
and DOC) producing both water soluble and insoluble organic
aerosol species [3, 4]; this warrants detailed laboratory studies
aimed at establishing a link between observed ambient aerosol
OM and its very primary form.
Laboratory studies using the microalgal species Emiliania
huxleyi, Leptocylindrus danicus and Cylindrotheca closterium
were performed using on-line and off-line analytical
techniques, a sea spray production chamber and an ageing
chamber with day-light and ozone. Under controlled
conditions a sea spray highly enriched in OM was produced
with levels similar to Facchini et al. [3]. HR-ToF-AMS,
1
HNMR and HTDMA techniques confirmed OM composition
of highly hydrocarbon-like, water insoluble OM characteristic
of unsaturated lipids exhibiting low hygroscopic growth
factor. Freshly produced OM, while largely insoluble, was far
less oxidised (less sugars) than the OM reported by Facchini et
al. [3]. Processing with light and ozone continued to support
primary origin of ambient OM.
[1] O'Dowd, C.D., et al. (2004) Nature 431, 676-680. [2]
Ovadnevaite, J., et al. (2011) Geophys. Res. Lett. 38(2),
L02807. [3] Facchini, M.C., et al. (2008) Geophys. Res. Lett.
35(17), L17814. [4] Russell, L.M., et al. (2010) P. Natl. Acad.
Sci. USA 107(15), 6652-6657.
Mineralogical Magazine
635
Mineralogy and geochemistry of
zeolites of pyroclastic deposits in
Northwestern of Tuzgölü Basin
(Turkey)
MUAZZEZ ÇELIK KARAKAYA* AND NECATI KARAKAYA
Selçuk Universitesi Muh.-Mim. Fakültesi Jeoloji Müh. Böl.
Konya, 42079, Türkiye ([email protected])
The Early Miocene volcanic rocks in the Kulu (Konya)Haymana (Ankara) area were classified as andesitic-dacitic
lavas and pyroclastics, and in some cases as trachytic and
trachyandesitic. The zeolitic tuff layers are interbedded with
bentonite layers and rarely silica lenses or thin layers.
Plagioclase crystals, glass shards, and volcanic rock fragments
altered to zeolites and smectite in tuff of the volcanic rocks.
Clinoptilolite/heulandite, erionite/offlerite, analcime, and
chabazite and rarely phillipsite and mordenite occur with other
authigenic minerals, e.g. Fe- and Mg-rich smectite, Kfeldspar. Gypsum, calcite, dolomite, and hexahydrite were
also found in the some altered tuffs and clay layers. The
zeolite minerals grow up as crypto- to microcrystalline
aggregates after dissolved glass fragments in cavities and
represent most of the matrix in the altered tuffs.
Nine K-feldspar, twelve plagioclase and sixty nine zeolite
minerals were analyzed by microprobe. Zeolite analyses were
made on single crystal and crystal clusters of heulandite,
clinoptilolite, erionite, and chabazite. The structural formulae
of the feldspar were calculated as (Si2.98Al1.03)(K0.67Na0.27Ca0.01)
and (Si2.67Al1.31)(K0.05Na0.60Ca0.28), respectively, and the zeolite
minerals
as
[(Si28.7Al7.3)(Mg1.5Ca0.9Sr0.1)(K1.0Na1.3)],
[(Si29.6Al6.4Fe0.1)(Mg1.0Ca1.0Sr0.1)(K0.8Na0.9)],
[(Si28.3Al8.2)(Mg1.7Ca0.3Sr0.1)(K2.0Na1.2)],
and
(Si9.88Al2.18Fe0.01)(Mg0.2Ca0.6Sr0.03)(K0.3Na0.17)],
respectively.
Clinoptilolites are mostly high-silica Ca-rich heulandites
having intermediate composition between heulandites and
clinoptilolites. Si/Al ratios of heulandites (3.70-4.20) and
clinoptilolites (4.30-5.30) are similar to heulandite group
minerals and their divalent/monovalent cation ratios range
from 0.41 to 5.75 and 0.44 to 3.6, respectively. The structural
(Na+K) content is higher than that of (Ca+Ba+Sr) in all
heulandite group minerals and erionites. Mean Si/Al ratio of
erionites is 3.40 and divalent/monovalent cation ratios are
between 0.42 and 1.25. Zeolite minerals, e.g. analcime,
chabazite, erionite, and phillipsite, and saline minerals such as
gypsum, calcite, dolomite and hexahydrite were precipitated in
a closed alkaline and saline environment. High proportions of
alkali cations would indicate that highly alkaline pH values are
likely in pore water in the tuff.
www.minersoc.org
Goldschmidt Conference Abstracts
636
Acid gases speciation in
H2S-CO2-Portland Cement-H2O
system
J. CENTENO
PDVSA Intevep, Los Teques, Venezuela,
(*correspondence: [email protected])
This study presents the interactions of H2S and CO2 with
the cementitious material used in the oil wells construction to
determine the speciation of these chemicals in a closed system
conditions at high temperatures and pressures. Using a charge
balance was possible to determine the mass of each of the
species involved in the chemical balance of the system and
make the corresponding mass balance. H2S and CO2 are
aggressive agents and their action against the cementitious
material is influenced by the characteristics of cement,
porosity, permeability, type of hydration products, partial
pressure of CO2 and H2S, temperature and composition of
formation water, in particular is important to consider the
salinity. The CO2 attack is preferential on portlandite
[Ca (OH)2] present in cement and its initial impact is minimal
on calcium silicates; deteriorates the outer surface of cement
and migrates through the matrix affecting its internal structure.
Chemical attack of samples was performed in a closed system
under high temperature and pressure (ATAP), with known
concentrations of CO2 and H2S, establishing conditions under
which is progressively increased aggressiveness of the attack
(approximately up to 38 atm CO2 16 atm H2S). Each test series
includes the following time intervals: 20, 40, 80 days. The
mass balance allowed calculating the concentrations of sulfide
(HS-) and bicarbonate (HCO3-), according to the following
expressions:
The main conclusion suggests an inhibitory effect of CO2 on
the solubility of H2S.
Mineralogical Magazine
Lignin decomposition in paddy soils
as affected by redox conditions
C. CERLI1*, Q. LIU2, A. HANKE1, K. KAISER3 AND
K. KALBITZ1
Institute of Biodiversity and Ecosystem Dynamics, Earth
Surface Science, University of Amsterdam, 1098 XH
Amsterdam, The Netherlands (*correspondence:
[email protected]; [email protected], [email protected])
2
Institute of Soil Science, Chinese Academy of Sciences,
210008 Nanjing, China ([email protected])
3
Soil Sciences, Martin Luther University Halle-Wittenberg,
06120 Halle (Saale), Germany
([email protected])
1
In submerged soils, lignin constitutes a major portion of
the total organic matter (OM) because of hampered
degradation under anoxic conditions. Paddy soils management
involves alternating redox cycles with periodic changes in soil
solution chemistry and microbial metabolism. Such an
environment might promote both degradation and preservation
of lignin, affecting the overall composition and reactivity of
total and dissolved OM.
We sampled two soils either subjected to cycles of anoxic
(rice growing period) and oxic (harvest and growth of other
crops) conditions since 700 and 2000 years. We incubated
suspended Ap material, sampled from the two paddy plus two
corresponding non-paddy control soils under oxic and anoxic
condition, for 3 months, interrupted by a short period of three
weeks (from day 21 to day 43) with reversed redox conditions.
At each sampling time (day 2, 21, 42, 63, 84), we determined
lignin-derived phenols (by CuO oxidation) as well as
phospholipids fatty acids contents and composition. We aimed
to highlight changes in lignin decomposition as related to
changes in microbial community composition.
In well-established paddy soils relative short (3 weeks)
changes in redox conditions had no effect on lignin
decomposition or oxidation state. Also, lignin was not altered
during oxic incubation. Since fungi represented only small
portion of the microbial biomass in the studied soils, they were
obviously not capable to cause much degradation, even under
favourable conditions. On the contrary, 3 months of anoxic
conditions resulted in a decrease in lignin-derived phenols.
This decrease was likely not a result of degradation but of
(partial) dissolution and/or pH-induced changes of the surface
properties of Fe and Mn hydrous oxides causing the release of
mineral-associated lignin-derived phenols. Thus, we speculate,
that oxidised lignin fragments produced during the (oxic) dry
period do not remain in the soils but leach with water drainage
during the flooding period.
www.minersoc.org
Goldschmidt Conference Abstracts
Model calculations of scale forming
minerals of high enthalpy geothermal
waters in Turkey
ZIYA CETINER1 AND YONGLIANG XIONG2
Canakkale 18 Mart University, Department of Geological
Engineering, 17010, Canakkale, Turkey
([email protected])
2
1404 North Country Club Circle, Carlsbad, New Mexico,
USA ([email protected])
1
Located on the active Alpine-Himalayan Orogenic Belt,
Turkey’s geological and neo-tectonic evolution had been
dominated with active faults and volcanisms which are the
leading causes of substantial geothermal resources. Such
resources are widespread throughout the country and are
indentified with three distinctive geothermal regions based on
their tectonic settings. Of which, high enthalpy resources,
suitable for geothermal power production, are mainly located
in the western part of the country along the major graben and
associated fault systems. These include Denizli-Kızıldere
(242°C), Aydın-Germencik (232°C), Manisa-Kavaklıdere
(213°C), Aydın-Pamukören (187°C), Canakkale-Tuzla
(175°C), Aydın-Salvatlı (171°C) and Kütahya-Simav (162°C)
[1]. Low and moderate enthalpy sources exist in the Middle
and Eastern Turkey along North Anatolian Fault Zone because
of volcanism and fault formations.
The total geothermal potential in Turkey is estimated to be
about 31,500 MWt. Most of the geothermal development in
Turkey has been initiated by MTA (General Directorate of
Mineral Research and Exploration of) since 1962. A law
allowing geothermal sources discovered by the MTA to be
used by commercial organizations was introduced in 2007.
Moreover, legislation concerning renewable energy was
brought in at the end of 2010. These new laws have led to
increased efforts to explore profitable geothermal electricity
and to use the heat directly.
In this study, geochemistry of the medium to high
enthalpy geothermal waters suitable for electrical energy
production has been critically reviewed and the solubilities of
potential scale-forming minerals including silica polymorphs
and carbonates at various temperatures have been calculated
by using EQ3/6, for determining the optimum operation
conditions in power generation.
[1] Mertoglu O. et al. (2010). Proceedings World Geothermal
Congress. Bali, Indonesia, 25-29 April 2010.
Mineralogical Magazine
637
Geochemical tracing of water-rock
interactions in the Ringelbach
granitic research catchment
(Vosges, France)
F. CHABAUX , T. SCHAFFHAUSER, B. FRITZ,
B. AMBROISE AND P. STILLE
LHYGES, Université de Strasbourg/EOST, CNRS, France
([email protected])
For constraining the nature of water-rock interactions
occuring within granitic watersheds a geochemical and
isotopic (Sr, U) study of all springs within the Ringelbach
granitic research catchment (Vosges, France) has been
undertaken, following the approach classically developped in
the Lab [1]. This study also includes the analysis of water
samples collected in two 150-m deep boreholes, which permit
the evaluation of (a) water flux and composition in the deeper
part of the watershed and (b) deep weathering processes
within the granitic bedrock. At the scale of a single spring,
important geochemical variations are observed over the year.
Such variations cannot be accounted for by a simple mixing
scenario of rainwater contributing in variable quantities to the
chemical composition of these waters. For each considered
spring, the geochemical variations have to be interpreted as
the contribution of two different weathering fluxes with
changing intensities over the hydrological cycle. At the scale
of a same slope a systematic geochemical variation of the
spring waters is observed according to their emercgence
altitude along this slope. These chemical changes affect both
the elementary and U activity ratios but not the Sr isotope
ratios. This indicates that geochemical variations are not
simply controlled by mixing processes between waters having
interacted with different lithologies. Furthermore, geochemical
variations observed in subsuface waters (springs) cannot be
explained by a contribution of deep waters (boreholes). All
together these data suggest that the main parameter explaining
geochemical variations of water samples collected within the
Ringelbach catchment is the water pathway of the waters
within the watershed. Modeling approaches confirm and
constrain the importance of this parameter in the control of
geochemical characteristics of surface waters (Schaffhauser et
al., this issue).
[1] S. Durand, F. Chabaux, S. Rihs, P, Duringer, P. Elsass
(2005), Chem. Geol., 220, 1-19; [2] M.L. Bagard, F. Chabaux,
Oleg S. Pokrovsky, J. Viers, Anatoly S. Prokushkin, P. Stille,
S. Rihs, A.D. Schmitt, B. Dupré (2011) GCA, DOI:
10.1016/j.gca.2011.03.04.
www.minersoc.org
638
Goldschmidt Conference Abstracts
Biogeochemical characterization of
Mercury (Hg)-contaminated
sediments at the Bunikasih Gold
mine, West Java Province, Indonesia
Interactions of Eu(III) and Cm(III)
with celestite and strontianite:
Precipitation kinetics and uptake
mechanisms characterisation
SITI KHODIJAH CHAERUN1,2*, SAKINAH HASNI1,
EDY SANWANI3 AND D. BARRIE JOHNSON4
Laboratory of Mining Biotechnology and Enironmental
Bioengineering, School of Lifesciences and Technology,
Institut Teknologi Bandung, Ganesha 10, Bandung 40132,
West Java, Indonesia (*correspondence:
[email protected])
2
Centre for Life Sciences, Institut Teknologi Bandung
3
Department of Metallurgical Engineering, Faculty of Mining
and Petroleum Engineering, Institut Teknologi Bandung
4
School of Biological Sciences, Bangor University, UK
1
The objective of this study was to investigate the
biogeochemical characteristics of mercury (Hg)-contaminated
sediments at the Bunikasih Gold Mine, West Java Province,
Indonesia in order to provide a basic and initial description of
biogeochemically sediments at this contaminated site for
bioremediation purposes. Sediments contained elevated total
Hg concentrations of 28 – 61 ppm. XRD analysis revealed the
presence of quartz and berlinite minerals, indicating that
mercury contained in sediments was not in mineral form of
mercury but in other form. SEM-EDS analysis indicated the
presence of Si (30 – 44%), Al (0.6 – 8%), O (45 – 51%), and
C (3.5 – 7%). Ten heterotrophic bacteria that were resistant to
HgCl2 (25 ~ 550 ppm) were isolated from the Hgcontaminated sediments. 16S rRNA gene sequence analysis
identified the bacteria as strains of Pseudomonas koreensis,
Pseudomonas putida, Pseudomonas fulva, Stenotrophomonas
maltophilia and Aeromonas sobria.
The findings of this study provide evidence of
heterotrophic bacteria associated with Hg-contaminated
sediments as well as provide the first information of
phylogenetically-diverse Hg-resistant bacteria in the Hgpolluted sites of Indonesia. Such information may prove
highly useful for developing in situ bioremediation of Hgcontaminated sites in Indonesia.
This work was supported by a grant from HIBAH DIKTI
DIPAH ITB 2010, Indonesia
Mineralogical Magazine
A. CHAGNEAU1,2, K. HOLLIDAY1, M. SCHMIDT1,
T. STUMPF1 AND T. SCHÄFER1,2
Karlsruhe Institute of Technology (KIT), Institute for Nuclear
Waste Disposal (INE), D-76344 EggensteinLeopoldshafen, Karlsruhe, Germany
2
Freie Universität Berlin, Institute of Geological Sciences,
Hydrogeology Group, 12249 Berlin, Germany
1
The present work focuses on the characterization of
lanthanides and actinides interactions with celestite (SrSO4)
and strontianite (SrCO3). Precipitation kinetics studies of the
minerals were performed in batch type and mixed-flow
reactors experiments, in presence and absence of Eu(III) and
Cm(III) in solution. It is shown that the presence of Eu(III)
and Cm(III) as trace elements (up to 4.5*10-4 mol L-1) have no
effect on the precipitation rates, which are dependant on the
initial saturation index.
TRLFS analyses shown a clear incorporation of the Eu(III)
and Cm(III) into the mineral structures, with a minor surface
component for the strontium sulfate. Similar studies were
earlier performed on aragonite, calcite (CaCO3) and gypsum
(CaSO4) in the same experimental conditions. Incorporation
was observed for aragonite and only surface complexation for
the calcium sulfate, while both mechanisms were observed for
calcite. Therefore, the ligand strength was expected to play an
important role in the uptake mechanisms. The present work
focused on two minerals isostructural with aragonite,
demonstrating the importance of the lattice parameters in the
uptake mechanisms as well. Moreover, the presence of Eu(III)
and Cm(III) as incorporated species has no effect on these
lattice parameters.
The Eu(III) and Cm(III) affinity coefficients for the SrSO4
and SrCO3 structure as well as the strontianite and celestite
precipitation rates as a function of the oversaturation (SI) were
determined. This information is prerequisite to develop a
reactive transport model able to predict the behavior of these
elements in a porous media under chemical perturbation.
www.minersoc.org
Goldschmidt Conference Abstracts
Enhanced growth of Acidovorax
delafieldii 2AN during nitratedependent Fe(II) oxidation in
continuous-flow systems
A. CHAKRABORTY1, J. SCHIEBER2, E.E. RODEN3 AND
F.W. PICARDAL1*
School of Public and Environmental Affairs, Indiana
University, Bloomington, IN 47405 USA
(*correspondence: [email protected])
2
Department of Geological Sciences, Indiana University,
Bloomington, IN 47405 USA
3
Department of Geology and Geophysics, University of
Wisconsin, Madison, WI 53706 USA
1
It is not clear if microbial, NO3- -dependent, Fe(II)
oxidation (NDFO) is energetically beneficial to cells or if it is
primarily a fortuitous, side-reaction, involving both abiotic
and enzymatic reactions during heterotrophic growth.
Although recent batch experiments by others have suggested
that NDFO may provide an energetic benefit through a
mixotrophic physiology, it is not known if long-term growth
yields can be enhanced by Fe(II) oxidation, and if this
enhancement can be realized at environmentally relevant Fe2+,
NO3-, and organic C concentrations. Acidovorax delafieldii
2AN was incubated anoxically in batch reactors using a
bicarbonate-buffered,
artificial
groundwater
medium
containing 5-6 mM nitrate, 8-9 mM Fe(II) and 1.5 mM
acetate. A novel, continuous-flow culture system was also
used to evaluate growth on low concentrations of substrates,
e.g. 100 !M nitrate, 20 !M acetate and 50-250 !M Fe(II).
In batch reactors, almost 90% of the Fe(II) was oxidized
with concomitant reduction of NO3- and complete
consumption of acetate. However, cells became encrusted with
Fe(III) (oxy)-hydroxides, lost motility and formed aggregates.
Encrusted cells could neither oxidize more Fe(II) nor utilize
further additions of acetate. In batch experiments using
chelated iron [Fe(II)-EDTA], aggregated and encrusted cells
were not produced and further additions of acetate and Fe(II)
could be oxidized. This suggests that the cell encrustations
prevent substrate entry into the cell or otherwise render cells
physiologically inactive. In the continuous-flow system, the
growth yield of A. delafieldii 2AN was always greater in the
presence of Fe(II) than in its absence and ESEM examination
showed that encrustation was minimized. This suggests that
cell encrustations may be an artifact of the high concentrations
of Fe(II) and NO3- used in batch cultures. Our results provide
evidence that, under environmentally relevant concentrations
of Fe(II) and NO3- , NDFO can enhance growth without the
formation of cell encrustations that may limit viability in batch
culture.
Mineralogical Magazine
639
Kimberlites, flood basalts and mantle
plumes: New insights from the
Deccan Large Igneous Province
N.V. CHALAPATHI RAO1,2* AND B. LEHMANN2
Centre of Advanced Study in Geology, Banaras Hindu
University, Varanasi-221005, India
(*correspondence: [email protected])
2
Mineral Resources, Technical University of Clausthal,
Adolph-Römer-Straße 2A, 38678 Clausthal-Zellerfeld,
Germany ([email protected])
1
A temporal and spatial relationship between smallvolume, volatile-rich and highly potassic continental melt
fractions, such as kimberlites and related rocks, and largevolume continental flood basalts exists in several Large
Igneous Provinces (LIPs). Many of these LIPs are also widely
regarded as products of mantle plume-lithosphere interactions.
The small-volume melts either immediately pre-date or postdate or even are co-eval with the main flood basalt event. The
overlap of ages between the flood basalts and the kimberlites
very likely reflects a cause and effect relationship via mantle
plumes.
Recently discovered end-Cretaceous diamondiferous
kimberlites (orangeites) in the Bastar craton of central India
which are synchronous with the flood basalts, carbonatites,
lamprophyres and alkaline rocks of the Deccan LIP provide an
opportunity to re-evaluate the role of mantle plumelithosphere interactions in the generation of these disparate
magmas. The geographical zonation of the kimberlitelamprophyre-carbonatite-alkaline rock spectrum in the Deccan
LIP is inferred to reflect variable thickness of the pre-Deccan
Indian lithosphere with a thinner lithosphere along the known
rift zones of northwestern and western India and a thickened
lithosphere underlying the Bastar craton of central India. This
heterogeneity is thought to have controlled the volume of melt
generation and melt ascent, as well as the ultimate alkaline
magma type.
These findings are supported by the regional lithospheric
thickness map, generated from converting seismic shear wave
velocities into temperature profiles, which depicts that the
present-day lithosphere beneath the Bastar craton is thicker
than that in western and NW India where the centre of the
Deccan plume-head was located. Thermal weakening of the
sub-Bastar craton due to mantle plume-lithosphere interaction
at the end-Cretaceous resulting in a thin-spot is suggested to
have controlled the Deccan-related mafic dyke emplacement
in the Bastar craton
www.minersoc.org
640
Goldschmidt Conference Abstracts
A new Gallionellales isolate: A model
system for comparative studies of
Fe-oxidizer physiology and
biomineralization
CLARA S. CHAN*, SEAN T. KREPSKI AND GAURAV SAINI
Dept. of Geological Sciences, University of Delaware,
Newark, DE 19716 (*correspondence: [email protected])
The Fe-depositing bacterium Gallionella ferruginea was
first described in the early 19th century based in part on its
twisted ribbon-like stalk, which has since been widely used in
its identification. In 1993, Hallbeck et al. [1] reported the 16S
rRNA sequence of a stalk-forming isolate. Recently,
researchers have isolated several Fe-oxidizing bacteria (FeOB)
related to Gallionella; however, none produce biomineral
structures that typically comprise Fe microbial mats, so we
have made relatively little progress characterizing and linking
FeOB physiology, biomineralization, and mat formation.
Towards these goals, we have isolated a novel stalk-forming
FeOB, strain R-1, from a freshwater Fe seep in Delaware,
USA. R-1 is a neutrophilic, obligate Fe-oxidizing
Betaproteobacterium. Despite strong morphological similarity
to G. ferruginea [1], this isolate shares only 93.6% 16S rRNA
gene sequence similarity. It is more similar (94.0-94.4%) to
Sideroxydans isolates [2,3], which do not produce
morphologically-distinct minerals. Its phylogenetic distance
from other Gallionellales, especially its distance from G.
ferruginea shows the high diversity of FeOB in this order.
R-1 is remarkably similar to the marine Zetaproteobacterial Fe-oxidizer Mariprofundus ferrooxydans PV-1,
presenting an opportunity for comparative study. Both
organisms are obligate FeOB isolated from Fe mats. R-1
oxidizes ~1-2x10-14 mol Fe/cell, comparable to PV-1
(0.9x10-14 mol Fe/cell). Like PV-1, R-1 cells are relatively Fefree, with a fibrillar, ribbon-like Fe and polysaccharide-rich
stalk, binding multiple lectins. We postulate that the R-1 stalk
plays similar roles to that of PV-1, especially as a mechanism
for removing Fe(III) waste from the cell [4]. TEM studies
have shown that cell surface structure differs from PV-1,
which may imply different surface chemistry. We have been
investigating surface characteristics by atomic force
microscopy, electrophoretic mobility, hydrophobicity tests,
and probing by charged nanoparticles. Results to date suggest
that both R-1 and PV-1 surfaces have near-neutral charge,
which helps explain how cells avoid encrustation.
Evaluation of relationships used to
model sea surface iodide
concentrations
R.J. CHANCE1*, A.R. BAKER1, L.J. CARPENTER2
1
AND T. JICKELLS
School of Environmental Sciences, University of East Anglia,
UK (*correspondence: [email protected])
2
Department of Chemistry, University of York, YO10 5DD,
UK
1
Sea-to-air exchange supplies reactive iodine to the
atmosphere, where it contributes to tropospheric ozone
depletion and particle formation, and allows the dispersal of
radioactive iodine discharges. A major contributor to this
process is the reaction of ozone with iodide at the air-sea
interface. Sea surface iodide concentrations range from 5 to
200 nM, varying with latitude and proximity to the coast; the
controls on this distribution are not well understood. Recent
attempts to quantify the contribution of the ozone–iodide
reaction to large scale ozone deposition [1,2] have modelled
sea surface iodide concentrations using observed relationships
between iodide and nitrate [3] or chlorophyll [4].
Here, we present new iodide measurements from the
tropical eastern Atlantic and the Southern Ocean, incorporate
these into a preliminary global surface iodide climatology and
use this to evaluate the two different modelling approaches.
We find that neither model was able to fully explain the
observed global iodide distribution. We propose the
compilation of a global iodide climatology which can be used
to rigorously test models and new hypotheses concerning the
marine biogeochemical cycle of iodine. If spatial resolution is
sufficient, such a database might also be used directly in
modelling studies.
[1] Ganzeveld et al. (2009), Glob. Biogeochem. Cyc. 23,
GB4021. [2] Oh et al. (2008), Atmos. Environ. 42, 4453-4466.
[3] Campos, Sanders & Jickells (1999), Mar. Chem. 65, 167175. [4] Rebello, Herms & Wagener (1990), Mar. Chem. 29,
77-93.
[1] Hallbeck et al. (1993) J. Gen. Microbiol. 139: 1531-5. [2]
Emerson and Moyer (1997) Appl. Env. Microbiol. 63: 478492. [3] Lüdecke et al. (2010) Env. Microbiol. 12: 2814-25. [4]
Chan et al. (2011) ISME J. 5:717-27.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Carcass Island: A new site for the
observation of Southern South
American dust in the western
Falkland Islands
R.J. CHANCE AND A.R. BAKER*
School of Environmental Sciences, University of East Anglia,
UK (*correspondence: [email protected])
Dust originating in Southern South America (SSA) is
probably the largest source of mineral matter and its
associated trace elements to the remote South Atlantic and
Atlantic sector of the Southern Ocean. Antarctic ice core
records show very large variations in dust supply over glacial
– interglacial timescales, which may be related to changes in
atmospheric pCO2 and temperature proxies.
Our understanding of the current strength and transport of
SSA dust sources is very poor however, partly because
persistent cloud cover makes remote sensing observations in
the region difficult, but also due to a lack of observations of
surface level dust concentrations along transport pathways.
In September 2010 we established a new site for the
collection of SSA dust on Carcass Island (51°15’S, 60°35’W)
in the western Falkland Islands, as part of the UK contribution
to the GEOTRACES programme. Weekly aerosol samples
were collected at the site between September 2010 and April
2011, using a high-volume sampler under the control of a
wind sector monitor (“clean” sector 220-310 degrees, relative
to true north). The collector was mounted at the top of a short
(~3m) aluminium scaffolding tower near the crest of a small
ridge approximately 400m from the shore. The nearest
settlement is >3km downwind of the site. During site visits
rain samples were also collected either at the aerosol site or
settlement.
Samples will be analysed for their soluble and total trace
metal content and major ions (including macronutrient)
chemistry. We intend to operate the site in future years.
This contribution will describe the Carcass Island site in
detail and we hope to be able to present preliminary results
from the first year of sampling.
Mineralogical Magazine
641
High-pressure Mössbauer
Spectroscopic study of Lohawat
(Howardite) meteorite up to 9GPa
USHA CHANDRA1, POOJA SHARMA1 AND
G.PARTHASARATHY2
High Pressure Physics Lab., Department of Physics,
University of Rajasthan,Jaipur 302055 ;
([email protected])
2
National GeoPhysical Research Institute(CSIR), Uppal Road,
Hyderabad 500606 ([email protected])
1
The effect of high-pressure on Lohawat( Howardite)
Meteorite which fell at Lohawat village in Jodhpur was
studied using Mössbauer spectroscopic technique with
diamond anvil cell and 4:1 methanol:ethanol mixture as
hydrostatic pressure medium[1]. The main minerals detected
in the meteorite were orthopyroxenes and plagioclase with
little amount of olivine. Ambient Mössbauer study showed
ferrosilite with Fe2+ in two inequivalent octahedral sites M1
and M2 [2]. Both the sites behave differently under
pressure.At 2.8 GPa, a sudden decrease in Mössbauer
parameters (quadrupole splitting and isomer shift) indicate
transformation of high spin Fe2+ to low spin configuration.
The trend of decrement continues up to 5.6 GPa where isomer
shift reaches a low of -0.14 mm/s . Further increase in pressure
reverses the trend and at 8.4 GPa the value becomes
+0.05mm/s. The observation of low spin Fe2+ configuration in
pyroxene is unusual , not observed in terrestrial samples. Such
a behaviour resembles post-peovskite character which occurs
at ~ 120 GPa [3]. The presence of low spin Fe2+ phase at low
pressure of ~ 2GPa indicates the defects generated in the
system under shock impact. The results thus obtained are also
supported by high pressure electrical resistivity measurements.
We acknowledge CSIR, New Delhi; PLANEX (ISRO),
Ahmedabad for Financial support and Prof. R.P.Tripathi for
providing the meteorite sample.
[1] Chandra U., Ind. J. (2007) Pure & Appl. Phys..45 790.
[2] Tripathi R.P. et al. (2000) Meter. & Planet. Sc. 35 201.
[3] McCammon et al. (2010) PEPI 180 215.
www.minersoc.org
642
Goldschmidt Conference Abstracts
Phosphorus in olivine from Italian
potassium-rich lavas
High-precision age for the
Haifanggou Formation and its
implications for the coevolution of
plants and atmospheric CO2
S.R. CHANEVA*, I.K. NIKOGOSIAN, M.J. VAN BERGEN
AND P.R.D. MASON
Department of Earth Sciences, Utrecht University, the
Netherlands
(*correspondence: [email protected];
[email protected]; [email protected]; [email protected])
Phosphorus in igneous olivine is promising as a
petrogenetic proxy and as a sensitive indicator of crystal
growth histories [1,2]. To explore its applicability in solving
outstanding issues concerning Italian K-rich magmatism, we
analyzed a collection of well characterized forsterite-rich
olivines, along with their Mg-rich melt inclusions (MI) for P
contents. The wide compositional range of the basaltic
samples (from high to low-K) and the regional coverage of
volcanic centres (between the Roman Province and Vulture)
enabled us to detect variations in magmagenetic conditions
that control the behaviour of phosphorus.
Phosphorus concentrations in the olivines were determined
by EPMA (15kV, 100nA, extended counting times) and by
LA-ICPMS, along with standard major and trace element
analyses that included homogenized MI. Intra-crystal
variations were explored in rim-to-rim traverses by EPMA,
following a procedure optimized for P. Detection limits were
40±20 ppm for both techniques, based on the analyses of a
series of reference materials. The measured olivines cover an
overall range in P between 40 and 230 ppm, despite their
consistent forsterite-rich nature (Fo>87). The olivines from the
medium to low-K series (M-LKS) contain less P (<70 ppm,
except for Campi Flegrei where <230ppm was found) than
those from the high-K series (HKS) which reach a maximum
of 130 ppm. Corresponding MI from M-LKS and HKS
samples contain up to 0.7 and 1.9 wt.% P2O5, respectively.
The P contents in olivine tend to increase with K2O and
P2O5 contents in the melt, and show regional systematics,
suggesting that they signal variations in mantle source
composition and/or mode of melt extraction. On the other
hand, some M-LKS melts with similar P contents crystallized
olivines with significantly different contents, indicating that P
in the melt may not be the only control of uptake by olivines.
Additional factors to be considered include growth rate [1] and
coupled substitutions (e.g., with Al, Cr, Ti). Also, profiles in
selected olivines show P depleted zones around MI, which
questions the supposed immobility of P in olivine.
[1] Brunet & Chazot (2001) Chem. Geol. 176, 51-72.
[2] Milman-Barris et al. (2008) CMP, 155, 739-765
Mineralogical Magazine
SU-CHIN CHANG*1, HAICHUN ZHANG2,
SIDNEY R. HEMMING3,4, GARY T. MESKO3
2
AND YAN FANG
Dept. of Earth Sciences, The University of Hong Kong, Hong
Kong (*correspondence: [email protected])
2
State Key Laboratory of Palaeobiology and Stratigraphy,
Nanjing Institute of Geology and Palaeontology, Chinese
Academy of Sciences, Nanjing, China
3
LDEO, Columbia University, NY, USA
4
Dept. of Earth & Environmental Sciences, Columbia
University, NY, USA
1
Atmospheric CO2 levels have fluctuated greatly during the
Phanerozoic [1]. Although many organic and inorganic
factors affected atmospheric CO2 levels, plants have played an
important role in CO2 fluctuations. Recently, most
paleobotanists accept an Early Cretaceous origin for
angiosperms and support that angiosperms underwent a rapid
ecological radiation in middle-late Cretaceous [2]. Because
high concentrations of Cretaceous atmospheric CO2 underwent
a long-term decline, several hypotheses suggested that the
origin and radiation of angiosperms and atmospheric CO2
levels are closely related [3].
The recent discovery of Schmeissneria from the middle
part of the Jurassic Haifanggou Formation provided evidence
that the origin of angiosperms could predate the Early
Cretaceous [4]. Because previously reported ages for the
Haifanggou Formation are scattered and the uncertainties of
these ages were fairly large, our on-going work aims to
establish high-precision 40Ar/39Ar ages for volcanic ashes from
the Haifanggou Formation.
Our preliminary results indicate that Schmeissneria is
older than 160 Ma. The age results will provide a robust
geochronological calibration for the oldest angiosperm and
will improve our knowledge of the link between atmospheric
CO2 and the rise and the radiation of angiosperms.
[1] Berner et al. (2001) American Journal of Science 301,
182-204. [2] Friis et al. (2005) Current Opinion in Plant
Biology 8, 5-12. [3] Beerling (1994) Philosophical
Transactions of the Royal Society, London B346, 421-432. [4]
Wang et al. (2006) Progess in Natural Science 16, 222-230.
www.minersoc.org
Goldschmidt Conference Abstracts
Characteristic elements and lead
isotope of Kaempferia Galangal from
Yangchun, Guangdong, China
Weathering fluxes from time series
sampling of the Irrawaddy and
Salween Rivers
X.Y. CHANG1,2, S.M. FU1, N. CHEN1, H. LIU1,
H.Y. ZHANG1, Q.H. WU1, X.F. ZHAO1 AND B.Q. ZHU2
School of Environmental Science and Engineering,
Guangzhou University, Guangzhou 510006, Guangdong
China; (*correspondence: [email protected])
2
Guangzhou Institute of Geochemistry, Chinese Academy of
Science, Guangzhou 510640, Guangdong China;
1
Products of designations of origin was used to describe a
product originating in that specific place, region, or country, if
the quality or characteristics of which were essentially or
exclusively due to a particular elements geochemical factors,
and the production, processing and preparation of which took
place in the defined specific place, region, or country [1-3].
Select products of designations of origin Kaempferia
Galangal from YangChun, Guangdong Province, China. The
plants and soil profile samples were collected and the element
content, element speciation, and lead isotope ratio were
determined. Through the multivariate statistical analysis to
ascertain the characteristic elements and multielement group,
and provide evidence for establishing the elements- isotope
fingerprints of product identification system. Fourteen trace
elements in soil and galangal samples were measured to
explore the feasibility of characteristic elements as the
fingerprinting marker of products of origin. The results
showed that there was a significant correlation between the
contents of trace elements in soil and galangal. Trace elements
yield a good inheritance between soil and galangal. Mg, Mn,
Zn, Sb, Fe, Cu and Sr were the characteristic elements of
Galangal by weight analysis. The geochemical tracer method
could be used in research the effect of regional geochemical
background on the products of origin.
Lead isotope ratios analysis result showed that the sources
of lead in the soil profile and Galangal was very stable, lead
isotope ratios of Galangal was very close to the distribution
characteristics of soil region. 206Pb/208Pb -206Pb/207Pb showed
significant correlation further proves the product with soil
were homology. Lead isotope could be used as the criterion of
fingerprint identification of products of designations of origin.
[1] Rosman et al. (1998) Environmental Research 78, 161167. [2] Paul & Trevor (2007) Geology 28, 627-630. [3]
Chang et al. (2011) Chinese Journal of Geochemistry 30, 138144.
The project was supported by NSFC(40772201).
Mineralogical Magazine
643
HAZEL CHAPMAN1*, MIKE BICKLE 1, SAN HLA THAW2
2
AND HRIN NEI THIAM
Earth Sciences, University of Cambridge, Downing St.
Cambridge CB2 3EQ, UK (*[email protected])
2
Department of Meteorology & Hydrology, 50 Kaba-Aye
Pogoda Rd, Mayangon 11061, Yangon, Myanmar
1
The Irrawaddy and Salween rivers in Myanmar Burma
have water fluxes ~70% of the Ganges-Brahmaputra river
system. Together these systems are thought to deliver about
half the dissolved load from the tectonically active
Himalayan-Tibetan orogen [1]. Previously very little data was
available on the dissolved load and isotopic compositions of
these rivers.
Here we present time series data of 171 samples collected
fortnightly at intervals throughout 2005 to 2007 from the
Irrawaddy and Salween at locations near the river mouths, the
Irrawaddy at Myitkyina, the Chindwin, a major tributary of
the Irrawaddy and a set of 28 small tributaries which rise in
the flood plain of the Irrawaddy between Yangon and
Mandalay. The samples have been analysed for major cation,
anion, Sr and 87Sr/86Sr ratios. The new data indicates that the
Irrawaddy has an average Na concentration only a third of the
widely quoted single published analysis [2].
The catchment of the Salween extends across the Shan
Plateau in Myanmar through the Eastern syntaxis of the
Himalayas and into Tibet. The Irrawaddy flows over the
Cretaceous and Tertiary magmatic and metamorphic rocks
exposed along the western margin of the Shan Plateau and the
Cretaceous to Neogene Indo-Burma ranges. The chemistry of
the waters reflects these differences with the 87Sr/86Sr
compositions of the Salween and Upper Irrawaddy (between
0.713 and 0.718) significantly higher than the downstream
Irrawaddy (0.709 to 0.711) and the Chindwin (0.708 to 0.710).
The Irrawaddy and the Chindwin exhibit lower 87Sr/86Sr and
Na/Ca ratios during and immediately post-monsoon,
interpreted to reflect higher weathering of carbonate at high
flow (c.f. [3]). The Salween exhibits higher 87Sr/86Sr ratios but
lower Na/Ca ratios during the monsoon, interpreted to reflect
higher inputs from the upper parts of the catchment in the
Himalayas.
[1] Robinson et al., (2007) Journal of Geology 115, 629–640.
[2] Meybeck & Ragu, (1997), UNEP (United Nations
Environment Programme) GEMS, 245 pp. [3] Tipper et al.,
(2006) Geochim. Cosmochim. Acta. 70, 2737–2754.
www.minersoc.org
644
Goldschmidt Conference Abstracts
Complexation studies of EDTA with
99
Tc analogue rhenium
PAUL M. CHAPMAN, CLAIRE L. CORKHILL AND MARÍA
ROMERO-GONZÁLEZ
Cell-Mineral Research Centre, Kroto Research Institute, The
University of Sheffield, S3 7HQ, UK
(*correspondence: [email protected])
Technetium-99 (99Tc) is one of the important waste
products formed during the nuclear fuel cycle. In oxidising
conditions, 99Tc exists as the highly mobile pertechnetate
anion (Tc(VII)O4-), which has widespread environmental
implications. When present in anoxic environments and in the
presence of reducing species, it is expected that an insoluble
solid oxide, Tc(IV)O2, will form. Complexation of Tc(IV)
with man-made and naturally occurring ligands is expected to
increase environmental mobility.
The purpose of this investigation was to use a novel
technique, Raman spectroscopy, to determine the
complexation of rhenium, a non-radioactive analogue for 99Tc,
with ethylenediaminetetraacetic acid (EDTA) under oxic and
anoxic conditions. EDTA is a common nuclear waste cocontaminant and has functional groups representative of much
larger natural organic molecules.
In oxic and anoxic conditions, perrhenate (Re(VII)O4-) and
EDTA were combined with HCl to attain pH values of 3.7, 6.5
and 10.3. Raman spectroscopy showed that the EDTA and
perrhenate remained unchanged (e.g. 971cm-1 peak
characteristic of the Re-O bond in a perrhenate anion was
observed) at all pH values, indicating that no complexation
had occurred.
Under highly acidic (pH 0.6) and anoxic conditions, in situ
reduction of Re(VII) in the presence of EDTA resulted in an
orange-yellow colour solution and a UV-VIS peak at 450nm,
indicative of the formation of a Re(IV)-complex. Changes in
the Raman spectrum of this solution also indicated
complexation shifts of a CN stretch (to 1112cm-1) and a COOvibration (to 1332cm-1). Other Raman bands of the Re-EDTA
complexes were also investigated for complexation shifts and
binding mode information.
It has been shown that rhenium complexes to EDTA by in
situ ligand reduction under very low pH conditions. Binding
through the carboxylate and nitrogen groups of a tetradentate
EDTA ligand to a mono-oxorhenium core is proposed. It is
hypothesised that 99Tc could complex under less harsh
conditions in presence of ligands, which would prevent the
formation of the precipitate Tc(IV)O2 and hence increase the
environmental mobility of 99Tc.
Mineralogical Magazine
H2-rich fluids issued from the Kulo
Lasi volcano, a new active
hydrothermal field recently
discovered in the South-West Pacific
J.L. CHARLOU*, J.P. DONVAL, C. KONN, V. GUYADER,
Y. FOUQUET AND THE SCIENTIFIC PARTIES
Ifremer c/Brest, Laboratoire de Géochimie et Métallogénie,
BP70, 29280, Plouzané
(*correspondance: [email protected])
A lot of Back-arc basins (Fidji, Lau, Manus,…)
investigated in the last 20 years revealed an intense
hydrothermal activity. A new active vent field was recently
discovered off-shore the Futuna island in an unexplored area
during a French cruise (September 2010) from hydrothermal
anomalies detected in the seawater column. High-temperature
fluids were collected by the submersible Nautile from active
vents located on a volcano (Kulo Lasi caldeira). The fluids
exhibit temperatures of 343°C, pH of 2.36, low H2S content
(1-3 mM), variability in chlorinity (485 to 735 mM) and are
enriched in Mg and SO4. Mixing lines of elements vs Mg
clearly reveal three types of fluids, all controlled by phase
separation. Mg and SO4 data in fluids also show a magmatic
influence. Silica measurements show that the reaction zone is
at a relatively low depth (~700 m). The fluids are poor in H2S
and CH4 but enriched in CO2 and H2 and also contain a lot of
organic compounds (see Konn et al., this meeting). The
enrichment in CO2 is explained by magmatic degassing from
arc-magmas very rich in CO2 compared to ridge-magmas, as
previously shown in many active sites in back-arc basins. The
generation of H2 is explained by cristallization of the
ascending magmatic basalt and by interaction of hot lava with
seawater possible during the hydrothermal circulation. The
Kulo Lasi fluids are compared to other fluids previously
studied in various back-arc basins.
www.minersoc.org
Goldschmidt Conference Abstracts
Oxygen dynamic in the Eastern South
Pacific OMZ
JOSE CHARPENTIER1* AND OSCAR PIZARRO2
Oceanographic center for the Eastern-South Pacific, COPAS,
University of Concepción, Casilla 160-C, Concepcion,
Chile (*correspondence: [email protected])
2
Department of Geophysics, Faculty of Physical and
Mathematical Sciences, University of Concepción, Casilla
160-C, Concepcion, Chile ([email protected])
What real constraints do cherts bring
on precambrian surface
temperatures?
MARC CHAUSSIDON1 , PHILIPPE LACH2,
FRANCOIS ROBERT3, MARIE CHRISTINE BOIRON3 AND
BEATRICE LUAIS1
1
The eastern South Pacific holds one of the largest and
most intense oxygen minimum zones (OMZ) of the world.
This region also sustains a very high productivity and a unique
ecosystem constrained by low oxygen concentration. To
analyze the temporal evolution of the OMZ and relevant
processes related to its biogeochemistry a monthly, shipbased, oceanographic time series have been maintained over
the continental shelf off central Chile (~36.5º S) since 2002
[1]. During the last 2 years moored instruments have been
added to this initiative including an ADCP to measure currents
in the water column, and sensors of temperature and oxygen.
Additionally several oceanic glider sections have been carried
out along the same region.
Dissolved oxygen over the continental shelf is very low
(typically lees than 0.5 mL L-1) immediately below the mixing
layer. Its temporal variability shows a marked seasonal
pattern, mainly driven by upwelling events that predominate
during austral spring-summer. The mechanism by which
upwelling drives mid-water anoxia is not well known, but is
greatly related to the supply of fresh nutrients to the photic
zone, and to the advection of low-oxygen water from the
north. Winter oxygen concentrations are usually larger in the
water column and are related to downwelling events and to the
increasing of fresh water discharge. These phenomena related
to the dissolved oxygen variability off central Chile are
discussed in this work based on observational evidences.
aDta from moored instruments shows an interesting
pattern that suggests upwelling (and downwelling) events
affect oxygen concentration in “pulses” that occur in a
temporal scale of days. Oxygen budget for the upper and
lower layer of the water column shows that biological oxygen
production in the mixed layer during spring-summer is almost
equilibrated by biological oxygen consumption. Preliminary
modeling results of the oxygen dynamics are also discussed.
[1] Ulloa, O. and S. Pantoja (2009) Deep Sea Research Part
II: 56 987-991 [2] Paulmier, A., D. Ruiz-Pino, V. Garçon, and
L. Farías (2006) Geophysical Research Letters 33 L20601,
doi:10.1029/2006GL026801
Mineralogical Magazine
645
CRPG-CNRS, Nancy Université, BP 20, 54501 Vandoeuvrelès-Nancy, France
(*correspondence: [email protected]).
2
LMCM-CNRS-MNHN, 61 rue Buffon, 75231 Paris Cedex 5,
France. .
3
G2R-CNRS, Nancy Université, Boulevard des Aiguillettes,
B.P. 70239, 54506 Vandoeuvre-lès-Nancy, France
1
The extent of surface temperature change during the
Precambrian is one of the key questions for the evolution of
the Earth and the development of life. Solar physics dictates
that the luminosity of the Sun was 25-30‰ lower than today
in the early archean [1, 2]. Archean surface temperatures
above the freezing point of water, as indicated by marine
sediments of that age, were likely the result of enhanced
concentration of greenhouse gases and/or decrease in Earth
albedo or both [3, 4]. The low #18O values discovered in
archean cherts of presumably marine sedimentary origin can
be interpreted as reflecting very high surface temperatures 5585°C during this period [5 and refs therein]. Contradictory
lower temperatures have been infered from cherts and from
thermodynamic stability fields of other minerals [6, 4]. Studies
of Si isotopic compositions of cherts [7] and of micrometer
scale distribution of #18O and #30Si values [8] allow to add
independant constraints on seawater temperature and to define
quantitative criteria to assess the origin of cherts (sedimentary
or not) and the preservation of their isotopic signature. In
addition it allows to propose a way to correct the inferred
seawater temperature from isotopic fractionation taking place
during the formation of chert upon diagenesis. Germanium
concentrations (the partitioning of Ge between quartz and
fluid is temperature dependant) in precambrian cherts show a
range from ' 0.1 to '10 ppm (this study) which adds
potentially another dimension to constrain the silica cycle and
seawater temperatures in the precambrian.
[1] Gough D. O. (1981) Sol. Phys. 74, 21-34. [2] Minton D. A.
and Malhotra R. (2007) Ap. J. 660, 1700-1706. [3] Kasting J.
F. (1993) Science 259, 920-926. [4] Rosing M. T. et al. 2010)
Nature 464, 744-747. [5] Knauth L. P. (2005) Paleo3 219, 5369. [6] Hren M. T. (2009) Nature 462, 205-208. [7] Robert F.
and Chaussidon M. (2006) Nature 443, 969-972. [8] Marin J.
et al. (2010) Geochim. Cosmochim. Acta 74, 116-130.
[8] Marin-Carbonne J. et al. in prep.
www.minersoc.org
646
Goldschmidt Conference Abstracts
Ion microprobe high precision
measurements of oxygen and
magnesium isotopic compositions in
extraterrestrial materials
MARC CHAUSSIDON AND CLAIRE ROLLION-BARD
CRPG-CNRS, Nancy Université, BP 20, 54501 Vandoeuvrelès-Nancy, France
(*correspondence: [email protected]).
Two key isotope systems in cosmochemistry are oxygen
isotopes (non mass dependent oxygen isotope variations, i.e.
"17O, are ubiquitous in meteorites, especially in the high
temperature components of chondrites) and Mg isotopes (26Mg
radiogenic excesses, i.e. #26Mg*, are due to the in situ decay of
short-lived 26Al with a half life of 0.73 Myr). Because of the
presence of Al/Mg variations and of mineralogical variations
in chondrites at the micrometer scale, ion microprobe is the
only technique which offers the appropriate spatial resolution
to unravel the "17O and #26Mg* systematic.
Recent developments using multicollectors ims 1270 and
ims 1280 HR2 large radius Cameca ion microprobes allow to
reach a precision (2 sigma error) better than 0.01 ‰ for
#26Mg* and better than 0.04‰ for "17O, for sputtered volumes
of 20µm diameter and less than 1µm depth (in Mg-rich
silicates and oxides).
Such high precisions transform the "traditional" O and Mg
isotopes into "new" isotopic systems in meteorites. In the case
of 26Al for instance, the homogeneity of the distribution of 26Al
(which is a prerequisite to its use as a precise chronometer)
can be quantified for the first time by comparing chondrules to
the solar system Mg isotopic growth curve [1]. 26Al model
ages can be calculated in chondrules or in Al-free phases from
their Mg isotopic composition [2]. These model ages in Mgrich olivines from type I chondrules can be compared to high
precision "17O values to identify the origin of the olivines and
to test whether they could be fragments of the mantles of
planetesimals which differentiated very early in the disk [3].
[1] Villeneuve J., Chaussidon M., Libourel G. (2009) Science
325, 985-988. [2] Villeneuve J., Chaussidon M., Libourel G.
(2011) Earth Planet. Sci. Lett. 301, 107-116. [3] Libourel G.,
Chaussidon M. (2011) Earth Planet. Sci. Lett. 301, 9-21.
Mineralogical Magazine
Average Nd-Hf isotopic compositions
and model age of the upper
continental crust
C. CHAUVEL1, M. GARCON1, N.T. ARNDT1, S. GALLET2
2
AND B.M. JAHN
1
2
ISTerre, BP 53, 38041 Grenoble Cedex 9, France
Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
Establishing the average chemical and isotopic
composition of the upper continental crust as well as its model
age is difficult due to the diversity in compositions and ages of
this major Earth reservoir. Estimates exist for major and trace
elements as well as for some isotopic systems, but not for the
Nd-Hf isotopic couple. In 1999, Vervoort et al. [1] defined the
Nd-Hf “crustal array” and showed that Nd and Hf are
correlated in crustal rocks of various ages and origins, but they
could not define an average value.
Here we estimate the average composition of upper
continental crust using two complementary types of
sedimentary materials: (1) loess because they represent wellmixed materials from large areas of upper continental crust;
(2) beach placers because they concentrate heavy and resistant
minerals such as zircon and monazite. We determined the Hf
and Nd isotopic compositions on samples from various
locations in Western Europe, Tajikistan, China, Argentina,
Africa, USA and Australia.
The loess have remarkably uniform Nd and Hf isotopic
compositions and the average value plots on the “mantle
array” within the field of crustal materials. Placers have more
variable compositions linked to the age of the drained area.
Indeed, samples from Europe, South Africa, Eastern Australia
and USA have compositions comparable to the loess, but the
Western Australian placers have significantly less radiogenic
values due to the presence of Archean terranes in the source
area.
Combining the constraints provided by the loess and the
placers, we suggest that the following Nd and Hf
characteristics: !Nd = -10.3 ± 1.2 and !Hf = -13.8 ± 4.2. The
corresponding model age is 1.75 Ga, a value in the young side
of other estimates.
[1] Vervoort et al. (1999) EPSL 168, 79-99.
www.minersoc.org
Goldschmidt Conference Abstracts
Mobility of rare earth elements
during igneous rocks weathering and
associated stream water transport
(Malaval catchment, Massif Central,
France)
L. CHAUX , T. ROUTIER , O. POURRET , M. STEINMANN
2
AND S. BONTEMPS
1
1
1
2
HydrISE, LaSalle Beauvais, 60026 Beauvais cedex, France
([email protected])
2
UMR 6249 Chrono-Environnement, Univ. Franche-Comté,
25030 Besançon cedex, France
1
Rock alteration occurs within the critical zone at the
interface between atmosphere, biosphere, hydrosphere and
lithosphere. It is a major process within the global biogeochemical cycle and contributes also to the evolution of
landscapes. Chemical weathering dissolves partially or
completely bedrock minerals to form weathering profiles, and
dissolved ions are transported by surface and underground
runoff to the oceans. In order to establish a link between the
distribution patterns of the rare earth elements (REE) in stream
water and bedrock, a detailed alteration study of the granitic,
gneissic and basaltic bedrocks of a small mountain catchment
was realized (Malaval catchment, Massif Central, France).
The mineralogy of fresh and weathered samples was
determined by microscopy and XRD. Major and trace
elements were determined by ICP-AES and ICP-MS. A
comparison between the REE patterns of the more altered
horizons of each profile and the < 0.22 µm water fraction of
the Malaval stream has been realized in order to determine the
influence of the different bedrocks on stream water chemistry
[1]. Results suggest similar alteration mechanisms for granite
and gneiss, which is mainly controlled by the dissolution of
plagioclase leading to losses of Na2O, CaO, SiO2 and Al2O3.
Mobilization of K2O can be related to fracturing of K-feldpar,
whereas the evolution of the REE patterns is mainly controlled
by the distribution of zircon. In the alteration profiles on
basalt, olivine is the first mineral to be altered into orange
oxides leading to a mobilization of MgO. The transformation
of plagioclase into clays is accompanied by losses of Na2O
and CaO. Lowered iron concentrations can be related to
fracturing of pyroxene. A comparison between the REE
patterns of the most altered horizons of the different
weathering profiles suggests that water chemistry of the
adjacent Malaval stream is mainly controlled by basalt
weathering. In order to confirm this finding, sequential
leachings have been performed on basalt samples and
compared with stream water.
Spatial and temporal variability of
fluid and gas chemical composition at
the Lucky Strike hydrothermal vent
site (Mid-Atlantic Ridge)
V. CHAVAGNAC, C. BOULART, C. MONNIN AND
A. CASTILLO
Geosciences Environement Toulouse, 14 Avenue Edouard
Belin, 31400 Toulouse, FRANCE
([email protected])
Numerous acidic submarine hydrothermal sites have been
discovered, sampled and studied along the Mid-Atlantic ridge
between 14ºN and 38ºN near the Azores hot spot. Most
hydrothermal systems lie on basaltic substratum and only a
few of them on ultramafic rock substratum. The Lucky Strike
hydrothermal field was discovered in 1992 during the joint
US-French FAZAR expedition on a volcanic segment at
37º50’N at 1700m water depth. The high-temperature
hydrothermal fluids (up to 328ºC) have been collected in 1993
and 1994. The chemical composition of fluid and gas emitted
at this site indicate variable chlorinities lower than seawater,
low hydrogen sulfide, low metal concentrations and high gas
contents. The distinct chemical end-members argue for a
significant geographic control of the venting system and fluid
chemistry is strongly affected by phase separation at depth.
The Lucky Strike hydrothermal field was visited during
the BATHYLUCK and MOMARSAT cruises in 2009 and
2010, respectively, in order to assess the spatial and temporal
variability of the hydrothermal fluid and gas chemical
composition. Numerous fluid discharges on the western side
the lava lake were collected as limited chemical were acquired
thus far. A maximum temperature of 340ºC was measured at
South Crystal. Based on the distribution of element
concentrations, fluid chemistry is strongly affected by phase
separation at depth as well as the geographic control of fluid
plumbing system. Our results indicate that 3 different fluids
are feeding the Lucky Strike field (1: Eiffel Tower,
Montségur; 2: White Castle, Isabel, Cypress; 3: Y3, Nuno,
Crystal, South Crystal, Sintra). The concentrations of CH4 and
CO2 have increased since 1994 at Eiffel Tower, Sintra,
Montségur and Y3, while the N2 concentrations have all
decreased significantly. The H2 concentrations have stayed
stable at Eiffel tower while increasing at Y3 but decreasing at
Montségur. CH4 is generated by water-rock interaction by
Fischer-Tropsch caalysis of CO2 reduction.
[1] Steinmann & Stille (2008) Chem. Geol. 254, 1-18.
Mineralogical Magazine
647
www.minersoc.org
648
Goldschmidt Conference Abstracts
The noble gas and halogen
composition of the
hydrated oceanic crust
D. CHAVRIT1*, R. BURGESS1, C. BALLENTINE1,
B. WESTON1 AND D. TEAGLE2
S.E.A.E.S, The University of Manchester, Manchester, UK
(*correspondence: [email protected])
2
National Oceanography Centre, University of Southampton,
Southampton, UK
1
Mantle heavy noble gases have a remarkable similarity to
those found in marine pore fluids [1,2]. This implies a
significant contribution of these gases into the mantle recycled
through subduction zones. In order to better constrain the
quantity and character of noble gases available for subduction,
we are reassing the major host phases of noble gases in presubducted material.
We have acquired, from different ODP sites, a sample
suite that is representative of the altered oceanic crust. Noble
gas (He, Ne, Ar, Kr and Xe) isotopes and abundances are
being determined using crushing release measured with an
upgraded VG5400 mass spectrometer.
Preliminary results from four altered basalts (ODP sites
504B and 1256D in the Southeast Pacific Ocean, respectively
5.9 and 15 Ma) show Ne to Xe isotopically identical to air.
3
He/4He ratios are uniform at 6.82±0.42 (R/Ra). Heavy noble
gas elemental ratios fall within a narrow range, with 130Xe/36Ar
and 84Kr/36Ar ratios varying between seawater values and
values enriched in Xe and Kr and indistinguishable from
mantle values [1]. The range of 130Xe/84Kr, varying by up to a
factor 2.5, suggests that different trapping or fixation sites
could control such compositions.
This is supported by an observed correlation of increase of
the 132Xe/36Ar ratio relatively to 84Kr/36Ar with crushing step in
the same sample, which does not seem related to air
contamination. This could be representative of the different
phases retaining different amounts of heavy nobles gases.
These measurements will be extended to include halogen
determinations which are tracers of marine pore fluids and
seawater interaction [2]. Analysing noble gases and halogens
in basalts characterized by different alteration patterns and in
gabbros and sediments will allow the identification of the
noble gas host phases, as well as the controls of the seawater
noble gases interaction with the oceanic crust.
[1] Holland & Ballentine (2006), Nature 441, 186-191. [2]
Sumino et al. (2010), EPSL 294, 163-172.
Mineralogical Magazine
Experimental constraints on
magmatic wolframite
X. CHE123, R.L. LINNEN23 AND R.C. WANG1
School of Earth Sciences and Engineering, Nanjing
University, ([email protected])
2
Dept. Earth Sciences, University of Western Ontario
3
Dept. Earth & Enviromental Sci., Univ. of Waterloo
1
Wolframite is normally a hydrothermal mineral but at the
Yaogangxian tungsten deposit, Hunan, China it also occurs as
an apparent magmatic phase disseminated in a mediumgrained two-mica granite. The magmatic wolframites are
tabular crystals, hundreds of !m long, in planar contact with
with magmatic K-feldspar and quartz. The major elements of
magmatic wolframite are similar to hydrothermal crystals in
quartz veins from the main zone of mineralization at the
deposit. However, Zr, Nb, Ta and Mo are more abundant in
magmatic wolframites compared to hydrothermal varieties.
The solubilities of synthetic hubnerite (MnWO4) in fluxrich water saturated haplogranitic melts have been determined
at 850° to 700°C and 2000 bars in order to test the magmatic
hypothesis. The melts contain 1.1, 1.7 and 2.02 wt % of Li2O,
P2O5 and B2O3, respectively. Up to 6 wt% fluorine was added
as AgF; the ASI of the melt is close to 1, but if Li is
considered to be an alkali element, the melts are alkaline.
Hubnerite solubility is weakly dependent on F. At 800°C the
solubility products for hubnerite (Ksp) range from 38x10-4
mol2/kg2 for a 0 wt% F melt to 69x10-4 mol2/kg2 for a 6 wt% F
melt. Hubnerite solublity is strongly temperature dependent.
Ksp for a 6 wt% F melt decreases from 162x10-4 mol2/kg2 at
850°C to 17x10-4 mol2/kg2 at 700ºC. Another potential control
on hubnerite solubility is fO2. The Ksp is 38x10-4 mol2/kg2 at an
fO2 near Ni-NiO, 53x10-4 mol2/kg2 using a Co filler rod and
69x10-4 mol2/kg2 using Ti filler rod (see [1] for approximate
fO2 values). The weak variation of solubility with fO2 implies
that the predominant oxidation state of W in the melts is +6,
even at reduced conditions.
The above experimental solubilities are too high to support
the magmatic wolframite hypothesis, however the melts in
these experiments are alkaline and solubilities are lower in
subaluminous compositions [2]. Because of the strong
temperature dependence, magmatic wolframite may
nevertheless occur in nature, but the melts should have
crystallized at a low temperature and be subalkaline to
peraluminous in composition.
[1] Matthews et al. (2003), Amer. Mineral. 88, 701-707.
[2] Linnen and Cuney, (2005), Geol. Assoc. Can Short Course
Vol. 17, 45-67.
www.minersoc.org
Goldschmidt Conference Abstracts
Silica coatings on young Hawaiian
basalts: Constraints on formation
mechanism from silicon isotopes
Origin of the late Mesozoic high-Mg
diorites from the North China
Craton: Petrological and Os isotopic
constraints
S.M. CHEMTOB1*, J.A. HUROWITZ2, Y. GUAN1,
K. ZIEGLER3, J. M. EILER1 AND G.R. ROSSMAN1
California Institute of Technology, Pasadena, CA 91125
(*[email protected]ps.caltech.edu)
2
Jet Propulsion Lab, Caltech;
3
UCLA, Los Angeles, CA
1
Young basalts from Kilauea, on the big island of Hawai’i,
frequently feature visually striking, white, orange and blue
coatings, consisting of a 10-50 µm layer of amorphous silica,
capped, in some cases, by a ~1 µm layer of Fe-Ti oxide [1].
The coatings provide an opportunity to study the early onset of
acid-sulfate weathering, a process common to many volcanic
environments. Silicon isotopes fractionate with the
precipitation of clays and opaline silica, and have been
demonstrated to be an indicator of weathering intensity [2,3].
Here we report in situ measurements of !30Si of the silica
coatings and their implications for coating formation.
The analyzed coated basalt was collected from 1997
overflow lavas at the rim of the Pu’u O’o cone. The sample
was mounted in cross section. Analyses were conducted on a
Cameca 7f-Geo ion microprobe with a O- primary beam (~30
µm spot) and two Faraday cups. The silica coating was
measured against the Rose Quartz standard (RSQ). We tested
whether the coating’s amorphous structure introduced a matrix
effect by analyzing quartz and fused glass of the same
composition (Ge214). Measurements of those materials were
the same within error, so although we have not ruled out other
relevant matrix effects (e.g. water content), we accept RSQ as
a viable standard for analyzing amorphous silica.
The silica coating was determined to have !30Si = -1.8 ±
1.0‰ (2+). Hawaiian basalts have !30Si % -0.5‰ [2], so the
silica coatings are ~1‰ lighter than the substrate. The sign of
this fractionation is consistent with previously reported values
for secondary silica [2-4], and implies that, although the silica
coatings have a residual/leaching morphology [1], Si was
mobile during coating formation. Basalt dissolved in acidic
solution, then a fraction of aqueous Si precipitated as
amorphous silica; the remaining dissolved Si (tens of percent)
was lost from the system. Ongoing work includes
confirmation of the SIMS analysis by ICP-MS and replication
of observed coating morphologies and isotopic properties in
flow-through alteration experiments.
[1] Chemtob et al. (2010), JGR 115, 2009JE003473.
[2] Ziegler et al. (2005), GCA 69, 4597-4610. [3] Georg et al.
(2007), EPSL 261, 476-490. [4] Douthitt (1982) GCA 46,
1449-1458.
Mineralogical Magazine
649
B. CHEN*1,2, C. WANG2, A.K. LIU2 AND L. GAO2
1
College of Geology & Prospecting Engineering Program,
Xinjiang University, Urumqi 830046, China
(*correspondence: [email protected])
2
School of Earth and Space Sciences, Peking University,
Beijing 100871, China
The Mesozoic Tietongou & Jinling high-Mg dioritic
plutons from the north China craton contain plagioclase (4555%), hornblende (20-40%), Cpx (10%) and minor Opx,
olivine, biotite, quartz, and accessory sphene, magnetite and
apatite. The diorites (SiO2 = 52-63%) show high MgO (9.23.5%), Sr (470-980 ppm), Ni (15-157 ppm), Cr (35-416 ppm)
and Co (20-35 ppm), with ISr = 0.7052-0.7083 and !Nd(t) = -4.5
to -15. The contradictory geochemical features of the high Sr
and high compatible Ni, Co and Cr are reminiscent of the
sanukitoids of late Archean times.
Traditionally, the Tietongou and Jinling high-Mg dioritic
plutons were suggested by most workers to have originated
from partial melting of the eclogitized Archean mafic lower
crust delaminated to mantle depths due to crustal thickening,
followed by interaction of the resultant dioritic melts with
mantle peridotites during magma ascent, during which the
melts gained additional MgO. However, our petrological and
Os isotopic data suggest that the dioritic plutons formed from
a process of magma mixing between basaltic magma and
granitic crustal melt formed due to underplating of the basaltic
magma in the lower crust. In this model, no crustal thickening
and delamination of the lower mafic crust is required. Main
arguments are as below. (1) Plagioclase shows compositional
and textural disequilibrium, as revealed by the eroded calcic
core (An78-60) surrounded sharply by a mantle with much lower
An contents (38-16), which is typical of magma mixing
between mafic and felsic magmas. (2) Hornblende shows
complex compositional zoning, with low TiO2 zones (0.8%)
surrounded by high TiO2 zones (2.7%), suggesting an input of
high temperature basaltic magma during magma evolution.
This agrees with the complicated compositional zoning of
Cpx. Opx is always rimmed by Cpx, indicating a reaction
relationship. This, along with the presence of millimeter-scale
relict aggregates of olivine + Opx, suggests that the dioritic
plutons are actually mixture of melts plus xenoliths. (3) The
dioritic plutons have Os isotopic ratios in the range 0.33-1.22.
If the dioritic plutons were formed by interaction of the melts
from the delaminated Archean lower crust with mantle rocks,
the required proportions of the latter would be unreasonably
high (30-85%). The Os isotopic data can be reasonably
explained by our magma mixing model: the majority of the
dioritic plutons were basaltic magma from an enriched mantle
source, which mixed with subordinate crustal melts (9-35%) in
the lower crust.
www.minersoc.org
650
Goldschmidt Conference Abstracts
Hydrothermal circulation and
post-obduction hydration &
carbonation of oceanic lithosphere !"#$%!&#$'()*'+,-./)'01+2+304'125*-'
+6'78()'+390+:02/
C. CHEN*, C. ANDRONICOS, L.M. CATHLES AND
W.M. WHITE
Department of Earth and Atmospheric Sciences, Cornell
University, Ithaca, NY 14853
(*correspondance: [email protected])
We report whole-rock isotopic analyses on 33 samples
collected from Nakhl, Sumail and Wadi-Tayin nappes of
Oman ophiolite, sampling a transect from upper gabbros to the
Moho Transition Zone. 87Sr/86Sr and (18O varied as follows:
(1) upper gabbros: 87Sr/86Sr 0.7032~0.7080, (18O 2.4~6.3;
(2) middle gabbros: 87Sr/86Sr 0.7031~0.7060, (18O 5.3~6.1;
(3) lower gabbros: 87Sr/86Sr 0.7031~0.7064, (18O 3.4~6.7;
(4) Moho peridotites and carbonates, 87Sr/86Sr 0.7035 ~
0.7086, (18O 2.95 ~ 30.57. These data together with
petrographic studies confirmed that the entire ophiolite section
below sheeted dikes was subjected to >300˚C hydrothermal
alteration during its formation and that locally temperatures
exceeded 500˚C. High (18O and 87Sr/86Sr in excess of
Cretaceous
seawater
(0.7079)
clearly
show
that
serpentinization and carbonation of the ophiolite have also
occurred post-obduction. Four out of five samples with
87
Sr/86Sr > 0.7079 are from Moho Transition Zone: two
samples magnesite rocks with (18O ~30, the other two are
serpentinites with (18O > 7. One tiger gabbro has 87Sr/86Sr of
0.7080 and (18O of 2.4. Leaching experiments show that the
radiogenic Sr is not restricted to carbonate vein minerals. Thus
original isotopic information is easily overprinted by the late
stage processes if the peridotites are entirely altered into
serpentinites or carbonates. On the other hand, gabbros, which
have cracks filled with carbonates but not fully altered, can
preserve hydrothermal alteration information during
formation.
!
Mineralogical Magazine
Atoll garnet in the Yukahe UHP
eclogite: Evidence for melt/fluid
activity during the eclogitic facies
metamorphism
D.L. CHEN, L. LIU AND X.M. LIU
State key Laboratory of Continental Dynamics, NW Univ.,
Xi’an, 710069, PR China. ([email protected])
The typical mineral assemblage of the Yukahe eclogite
from the North Qaidam in NW China is Grt+Omp+Phen+Rt+
Coe. Garnets in the eclogite show two shapes of normal
porphyroblast garnet and atoll texture garnet. In which, the
normal garnet cores contain mineral inclusions of Pl, Amp,
Ap, Zoi, Ep and Qz, and change into Omp, Phen and Rt in the
mantles, the rims are clean with few inclusion. EMP analyses
revealed a compositional zoning with a bell-shaped decrease
of Spe and a bowl-shaped increase of Pyr content towards the
rim and a small decrease of Pyr in the outmost rims. The atoll
garnets commonly consist of a euhedral ring and a
island/peninsula core of garnet, eclogite facies multiphase
solid inclusions of Omp, Phen, Grt, Rt and Qz filled between
the core and the ring. In a few cases the garnet core is totally
missing and filled with a single Phen. The island cores contain
the same mineral inclusions as those of in the normal garnet
cores; the garnet rings, like the rims of the normal garnet, are
clean without any inclusions. A successive compositional
zoning with Spe content decrease and Pyr content increase
were revealed from the core to the ring, similar to that of the
normal garnets. Omp and Phen occur in the matrix and within
the atoll have almost the same composition. EBSD analyses
demonstrate that the island/ peninsula garnet cores or fractions
inside atolls have crystallographic orientations identical to that
of the atoll rings. LA-ICP-MS analyses indicate that Omps in
both the matrix or within the atoll display the same REE
patterns with a peak in MREEs and a pronounced depletion in
both LREEs and HREEs. Whereas, the rings of the atoll
garnet, ralitive to the core, show a distinct enrichment in
MREEs and a visible depletion in HREEs. The mineral
assemblage and their composition within atoll garnet are as
same as that of the peak metamorphism of the Yukahe eclogite
except for Coe, combined with the existing geochemical and
chronological studies of leucosomes interbeded with the UHP
eclogite body, it suggests that atoll garnets in the Yukahe
eclogite formed under eclogite facies conditions during almost
the peak metamorphism. It provides good evidence for
melt/fluid activity during UHP metamorphism.
www.minersoc.org
Goldschmidt Conference Abstracts
Provenance of early sedimentary
sequences in the Tethyan Yunnan,
SW China: Age and Hf isotope of
early Archean zircons
F. CHEN , B.-X. LIU , S.-Q. LI AND W. SIEBEL
1
1
1
2
CAS Key Laboratory of Crust-Mantle Materials and
Environments, University of Science and Technology of
China, Hefei 230026, China
2
Institut für Geowissenschaften, Universität Tübingen, 72074
Tübingen, Germany
1
This study presents U-Pb ages and Hf isotopic
composition of detrital zircons from Cambrian to Ordovician
sedimentary rocks exposed in the Tethyan belt of western
Yunnan, SW China. This orogenic belt belongs to the eastern
Tethyan belt in SW Asia. It is composed of several microcontinents or continental block of different affinities.
The early Paleozoic sedimentary rocks, collected from the
Baoshan block, contain detrital zircons of different
crystallization ages ranging from about 3800 Ma to 550 Ma
(207Pb/206Pb age), but mostly clustering around 1.0 Ga and 2.4
Ga. About 10% zircon grains yield 207Pb/206Pb ages older than
3.0 Ga Ma, indicating significant sedimentary source(s) of
early Precambrian crustal material. Initial !Hf values of the
detrital zircons vary from -34 to +15, while TDM values of
zircons, calculated from Lu-Hf isotopic composition, range
from about 1.0 Ga to 4.0 Ga with peaks around 1.8 Ga and
2.8-3.0 Ga. Their Nd isotopic composition of whole-rocks
(TDM values from 1.8 Ga to 2.5 Ga) also imply significant
put-in of old crustal material.
The Baoshan block is considered as the northern part of
the Sibumasu microcontinent in the eastern Tethyan orogenic
belt. From the analytical results of detrital zircons above, we
propose that the sedimentary sources of the early Paleozoic
sequences in the western Yunnan originated from Archean and
Paleoproterozoic terrains most likely in India and NW
Australia.
Mineralogical Magazine
651
A study of the column bioleaching of
Xianshan uranium ore
GONGXIN CHEN 1,2*, JINHUI LIU1 AND ZHANGXUE SUN1
East China Institute of Technology , Fuzhou 344000 , China
(*correspondence: [email protected])
2
China University of Geosciences, Beijing 100083 , China
1
The samples of uranium ore were obtained from the U
mine at Xianshan, Jinagxi Province (China). Quantitative
chemical analysis showed that the uranium ore had a mediate
carbonate content (CO2~1.42%), that pyrite was the most
important sulphur mineralization (~1.43%) and that the
principal components were silicates. The most common
uranium mineralization in the vein, pitchblende, appears as
UO2. The particle size of the ore is less than 10mm.
Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans
and Acidithiobacillus thiooxidans isolated from the mine
waters of the Xianshan uriamium depoist were used in this
bioleaching experiment.
The column was made of PVC with 300cm heigh and
80cm diameter. Once the column was fully charged, it was
irrigated with 20g/L H2SO4 about 20 days to reach the correct
degree of acidity, after which the inoculum was introduced
and irrigation continued until the end of the experiment.
Sample volumes of liquid were extracted periodically and the
pH and redox potential (Eh) were measured. The U308, FeTotal,
and Fe2+ content were also analyzed.
Mixed bacteria play an important role in the leaching
process. In 120 days, the recovery of pyrite leaching is about
70%, and of uranium is up to 90%. Acid consumption is very
low, about 6.8%. Results also show that U leaching and pyrite
leaching are closely related during bioleaching. With the
increase of pyrite leaching recovery, uranium leaching
recivery is also increased. Due to some pyrite in U mine,
biological leaching have good benefit to extract U from the
ore compared with those traditional leachings such as heap
leaching with acid and stirring tank leaching with MnO2.
This study is financially supported by Foundation of
Jiangxi Educational Committee for Youths (GJJ11155).
www.minersoc.org
Goldschmidt Conference Abstracts
652
Precise determination of the Ca
isotopic compositions by
thermoionization mass spectromery
Interaction of NOM and NZVI:
Implication for NZVI’s toxicity and
reactivity in the environment
H.-W. CHEN1*, J.-C. CHEN1, J.J. SHEN1, D.-C. LEE1 AND
T. LEE12
Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan,
ROC (*correspondence: [email protected])
2
Institute of Astronomy and Astrophysics, Academia Sinica,
Taipei, Taiwan, ROC
1
High precision Ca isotopic measurements have been set up
using the thermo ionization mass spectrometry (TIMS). With
the improved sample loading technique, it is possible to
sustain a Ca ion current of 1.5~3nA for more than an hour for
high precision Ca isotopic measurements. Using this
procedure, typical analytical precision (2$) for 40Ca/44Ca,
43
Ca/44Ca, 46Ca/44Ca, and 48Ca/44Ca are 1.6, 0.31, 7.5, and 0.68
epsilon (!; in parts per 104), respectively, after normalizing to
42
Ca/44Ca = 0.31221 [1]. Four separate runs are usually taken
for individual sample to ensure the reproducibility of the
isotopic measurements, and the analytical uncertainty (2$) can
be further reduced to 0.87, 0.13, 4.6, and 0.42! for 40Ca/44Ca,
43
Ca/44Ca, 46Ca/44Ca, and 48Ca/44Ca, respectively, if the data of
all four runs are combined. With the improved analytical
precision, in particular for the less abundant 43Ca and 48Ca, it is
possible to re-examine the Ca isotopic heterogeneity in
terrestrial and meteoritic materials, and to explore the
preserved non-linear stellar nucleosynthetic signatures in
meteorites and homogenization process in the early solar
system.
[1] Russell et al. (1978) GCA 42, 1075-1090.
JIAWEI CHEN1, 2*, ZONGMING XIU2,
GREGORY V. LOWRY 3 AND PEDRO J. J. ALVAREZ 2*
State Key Laboratory of Geological Process and Mineral
Resources, China University of Geosciences, Beijing
100083, China
(*correspondence:[email protected])
2
Dept. of Civil & Environmental Engrg., Rice University,
Houston, TX 77005, USA
3
Dept. of Civil & Environmental Engrg., Carnegie Mellon
University, Pittsburgh, PA 15213, USA
1
Nano-scale zero-valent iron (NZVI) particles are
increasingly used to remediate aquifers contaminated with
hazardous oxidized pollutants such as trichloroethylene
(TCE). However, the high reduction potential of NZVI can
result in toxicity to indigenous bacteria and hinder their
participation in the cleanup process. Here, we report on the
mitigation of the bactericidal activity of NZVI towards gramnegative Escherichia coli and gram-positive Bacillus subtilis
in the presence of Suwannee River humic acids (SRHA),
which were used as a model for natural organic matter
(NOM). B. subtilis was more tolerant to NZVI (1 g/L) than
E. coli in aerobic bicarbonate-buffered medium. SRHA (10
mg/L) significantly mitigated toxicity, and survival rates
increased to similar levels observed for controls not exposed
to NZVI. TEM images showed that the surface of NZVI and
E. coli was surrounded by a visible floccus. This decreased the
zeta potential of NZVI from -30 to -45 mV and apparently
exerted electrosteric hindrance to minimize direct contact with
bacteria, which mitigated toxicity. H2 production during
anaerobic NZVI corrosion was not significantly hindered by
SHRA (p > 0.05), However, NZVI reactivity towards TCE (20
mg/L), assessed by the first-order dechlorination rate
coefficient, decreased by 23% (from 0.0178 ± 0.0007 h-1 to
0.0137 ± 0.0004 h-1). These results suggest that the presence of
NOM offers a tradeoff for NZVI-based remediation, with
higher potential for concurrent or sequential bioremediation at
the expense of partially inhibited abiotic reactivity with the
target contaminant [1].
This study was sponsored by the USEPA (R833326), the
Fundamental Research Funds for the Central Universities
(2010ZD14, 2010ZD13), National Program of Control and
Treatment of Water Pollution (2009ZX07424-002), Program
for New Century Excellent Talents in University (NCET-070769), and China Geological Survey (Ke [2011]-01-66-07).
[1] Chen et al. (2011) Water Research 45, 1995-2001.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Research on pretreatment of highly
concentrated dye-printing
wastewater using surplus sludge
together with powder ash
JINGYING CHEN
Department of Civil and Environmental Engineering, East
China Institute of Technolog, Fuzhou344000, China
([email protected])
The pretreatment craft is extremely essential in the
processing of dye-printing waste water. Using surplus sludge
together with the powder ash as the flocculants to pretreat
highly concentrated dye-printing wastewater, which leads to
the remarkable reduction of the discharge monitoring index in
the wastewater ! chroma, the suspended solid and the
chemical oxygen demand. [1]
This article has conducted the experimental study uses
surplus sludge together with the powder ash as the flocculants
to pretreatment highly concentrated dye-printing waste water.
The results show that through control the volume ratio of the
surplus sludge and coal ash, static time and so on, when the
volume ratio is the dye-printing waste water/Surplus
sludge/coal ash =60: 1: 8, and the static time between 20 ~ 40
minutes, there is a remarkable reduction of the discharge
monitoring index in the waste water–chroma and the chemical
oxygen demand. The finding provides the experiment basis for
reducing the consequent biochemical treatment loads
effectively reducing the running cost for highly concentrated
dye-printing waste water disposal exploring the industrialized
technical designing direction and the way on using the waste
to deal with the waste.
[1] Zheng Z, Xu J , Sun Y Y, et al. Synthesis and chiroptical
properties of optically active polymer liquid crystals
containing azobenzene chromophores [J ]. Poly Science, 2006,
44 (10) : 3210- 3219.
653
Mass-dependent fractionation and
mass-independent fractionation of Hg
isotopes in aqueous environment
JIUBIN CHEN1,2, HOLGER HINTELMANN2 AND
XINBIN FENG1
State Key laboratory of Environmental Geochemistry,
Institute of Geochemistry, Chinese Academy of Sciences,
46 Guanshui Road, Guiyang, GuiZhou 550002, China
2
Chemistry Department, Trent University, 1600 West Bank
Drive, Peterborough, Ontario, K9J7B8, Canada
1
Preliminary studies have demonstrated both massdependent fractionation (MDF) and mass-independent
fractionation (MIF) of Hg isotopes in the environment (1) and
the potential for their application in biochemistry and
geochemistry. However, the majority of previous work has
focused either on developing reliable MC-ICP-MS
measurements or on monitoring isotopic variation of Hg in
solid samples and in Hg-enriched synthetic solutions. Little
has been reported for Hg isotope geochemistry in natural
aqueous environment because of the very low Hg
concentrations (several ng/L).
Precipitation samples and water samples from different
aquatic systems (remote lakes, contaminated rivers,
groundwater) were analyzed for Hg isotopic composition after
pre-concentration using a new pre-concentration method (2).
The results displayed evident MDF and MIF of Hg isotopes in
natural aqueous environment. All samples displayed a total
#202Hg variation of 2.42‰ (-1.68‰ to 0.74‰), with lower
values for precipitation and lake waters and higher values for
contaminated river waters. Unlike waters from contaminated
rivers, precipitation samples displayed positive MIF of odd Hg
isotopes, contrast to the predicted result from previous studies.
Moreover, our results confirmed the observation of MIF of
odd Hg isotopes (200Hg) in precipitation samples (3), implying
that the (atmospheric) process introducing the MIF for even
Hg isotopes may be different from that producing MIF of odd
isotopes in the aqueous environment. More research is
required to fully understand the behavior of Hg isotopes in the
hydrosphere.
[1] Bergquist, B. Sci. 2007; [2] Chen J-B. JAAS, 2010;
[3] Gratz, L. EST 2010.
Mineralogical Magazine
www.minersoc.org
654
Goldschmidt Conference Abstracts
The evidences of the Initial broken
for the Shangdan Ocean:
Geochronology and geochemistry of
the Muqitan Formation, in North
Qinling
JUN-LU CHEN, XUE-YI XU, HONG-LIANG WANG AND
PING LI
Xi’an Center of Geological Survey(Xi’an Institute of Geology
and Mineral Resource), CGS, Xi’an, Shaanxi 710054,
China
The Muqitan ophiolitic mélange found within the Muqitan
Formation near Muqitan region, the North Qinling Orogen.
They mainly consist of amphibolite with minor meta-gabbro
and meta-chert. Zircon LA-ICP-MS U-Pb dating yields an age
of 762.5±4.6Ma for the amphibolites, interpreted as
crystallization time, The amphibolites are characterized by
low TiO2 (0.57%~2.16%), relatively low K2O/Na2O ratios
(0.06~0.55) and moderate-high Mg# (45.3~68.7). They are
geochemically similar to low-Ti tholeiites. The Muqitan
amphibolites have low REE contents, with differentiated
LREE/HREE patterns and no Eu anomalies on the chondritenormalized REE diagram, analogies to E-MORB. The
amphibolites display an enrich elements Rb, Ba,Th, and La
pattern, low (87Sr/86Sr)i ratios of 0.7038 to 0.7040 and high
#Nd(t) values of +4.1 to +6.9, suggesting a mantle origin,
similar in composition to FOZO-like source. Their (Th/Nb)N,
Nb/La and Ba/La ratio features indicate that these amphibolite
have been experienced varying degrees of crustal
contamination. All these data, combined with the regional
geological features demonstrate that the Muqitan amphibolites
are interpreted as remnants of the Shangdan ancient oceanic
crust that would have formed during the inception of the
oceanic open at ca. 762.5 ±4.6Ma.
Acknowledgment:: This study was supported by the
National Natural Science Foundation of China (Grant No.
)
Mineralogical Magazine
Deposition and remobilization of
oxidized multiwalled carbon
nanotubes on silica surfaces:
Implications for environmental fate
and transport
KAI LOON CHEN* AND PENG YI
Department of Geography and Environmental Engineering,
Johns Hopkins University, Baltimore, Maryland 21218
(*correspondence: [email protected],
[email protected])
Carbon nanotubes (CNTs) are increasingly used in
commercial and industrial applications because of their
superior mechanical and electronic properties. With CNTcontaining products already available in the market, it is
inevitable that some CNTs will be released into natural aquatic
systems. In order to predict the fate and transport of CNTs in
surface water and groundwater systems, it is important to
understand the interaction between CNTs and natural surfaces.
In this study, we investigate the deposition and remobilization
of oxidized multiwalled carbon nanotubes (MWNTs) on silica
surfaces with a quartz crystal microbalance with dissipation
monitoring (QCM-D). The distributions of oxygen-containing
surface functional groups for two MWNTs are determined
using X-ray photoelectron spectroscopy in conjunction with
vapor phase chemical derivatization. Deposition kinetics of
lowly oxidized MWNTs (LO-MWNTs) and highly oxidized
MWNTs (HO-MWNTs) are compared in monovalent (NaCl)
and divalent (CaCl2) electrolytes. HO-MWNTs are found to
be more stable to deposition than LO-MWNTs in the presence
of NaCl. However, in the presence of CaCl2, the attachment
efficiency profiles of both MWNTs are comparable, which is
possibly due to Ca2+ cations having a higher affinity to form
complexes with adjacent carboxyl groups on HO-MWNTs
than with isolated carboxyl groups on LO-MWNTs.
Additionally, the deposited MWNTs can be released from
silica surfaces when they are rinsed with low ionic strength
solutions, indicating that the deposition of MWNTs is not
always irreversible. The degree of nanotube release is
observed to be dependent on the ionic strength and pH of
rinsing solutions.
www.minersoc.org
Goldschmidt Conference Abstracts
DIE model and compensation method
applied in through-casing resistivity
measurement
CHEN QING
CEEE of Huazhong University of Science and Technology,
430074Wuhan, China
Double-Injection-Electrodes (DIE) model and its
compensation arithmetic method has been proven to be very
useful for eliminating the errors caused by electrode-scale
mechanical tolerances in formation resistivity measurement
through metal case. In this paper, we found that even minor
casing joint or casing corrosion may deteriorate the
measurement accuracy. Based on theoretical analysis and selfadaptive goal oriented hp-Finite Element (FE) simulations, the
compensation effects of DIE model were estimated. The
calculated results from DIE model are always close to the real
formation resistivity no matter the metal casing is ideal or not.
Meanwhile, large errors occur in Single-Injection-Electrode
(SIE) model, where the calculated formation resistivity may
provide negative numbers when casing joint or casing
corrosion exists. The Double-Injection-Electrode (DIE) model
is predicted to have good compensation effects to many nonideal situations with uneven metal casing besides electrodescale mechanical tolerances.
Mineralogical Magazine
655
Timing of dehydration melting and
fluid flow during continental
subduction-zone metamorphism in
the Dabie orogen
REN-XU CHEN AND YONG-FEI ZHENG
School of Earth and Space Sciences, University of Science
and Technology of China, Hefei 230026, China
([email protected])
Dehydration melting of UHP metamorphic rocks and the
possible presence of supercritical fluid during continental
subduction-zone metamorphism has been revealed by
microscale observations of petrology and geochemistry.
However, a direct geochronologic constraint on partial melting
and fluid supercriticality is still lacking. This study reports for
the first time the outcrop-scale occurrence of migmatite-like
structure within UHP eclogite in the Dabie orogen.
Leucocratic veins and their host rocks were investigated by
means of petrology and zirconology. Metamorphically grown
zircons from the veins yield consistent U-Pb ages of 215±4 to
218±4 Ma; zircon trace elements indicate that they crystallized
in the presence of garnet or amphibole. Ti-in-zircon and Zr-inrutile thermometers gave variable temperatures from 537 to
758°C. Thus the veining occurred in the stage of transition
from HP eclogite-facies to amphibolite-facies retrogression
during exhumation of the deeply subducted continental crust.
On the other hand, based on the paragenesis and trace element
composition of vein minerals, vein-forming fluids are mainly
composed of SiO2 + Al2O3 + CaO + K2O + FeO + MgO + H2O
and enriched in LREE, HREE, HFSE, LILE, and Pb, Th and
U. The enrichment of HREE and HFSE suggests that the
fluids have very high capacity of dissolving water-insoluble
elements, pointing to the possible presence of supercritical
fluid. While the supercritical fluid is stable in the UHP regime,
it would separate into a hydrous melt and an aqueous fluid
during the decompression exhumation into the HP eclogite
facies. As a consequence, the vein minerals rich in the trace
elements would precipitate as a product of phase separation.
Thus, the dehydration melting of UHP metamorphic rocks is
considered as the prerequisite for local formation of
supercritical fluid in the UHP regime, whereas the phase
separation of supercritical fluid during the exhumation is
suggested as the basic cause for differential partition of trace
elements between rock-forming and accessory minerals in the
veins. Therefore, the zircon U-Pb dates on the leucocratic
veins provide a temporal constraint on the lower limit of local
melting during the continental collision.
www.minersoc.org
Goldschmidt Conference Abstracts
656
Fungal spore contributions to
subtropical aerosol particles
Hf-Nd isotope variations of late
Cenozoic Arctic intermediate water
reflect continental weathering
S.-H. CHEN AND G. ENGLING*
Department of Biomedical Engineering and Environmental
Sciences, National Tsing Hua University, Hsinchu 300,
Taiwan (*correspondence: [email protected])
Primary Biological Aerosol Particles (PBAPs), as derived
from pollen, fungi, bacteria, viruses, algae, and plant
fragments, have recently been shown to contribute sizeable
portions of atmospheric particulate matter (PM) on global
scale, specifically in coarse mode particles [1, 2]. Fungal
spores in particular constitute an important type of PBAPs [3,
4]. A new method for estimating PBAP contributions was
introduced by Bauer and coworkers by utilizing molecular
source tracers, i.e., the polyols arabitol and mannitol [5].
While conversion factors from ambient tracer concentrations
to fungal spore mass have been determined for a continental
location in Europe [4, 5], there are no reports to date regarding
the tracer characteristics of different types of fungal spores in
other areas and specifically in Asia.
Our recent investigations have shown that fungal spore
content in coarse PM can be rather high in tropical regions
with contributions up to 26% of organic carbon and up to 18%
of PM10 [6]. Ambient conditions, such as temperature and
moisture, influence biological activity, including fungal spore
release rates. Moreover, fungi species in different locations
likely have varying polyol content. Therefore, it is crucial to
determine the absolute and relative abundance of individual
polyol tracers in different fungi species (i.e., source samples),
as well as the concentrations of these tracers in ambient PM as
a function of environmental conditions.
In order to address these open questions, size-resolved PM
samples were collected at various sites across Taiwan,
including coastal, urban, rural and high-altitude sites. In
addition, various types of fungi were cultured. The polyol
tracers arabitol and mannitol, along with other carbonaceous
species, were quantified in the ambient and source samples by
high-performance anion exchange chromatography (HPAEC).
New insights into the size-dependent composition of fungal
spore tracers in subtropical PM and in specific fungi species
will be presented here.
[1] Jaenicke et al. (2007) Env. Chem. 4, 217-220. [2] Heald &
Spracklen (2009) Geophys. Res. Lett. 36, L09806 [3] Elbert et
al. (2007) Atmos. Chem. Phys. 7, 4569-4588. [4] Bauer et al.
(2008) Atmos. Env. 42, 5542-5549. [5] Bauer et al. (2008)
Atmos. Env. 42, 588-593. [6] Zhang et al. (2010) Env. Res.
Let. 5.
Mineralogical Magazine
TIAN-YU CHEN1, MARTIN FRANK1 AND
ROBERT F. SPIELHAGEN1,2
IFM-GEOMAR, Leibniz Institute for Marine Sciences,
Wischhofstrasse 1-3, 24148 Kiel, Germany
([email protected]; [email protected];
[email protected])
2
Academy of Sciences, Humanities and Literature, 55131
Mainz, Germany
1
The late Cenozoic glaciation history of the Arctic is
important for understanding the global climate system and
feedback mechanisms. However, such information from the
Arctic basin itself is limited. The combined Hf-Nd isotope
composition of past seawater in high latitudes has been
suggested as a proxy for changes in intensity and regime of
continental weathering due to fractionation processses as a
function of weathering regime.Enhanced physical weathering
during glaciations is expected to cause a more congruent
release of Hf weathered from continental rocks. So far, there
are, however, no records from the Arctic basin. We extracted
combined seawater-derived Nd-Hf isotope compositions from
the authigenic Fe-Mn oxyhydroxide fraction of two sediment
cores recovered on Lomonosov Ridge (PS2185, ACEX), in
order to reconstruct weathering regime and past circulation.
We produced "Nd (~-10.5) and "Hf (~0.4) signatures of
AIW from the core-top sediments, which agree well with
previously reported values directly determined on nearby
water samples of AIW. Over time, Hf isotopes have in general
become less radiogenic since 16 Ma, which is not observed for
Nd isotopes. Similar to Nd isotopes, clear glacial-interglacial
variations of Hf isotopic compositions were also observed in
the late Quaternary, with more radiogenic Hf isotope
signatures in glacial stages and less radiogenic Hf isotope
compositions during interglacial stages. Unlike Nd isotope
compositions of AIW, which are at present dominated by
current inputs from the North Atlantic, Hf isotope signatures
of AIW are apparently more influenced by input from local
shelf sediments and surrounding rivers. Our interpretation for
the long term Hf isotopic evolution is that they reflect
progressively more congruent weathering of rocks of the
continents surrounding the Arctic Ocean, associated with
stepwise cooling of the Northern hemisphere. Glacialinterglacial variations of Hf isotopes also seem to have been
controlled by the variable weathering regime as a function of
climate and temperature changes.
www.minersoc.org
Goldschmidt Conference Abstracts
(U-Th)/He geochronological evidence
for rapid uplift of Tianshan orogenic
belt since Miocene
CHEN WEN1*, SUN JINGBO1, JI HONGWEI2,1, LI JIE2,1,
YIN JIYUAN1, GONG JUNFENG1 AND LIU XINYU 1
Laboratory of Isotope Geology, Institute of Geology, CAGS,
Beijing, 100037 China
(*correspondence: [email protected])
2
China University of Geosciences (Beijing), Beijing, 100083
China
1
The Tianshan orogenic belt, lying across Central Asia, is
an important part of the Central Asian Orogenic Belt, which
formed by the continental collision between Siberia and Tarim
plate in Late Paleozoic. Since Cenozoic, strong compression
caused by the collision between Indian and European plates
has led to intense uplift of pre-Mesozoic terrains in Tianshan
Area. Analysis of growth strata and regional geological studies
show that rapid uplift of the Tianshan in Late Cenozoic
occurred younger than 10-7Ma, of which the existence of
extremely thick Quaternary molasse sediments indicates that
the uplift and denudation in a relatively high tectonic position
occurred younger than 3Ma, paradoxically, most of the
thermochronology data gained from the FT (Fission Track) is
>20Ma [1], lack of data which is <7Ma.
Non-dilution 4He content measurement technique is
developed in the Helix MC multi-collector mass spectrometer
in our laboratory [2], as well as the establishment of the
(U-Th)/He dating experimental procedure. Apatite in
granite、gabbro sampled from Tianshan orogenic belt are
dated by (U-Th)/He method, obtained a series of ages around
5Ma-10Ma, which provide geochronological evidence for a
rapid uplift event in Late Miocene-Pliocene in Tianshan
orogenic belt.
Acknowledgements: This work was supported by the
Science and Technology Research Project of China (No.:
2007CB411306; 200911043-13; 1212011120293)
[1] Hendrix et al. (1994), Geology!22:487-490. [2] Chen
et al. (2010), Mineral Deposit!29(S):821-822.
Mineralogical Magazine
657
Redox evolution of the late
Neoproterozoic to early Cambrian
ocean on Yangtze platform, China
X. CHEN1,2*, D. VANCE2, H.-F. LING1, C. ARCHER2,
G.A. SHIELDS-ZHOU3 AND L.M. OCH3
Department of Earth Sciences, Nanjing University, Nanjing
210093, China (*correspondence: [email protected])
2
Bristol Isotope Group, School of Earth Sciences, University
of Bristol, Bristol BS8 1RJ, UK
3
Department of Earth Sciences, University College London,
London WC1E 6BT, UK
1
The late Neoproterozoic-early Cambrian interval (663-521
Ma) witnessed a critical transition in the surficial Earth
system. Although it is still debated whether physical or
biological factors controlled this transition, the redox state of
the atmosphere and ocean are generally considered to be a key
factor in the cause and effect relationships. Here we present
data for several redox tracers, including Mo isotope
compositions, Fe speciation and Mo/TOC ratios in the
organic-rich shales/carbonates from the Yangtze platform,
Southern China.
The results suggest a key evolutionary transition either
side of ca. 580-551 Ma. Between 663 and 580 Ma, Fe
speciation data give high FeHR/FeT (> 0.38) with relatively low
FePy/FeHR (< 0.7). Both Mo concentrations and Mo/TOC ratios
are low. (98Mo values are not far from the modern dissolved
riverine input value of 0.7. Between ca. 551 and 521 Ma, Fe
speciation begins to show more variation. Unprecedented
enrichment of Mo also emerges as a characteristic of sediment
and the range of (98Mo values show an extended range of
variation.
The data suggest a still low atmosphere O2 level during the
early stage, resulting in low input of Mo and sulfate to the
ocean. Sulfate deficiency and/or low productivity in the ocean
induced ferruginous anoxia. Due to a low proportion of Mo
output via the oxic sink and quantitative removal to sediments,
no obvious fractionation of Mo was recorded. But a
pronounced oxidation event initiated after (at least) ca. 551
Ma. Elevated atmosphere O2 level and sulfate input to the
ocean may have resulted in expansion of euxinic, suboxic, and
oxic environments. Moreover, expansion of the ocean Mo
reservoir also stimulated greater fractionation of Mo in
anoxic/suboxic environments. (98Mo in euxinic sediments
reached the modern value after ca. 530 Ma, marking the
epilogue of this profound redox transition in the ocean, and
coincident with the immediately following peak of metazoan
radiation. This study is supported by NSFC grant 40872025.
www.minersoc.org
658
Goldschmidt Conference Abstracts
Metasomatic pyroxenites and
peridotites in the mantle wedge:
Tracing the high Nb/Ta reservoir
Y. CHEN, K. YE, S. GUO AND J.B. LIU
State Key Laboratory of Lithospheric Evolution, Institute of
Geology and Geopgysics, Chinese Academy of Sciences,
P.O. Box 9825, Beijing 100029, China
(*correspondence: [email protected])
The Nb/Ta ratios in most silicate earth reservoirs are
generally subchondritic (< 19.6±0.6), and thus a ‘hidden’ high
Nb/Ta ratio reservoir is expected in the deep Silicate Earth.
The core of the Earth [1] and the deep recycled eclogites [2]
have been regarded as the candidates of the high Nb/Ta
reservoirs. However, high-pressure experiments demonstrate
that the melts/fluids released from the HP-UHP eclogite
commonly have higher Nb/Ta ratios than the residue rutilebearing eclogites [3-5]. Such melts and fluids with high HFSE
and Nb/Ta ratios are expected to penetrate into the cold mantle
wedge just above the subduction slab and result in significant
metasomatism. However, the Nb/Ta ratios in the metasomatic
cold mantle wedge are still unclear.
A relevant case study is represented by a mafic-ultramafic
complex in Maowu, Dabieshan UHP belt, eastern China. It is
mainly composed of orthopyroxenite and garnet
orthopyroxenite, with minor garnet clinopyroxenite, garnet
websterite, harzburgite and dunite. The Maowu pyroxenites
are formed by interactions of refractory mantle wedge
harzburgite or dunite with slab-derived fluid. Most of these
metasomatic pyroxenites and peridotites contain Ticlinohumite, which is the major Ti-Nb-Ta-bearing mineral in
these rocks. The Ti-clinohumite is formed by the interaction
between protolith olivine and a UHP (~5.5 GPa, 800 oC) slabderived fluid rich in Ti, Nb and Ta. The whole-rock Nb/Ta
ratios in most fresh metasomatic pyroxenites and peridotites
are superchondritic (20-28), however, the unmetasomatic
harzburgite and dunite still have subchondritic Nb/Ta ratios
(13-17). The Nb/Ta ratios in the Ti-clinohumite are similar to
those of the whole rock. The superchondritic Nb/Ta ratios in
the Maowu metasomatic pyroxenites and peridotites indicate
that the cold metasomatic mantle wedge just above the
subduction slab may be the potential “hidden” superchondritic
Nb/Ta reservoir in the Silicate Earth.
[1] Wade & Wood (2001), Nature 409, 75-78. [2] Rudnick et
al. (2000), Science 287, 278-281. [3] Foley et al. (2000), GCA
64, 933-938. [4] Rapp et al. (2003), Nature 425, 605-609.
[5] Schmidt et al. (2004) EPSL 226, 415-432.
Mineralogical Magazine
Metamorphic growth and
recrystallization of zircons in
negative !18O metamorphic rocks:
A combined study of U-Pb dating,
trace elements, and O-Hf isotopes
YI-XIANG CHEN, YONG-FEI ZHENG AND REN-XU CHEN
School of Earth and Space Sciences, University of Science
and Technology of China, Hefei 230026, China
([email protected])
A combined in situ SIMS and LA-(MC)-ICPMS study
incorporating of U-Pb dating, trace elements, O-Hf isotopes
was conducted on zircons from ultrahigh-pressure
metamorphic rocks at Qinglongshan in the Sulu orogen,
China. The results indicate that many zircons are actually
different proportions of mixtures between residual cores and
metamorphic overgrowths, with contrasts in (18O values, U-Pb
ages, Th/U ratios and REE patterns. Generally, residual cores
have U-Pb ages of middle Neoproterozoic, positive (18O
values, high Th/U and 176Lu/177Hf ratios, high REE contents,
and type magmatic REE patterns. They crystallized from
positive (18O magmas in the middle Neoproterozoic. In
contrast, newly grown domains show concordant Triassic UPb ages, negative (18O values, low Th/U and 176Lu/177Hf
ratios, low REE contents, and REE patterns typical of
metamorphic growth. The domains grew from negative (18O
fluids that were produced by metamorphic dehydration of
high-T glacial meltwater altered rocks. The large (18O
variations between grains and intragrain domains indicate
varying degrees of O isotope exchange between the residual
cores and the negative (18O metamorphic fluids. Protolith
magmatic zircons underwent three types of metamorphic
recrystallization, with extents of modification depending on
accessibility of the negative (18O fluids. Solid-state
recrystallization still maintains the positive (18O values and
other features of magmatic zircon except some extent of
lowering in U-Pb ages. Dissolution recrystallization results in
strongly negative (18O values, almost complete resetting of
U-Pb ages and partial redistribution of REE systems.
Replacement recrystallization causes variable negative (18O
values, partial resetting of REE, and the U-Pb and Lu-Hf
isotope systems. Therefore, this combined in situ study not
only places robust constraints on genesis of metamorphic
zircons, but also allows discrimination between the different
types of zircons in eclogite-facies metamorphic rocks.
www.minersoc.org
Goldschmidt Conference Abstracts
Stability of engineered nanoparticles
under various environmental
conditions: Measurements and
modeling
YONGSHENG CHEN, WEN ZHANG, KUNGANG LI
School of Civil and Environmental Engineering, Georgia
Institute of Technology, Atlanta, Georgia, 30332
([email protected])
To better understand and predict the environmental fate of
engineered nanoparticles (ENPs) and their biological effects,
characterization of their aqueous stability (e.g., aggregation
and ion release) is important. In this study, we investigated
and developed models to describe aqueous behaviors of serval
selected ENPs. The ENPs include CeO2, Ag, and quantum
dots (QDs), which have broad commercial applications and
toxicological relevance. The primary physicochemical
properties of ENPs (i.e., morphology, size distribution and
surface potential) were characterized by transmission electron
microscopy (TEM), atomic force microscopy (AFM), dynamic
light scattering (DLS), and zeta potential instrument. The
aqueous stability was evaluated by studying the aggregation
kinetics under different levels of salt, natural organic matter
(NOM) and temperature by time resolved-dynamic light
scattering
(TR-DLS).
Extended
Derjaguin%Landau%
Verwey%Overbeek (EDLVO) theory and the attachment
efficiency (or inverse stability ratio) were both used to
interpret the aggregation mechnisms. Moreover, we developed
models by combining EDLVO with Arrhenius equation or von
Smoluchowski’s population balance equation to describe
aggregation kinetics of ENPs. Particularly, the model derived
from EDLVO and Arrhenius equation was also used to
simulate the Ag+ release kinetics and the influences of particle
size, concentration, dissolved oxygen, and other
environmental factors (e.g., temperature) on ion release
kinetics. Finally, we investigated the oxidative dissolution of
QDs under irradiation of ultravoliet (UV) light at 254 nm..
The effects of irradiation intensity, dissolved oxygen (DO),
temperature, and surface coating on the dissolution kinetics of
QDs were systematically investigated. Our results showed that
the possible mechanism of the oxidative dissolution of QDs
involved the formation of reactive oxidative species (ROS) on
the surface of QDs under UV irradiation, and ROS may
further oxidize the core-shell compositions of QDs and
subsequently release the metal ions (Cd2+, Se2+, and Zn2+). The
knowledge gained from this study proivdes insight
information about aqueous stability of ENPs, which lays out
groundwork toward a better understanding of environmental
impacts of ENPs.
Mineralogical Magazine
659
Quantification non-linear flow and
transport in fractures based on
boundary layer theory and MIM
Z. CHEN, H. N. LI AND R. Z. LI
School of Resources and Environmental Engineering, Hefei
University of Technology, Hefei, 230009, China
([email protected])
Solute transport in fractures or fractured media becomes a
big issue in CO2 geological sequestration, groundwater
reservoir finding, oil exploiting, nuclear waste disposal and
many other fields[1-4]. More and more attentions were drawn
on solute transport in single rough fracture. Among which,
Fickian Law is believed to be the “right” form of governing
law, however, extensive evidences such as “early arrival” and
“the long tail” show non-Fickian transport [5-6].
The roughness of the fracture and the non-linear flow were
considered to be two important reasons for non-Fickian
transport [7]. Application of boundary layer theory in
describing the flow condition in fracture seems to be a choice
in non-Fickian explanation by Qian et al. [8]. A viscous
boundary layer existed near fracture wall and the flow velocity
changed rapidly. A low velocity zone (or zero velocity in
cavities caused by roughness) and a fast velocity zone exist
based on boundary layer theory. As a simplification of the
boundary layer dispersion problem in single rough fracture,
the mobile-immobile (MIM) model may be applicable. MIM
approah assign a mobile domain and a immobile domain for
the transport. The mobile domain was used to approximate the
region near the symmetry of the fracture and the immobile
domain used in low velocity zone.
By fitting the experimental data of solute breakthrough
curve (BTC) through a single rough fracture using MIM we
found that MIM did an excellent work. The early arrival of
peak value can be explained by the dispersion in fast velocity
zone and the long tailing phenomenon can be explained by the
delayed transport in low or zero velocity zone. Further work
can be carried out on finding the relationship between the
thickness of boundary layer and mobile water fraction
coefficient in MIM.
[1] Zhou et al. (2004) Int. J. Rock Mech. Min. Sci. 41:402.
[2] Luo et al.(2006) Geochim.Cosmochim. Acta 70: 376-376.
[3] Qian et al. (2006) Hydrogeol. J. 14: 1192-1205. [4] Qian
et al. (2009) Hydrogeol. J. 17 (7): 1749-1760. [5] Qian et al.
(2005) J. Hydrol. 311: 134-142. [6] Luo et al.(2009)
Geochim.Cosmochim. Acta 73: 802-802. [7] Qian et al.(2007)
J. Hydrol. 339: 206-219. [8] Qian et al. (2011) J. Hydrol. 399:
246-254.
www.minersoc.org
660
Goldschmidt Conference Abstracts
Influence of sedimentary gas bubble
ebullition on interfacial transport in
permeable marine sands
C.H. CHENG AND M. HUETTEL*
Water table fluctuations with soil
temperature changes in a laboratory
experiment
DONG-HUI CHENG
Earth, Ocean, and Atmos. Science Dept., Florida State
University, Tallahassee, FL, USA
(*correspondence: [email protected], [email protected])
School of Environmental Sciences and Engineering, Chang#an
University, Xi#an 710054, China ([email protected])
In the uppermost centimeter of shallow, permeable
sediments, photosynthesis by microalgae causes oxygen
supersaturation, leading to the formation of oxygen bubbles.
Ebullition is one of several processes that affect circulation
and exchange of water into and out of the sediment, yet is not
well understood. It occurs when these gas bubbles are
released due to growth in size or waves and tide-induced
pressure oscillations, and may enhance the release or exchange
of solutes. In sandy, coarse-grained sediments bubbles occur
mostly as small inconspicuous interstitial bubbles, in contrast
to larger formations of free methane gas in deeper layers of
muddy sediments. Laboratory ebullition experiments utilizing
inert dye showed the effects of the sediment depth of
ebullition and the volume of sediment affected by the bubble
flow. Compared to sediment cores, where diffusion was the
sole transport mechanism for the dye, flux in the ebullition
experiments was enhanced 5-23 fold. Analyses of the
sediment cores revealed a distinct pattern of pore water flow
as a result of ebullition, where circulation that was effective in
vertical and horizontal mixing of pore fluids. In field
experiments using bromide as intert tracer, bubble ebullition
caused an enhancement of pore water exchange and thus
benthic pelagic coupling.
A phenomenon of the diurnal water table fluctuations with
soil temperature changes was derived from a laboratory
experiment on soil (eolian sand) evaporation. The water table
rise with the soil temperature increase in daytime and it
declined with the soil temperature decrease in nighttime. In
10-day time scale, the water table also exhibited the same
variations with temperature changes. The influence of
temperature on diurnal water table fluctuation was considered
ignorable and only exhibited in long-term changes in previous
studies [1,2]. However, our experiment results showed it is
notable.
A New Observation about Water Table Fluctuation
Figure 1: Water table fluctuations with soil tempeture
changes
Discussions of Results
In our experiment, the groundwater evaporation was not
effect on the water level due to the depth to water table (about
1.1 m) was much less than the extinction depth of water
evaporation in the eolian sand media ( about 0.5 m), as well as
the barometric pressure change. Traditionally the water table
fluctuations due to temperature changes were interpreted using
the Muskat equation [3,4]. However, it only reasonable to
explain the water tables rise due to temperature rise. The
Influence of temperature on the soil capillary pressure of soi is
probably main factor for water table fluctuation. a completely
discussion of these results will be presented in the conference.
[1] Loheide (2005) Water Resour. Res. 41, W07030
doi:10.1029/2005WR003942. [2] Hare et al. (1997) Ground
Water 35, 667-671. [3] Constantz (1994) Water Resour. Res.
30, 3253-3264D. [4] Meyer (1960) J. Geo. Res 65, 1747-1752
.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
661
Erosion rate of yellow soil on pine hill
in the Three Gorges reservior region
using 137Cs Technique
Alteration of biochemical pools
assemblage induced in A. variabilis by
TiO2 nanomaterials exposure
Chongqing Key Laboratory of Exogenic Minerallization and
Mine Environment, Chongqing Institute of Geology and
Mineral Resources, Chongqing 400042, China
(*correspondence: [email protected])
2
Chongqing Research Center of State Key Laboratory of Coal
Resources and Safe Mining 400042, China
Dept. of Civil and Environmental Enginering, Northeastern
University, Boston, MA 02115
(*correspondence: [email protected])
J. CHENG 1,2, Y. SHUANG1,2*, Z.Y. JIANG1,2 AND H. LI1,2
1
Soil erosion and degradation, as one of the major
environmental problems man is confronted with, is becoming
a hot spot in the study of soil and environmental Science. In
recent years, radio-isotope tracer in soil erosion studies has
become one of the hottest research topics in the field of soil
Science. This research presents the 137Cs tracer in the soil
erosion rates in the Three Gorge Reservoir Region in
Chongqing.
Two yellow soil profile samples which formed by the
weathering of quartz sandstone of the Upper Triassic Xujiahe
Fm were collected from the pine hill. Simplified mass balance
model established by Zhang et al [1] is applied to
overestimate the soil erosion rates.137Cs of Section A (sits on
upper section of the hill, with an incline of about 15 degrees )
is mainly gathered in middle section (4-10cm). The 137Cs
inventories of the section is estimated to be 1099.8 Bq/m2. The
soil erosion rate on this section is 1009.92 t/km2.a, in
concordance with the result of Dong et al (2006)[2].
As to section B (sits on middle to lower section of the hill,
with an incline of about 15 degrees), 137Cs is mainly gathered
in surface soil (2-6cm). The 137Cs inventories and soil erosion
rate values are 2139.8 Bq/m2 and -190.937 t/km2.a
respectively, indicating slight accumulation happened before.
Combined with some previous results[2], it may be
deduced that the soil erosion rates of this area might have little
relationship to the soil type and soil forming rocks, but were
greatly affected by topography, soil utilization way and
vegetation.
This research project was financially supported by the
Argo-geologic Survey in Zhong county Project from
Chongqing Administration of Land, Resources and Housing.
C. CHERCHI AND A.Z. GU*
In this study Fourier Transformed Infrared spectroscopy
and Transmission Electron Microscopy were used to evaluate
the ecotoxic impact of TiO2 nanomaterials to the cellular
reorganization of macromolecules in the nitrogen-fixing
cyanobacteria A. variabilis. The increase in occurrence and
intracellular levels of cyanophycin grana proteins (CGPs,
Figure 1) reveal changes in the dynamics of cellular nitrogen
storage and metabolism. The results also showed characteristic
temporal re-allocation patterns after short and long-term
exposure of the predominant chemical markers (lipids, nucleic
acids, carbohydrates and proteins) with nTiO2 dose-dependent
trends.
Figure 1: CGPs formation after cell exposure to nTiO2 (right)
compared to control (left).
In conclusion, this study reveals important insights into
the metabolic strategies implemented by cyanobacteria under
nTiO2 exposure and anticipates at larger scale the impact on
important biogeochemical processes, such as nitrogen cycle,
and ecological food web dynamics.
[1] Zhang et al. (1990) Hydro. Sci. 35, 243-252. [2] Dong et
al. (2006) J. Soil and Water Conserv. 20, 1-5.
Mineralogical Magazine
www.minersoc.org
662
Goldschmidt Conference Abstracts
Natural water contamination under
chromite deposit mining
E.V. CHERKASOVA AND B.N. RYZHENKO
Vernadsky Institute of Geochemistry and Analytical
Chemistry RAS, Moscow, Russia ([email protected])
For any chromite mining site there is a problem of ore
waste burial. In our opinion for Aganozerskoe deposit (Russia,
Kareliy) there are two possibilities for waste burial: to keep
waste wet with water on the land surface or to put it in the
nearest water reservoir (pool, lake). According to [1] the main
factors which determine dissolution of minerals and migration
of aqueous species are the following: (a) weight ratio of rock
to water (R/W), (b) partial pressure of O2 and ,-2 in the site
atmosphere, (c) chemical and mineralogical compositions of
the site rock, (d) temperature-pressure conditions of the waterrock system under study. Using these conclusions and
computer simulation technique of water-rock systems the
chemical reactions which are occurred between the rock
minerals and water have been modeled to estimate the
groundwater contamination.
The computer model of water - serpentinised ultramafic
rock - atmosphere system that has been constructed is based
on groundwater and rock chemical compositions of
Aganozeskoe deposit. The system under consideration consists
of H-O-Si-Al-Ca-Mg-Na-K-Ti-P-Mn-Cl-S-C-Cr-Zn-Ni-Co-V.
The simulation code is HCh [2, 3]. The modeling shows that
keeping waste wet on the land surface under the atmosphere
oxygen access to the chromite ore and ore waste stores will
result in chromite oxidation and aqueous chromium species
migration in environment. The burial of ore waste in water
pool decreases the influence of oxidizing dissolution of
chromite. But it is necessary to keep the pool water isolated
from landscape lakes. According to [4] the rate of oxidizing
dissolution of chromite might be experimentally measured.
[1] !"#$%&' (.)., )*+,%-& ../., 0',1 2.3 ..: /0120,
2004. [2] 0'#"&' 4.2. 34567879. 1999. : 6. ,. 646-652.
[3] 0'#"&' 4.2. 34567879. 2008. : 8. ,. 890-897. [4] Oze
C.J.-P. Ph.D.Thesis. Stanford University. 2003
Lead isotope composition variations
in sulfides from hydrothermal fields
of the Mid-Atlantic Ridge:
High-precision MC-ICP-MS
isotope data
I.V. CHERNYSHEV, N.S. BORTNIKOV AND
A.V. CHUGAEV1
IGEM RAS, Moscow, Russia ([email protected])
The high-precision MC-ICP-MS method of Pb-isotope
analysis (±0.03%) with mass-bias correction to 205Tl/203Tl
isotope ratio [1, 2 and others] have been applied for study of
sulfides from 4 hydrothermal fields (HFs) in the southern part
(12°58'–16°38' N) of Mid-Atlantic Ridge (MAR) spreading
zone: Ashadze, Semenov, Logachev, and Krasnov.
Sulfide Pb-isotope ratios variation scale in the four studied
HFs have been estimated: 0.04–0.09% for 206Pb/204Pb, 0.02–
0.04% for 207Pb/204Pb, and 0.04–0.07% for 208Pb/204Pb, while
analytical error was ±0.03%. These variations are lower by a
factor of 3–4 than was evident from the data previously
obtained for HFs in MAR and Pacific Ocean by traditional
TIMS, which are characterized by precision ±0.1-0.2%. Using
high-precision MC-ICP-MS method we did not reveal
dependence of the Pb-isotope composition on the type of HFs
sulfide mineral and total Pb concentration in it.
The results provide the following regularities [3]. (1) At
small (close to 0.03%) variations of the Pb-isotope
composition of sulfides from individual HF, the latter differ
significantly from each other by all isotope ratios. (2) Sulfides
of HFs related to serpentinized peridotites have more
radiogenic Pb-isotope composition by all isotopes (206Pb,
207
Pb, and 208Pb) in comparison to HFs occurring on tholeiitic
basalts. (3) On the evolutionary Pb-Pb isotope diagrams the
Pb-isotope compositions of HFs sulfides discretely plot in the
area of MAR basalts and are located exactly along the NHRL.
The Pb-isotope characteristics of sulfides from MAR HFs
permit participation of two mantle sources of Pb (DMM and
HIMU) in their formation with prevalence of the first of them.
Sulfides of MAR HFs are similar to MORB by the total range
of the Pb-isotope composition; because of this, the data
obtained do not contradict the idea that hydrothermal solutions
and then sulfides inherit the Pb-isotope composition from
underlying rock series. As above represented data show
convective cells provide exceptional homogenization of Pb
isotope composition for individual HFs.
[1] Rehkamper, Halliday (1998) Intern. J. Mass Spec. Ion
Proc 58, 123–133. [2] Chernyshev et al. (2007) Geochem. Int.
45, 1065-1076. [3] Chernyshev et al. (2011) Doklady Earth
Sciences 437, 507–512.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
U-Pb and Th-Pb dating of apatite by
LA-ICPMS
Aqueous CO2 solutions at silica
surfaces and confined environments
DAVID M. CHEW1*, PAUL J. SYLVESTER2
2
AND MIKE N. TUBRETT
Department of Geology, Trinity College Dublin, Dublin 2,
Ireland. (correspondance*: [email protected])
2
Department of Earth Sciences and Inco Innovation Centre,
Memorial University, St. John’s, Newfoundland, A1B
3X5 Canada ([email protected], [email protected])
1
Apatite is a common U- and Th-bearing accessory mineral
in igneous, sedimentary and metamorphic rocks and ore
systems. However, low U, Th and radiogenic Pb
concentrations, elevated common Pb and the lack of a U-ThPb apatite standard remain significant challenges in dating
apatite by LA-ICPMS.
This study has determined U-Pb and Th-Pb ages for seven
apatite occurrences (Durango, Emerald Lake, Kovdor,
Mineville, Mudtank, Otter Lake and Slyudyanka) by LAICPMS [1]. Analytical procedures involved rastering a 10!m
spot over a 40*40!m square to a depth of 10!m using a
Geolas 193nm ArF excimer laser coupled to a Thermo
ElementXR single-collector ICPMS. These raster conditions
minimized laser-induced inter-element fractionation which
was corrected for using the back-calculated intercept of the
time-resolved signal. A Tl–U–Bi–Np tracer solution was
aspirated with the sample into the plasma to correct for
instrument mass bias. External standards (Ple;ovice and
91500 zircon, NIST SRM 610 and 612 silicate glasses and
STDP5 phosphate glass) along with Kovdor apatite were
analysed to monitor U-Pb, Th-Pb and Pb-Pb ratios.
Common Pb correction employed the 207Pb method, and
also a 208Pb correction method for samples with low Th/U.
The 207Pb and 208Pb corrections employed either the initial Pb
isotopic composition where known or the Stacey and Kramers
model. No 204Pb correction was undertaken because of 204Pb
interference by 204Hg in the argon gas supply.
Age calculations used a weighted average of the common
Pb-corrected ages and Tera-Wasserburg Concordia intercept
age (both unanchored and anchored through common Pb).
The samples yield ages consistent with independent estimates
of the U-Pb apatite age, which demonstrates the suitability of
the analytical protocol employed. Weighted mean age
uncertainties are as low as 1-2% for U- and/or Th-rich
Palaeozoic-Neoproterozoic samples [1].
[1] Chew et al. (2011) Chem. Geol. 280, 200–216.
Mineralogical Magazine
663
ARIEL A. CHIALVO1, LUKAS VLCEK1 AND
DAVID R. COLE2
Oak Ridge National Laboratory, Oak Ridge, TN 37631,
U.S.A. ([email protected])
2
Ohio State University, Columbus, OH 43210, U.S.A.
1
The CO2 capture and sequestration in geological reservoirs
have been considered as a potential approach to mitigate its
release into the atmosphere and reduce its contribution to the
greenhouse effect on climate change. The feasibility and
safety of this process for long-term storage of CO2 depends on
the low hydraulic permeability of the caprock and its ability to
hold the aqueous fluid in its porous structure, i.e., its
interfacial and confinement properties.
Interfacial and confined fluids exhibit microstructural,
dynamical, and thermophysical behavior that differ
dramatically from their bulk counterparts. The immediate
consequence is the inherent inability of current modeling
approaches to capture the actual (aqueous-caprock) fluid-solid
and fluid-fluid interfacial mechanisms underlying the
geological CO2 sequestration.
Here we present a molecular-based study of the
microstructural and dynamical behavior of CO2-aqueous
solutions at silica surfaces and under extreme confinement, to
address fundamental issues, including (a) how the degree of
surface hydrophobicity affects the interfacial structure, (b)
how the overlapping of interfacial structures affects the
confined fluid composition (relative solubility), and (c) how to
account for the effect of medium polarization on the species
solubilities.
Toward those goals we developed (i) a synergistic
approach to calibrate the CO2-H2O interactions for the
accurate and simultaneous prediction of the compositions of
the two phases in liquid (water_rich)-liquid (CO2_rich)
equilibrium at realistic well conditions [1]; and (ii) we applied
a molecular dynamics protocol that allows the simultaneous
study of the behavior of the aqueous system at interfaces and
within confinement between silica surfaces, while the fluid
remains in equilibrium with its own bulk at isobaricisothermal conditions.
[1] L. Vlcek, et al., “Optimized Unlike-pair Interactions for
Water-Carbon Dioxide Mixtures described by the SPC/E and
EPM2 Models” Journals of Physical Chemistry B. In press
Acknowledgements. Support for this work comes from
the US Department of Energy through the LBNL “Center for
Nanoscale Control of Geologic CO2” (FWP ERKCC67) under
contract DE-AC05-00OR22725 to Oak Ridge National
Laboratory, managed and operated by UT-Battelle, LLC.
www.minersoc.org
Goldschmidt Conference Abstracts
664
Carbon-isotope and Mercury
Stratigraphies of the Frecheirinha
Formation cap carbonate,
Northeastern Brazil
L. CHIGLINO , A.SIAL AND C. GAUCHER
1
1
3
NEG-LABISE, Departamento de Geologia, Universidade
Federal de Pernambuco, Recife, Brazil ([email protected],
[email protected])
2
Facultad de Ciencias, Universidad de La República,
Montevideo, Uruguay ([email protected])
1
The Frecheirinha Formation is a carbonate unit of the
Ubajara Group in the the Middle Coreaú Domain, state of
Ceará, Brazil. This formation is composed of basal marls
followed by limestone-dolostones rhythmites and by
stromatolitic limestone in the top. It overlies red to purple
slates and, locally, itabirites of the Caiçaras Formation. The Cisotope pathway for the Frecheirinha Formation with negative
(13C~-6 ‰values in the base and positive values up to 3.7 ‰
in the top of the formation is compatible with pathways for
cap carbonates elsewhere. On the contrary to other studied cap
carbonates in northeastern Brazil (e.g. Sergipano and Seridó
Belts and Rio Pardo Basin), no (13C value > + 3.7‰ has been
recorded in the Frecheirinha Formation, and this raises the
possibility of an Ediacaran age for this carbonate sequence. A
preliminary Hg survey with carbonate samples from the
Freicherinha Formation was carried out, aiming to use Hg as a
proxy of volcanism intensity and CO2 buildup during a
possible snowball event. Typically, Hg contents have been
analyzed only form basal marls and that show negative (13C
values ~ -6‰. In this way, only carbonates deposited at the
earliest stages of the aftermath of glacial events were
analyzed. The highest mercury contents were over 10 times
higher than background values (<1nng-1).This suggest that
CO2 in the basal portion of this carbonate formation is mostly
mantle-derived, transferred to the atmosphere by volcanism.
The only age available for the Frecheirinha Formation (0.61
Ga) is based on poor Rb-Sr isochron for clay fractions of the
Caiçara Formation [1]. The Mucambo pluton intruded these
carbonates at 0.54 Ga [2]. These carbonates show 87Sr/86Sr
values ~ 0.7075 which do not allow an unambiguous age
assignment. Similar Sr-isotope values and associated itabirites
without glacial features occur in the Ediacaran Arroyo del
Soldado Group of Uruguay.
Compound-specific stable isotope
analysis of amino acids as a novel tool
for ecological food web study
Y. CHIKARAISHI, N.O. OGAWA, Y. TAKANO,
M. TSUCHIYA AND N. OHKOUCHI
Institute of Biogeosciences, Japan Agency for Marine-Earth
Science and Technology ([email protected])
Knowledge of the trophic position (TP) of organisms in
food webs allows understanding of biomass flow and trophic
linkages in complex networks of ecosystems. Compoundspecific stable isotope analysis (CSIA) of amino acids is a
novel method with that enables TP estimates of organisms in
food webs [1-4]. This approach is based on contrasting
isotopic fractionation during metabolic processes between two
common amino acids: glutamic acid (Glu) shows significant
15
N-enrichment of +8.0‰ during reactions (transamination,
deamination) that cleaves the carbon-nitrogen bond, whereas
phenylalanine (Phe) shows little change in (15N values (by
+0.4‰) during conversion to tyrosine that neither forms nor
cleaves the carbon-nitrogen bond [3]. In the previous studies
[3,4] we established based a number of natural and laboratory
grown organisms a general equation for estimating the TP of
organisms by CSIA of amino acids:
TP = [((15NGlu – (15NPhe + <)/7.6 ] + 1
where < represents the isotopic difference between Glu and
Phe in primary producers (–3.4‰ for aquatic cyanobacteria
and algae, +8.4‰ for terrestrial C3, and –0.4‰ for terrestrial
C4 plants). In the presentation, we briefly review this amino
acid method and then show its application to various natural
organisms in aquatic marine and freshwater as well as
terrestrial food webs.
[1] McClelland & Montoya (2002) Ecology 83, 2173-2180.
[2] Popp et al. (2007) In Stable isotopes as indicators of
ecological change. Academic Press. pp 173-190.
[3] Chikaraishi et al. (2009) Limnol. Oceanogr.: Meth 7, 740750. [4] Chikaraishi et al. (2010) In Earth, Life, and Isotopes.
Kyoto University press. pp. 37-51.
[1] Sial et al. (2003). IX Brazilian Geochemical Congress.
Belém, Pará: 410-411. [2] Sial et al. (2000), Annals of the
Braz. Academy of Science, 72: 539-558.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Self-assembly in natural organic
matter: Lipid and amphiphilic
components
G. CHILOM, J. SHORE AND J. A. RICE *
Dept. Chemistry & Biochemistrry, South Dakota State
University, Brookings, SD 57007, USA
([email protected], [email protected],
*correspondence: [email protected])
Recent work has demonstrated that natural organic matter
(NOM) in soils and sediments has a hierarchical or “structure
within a structure” architecture [1,2]. The first-order structure
results from the self-assembly of amphiphilic and lipid
components to form a nanostructured composite material. The
second-order structure is formed by the self-assembly of this
composite with additional but nonamphiphilic components.
The objective of this study is to investigate the dependence of
NOM self-assembly on the concentration and nature of
components in the first-order level of organization, which is
assumed to initiate and control the final NOM structure.
Composite materials isolated from four different
environmental samples were analyzed by differential scanning
calorimetry and multidimensional solid-state NMR
spectroscopy. Variation of the excess heat capacity and the
mobility and domain structures of composite materials with
their composition was used to assess structural organization of
these materials.
[1] Chilom & Rice (2009) Langmuir 25, 9012-9015. [2]
Chilom et al. (2009) Org. Geochem. 40, 455-460.
Mineralogical Magazine
665
Emplacement of passive margin
sediments into deep crustal hot zones
of continental arcs: Interplay of
tectonic and magmatic thickening in
the formation of continental crust
E. J. CHIN1, C.-T. LEE1, D. L. TOLLSTRUP2, L.-W. XIE2,
J. B. WIMPENNY2 AND Q.-Z. YIN2
1
2
Rice University, Houston, TX USA ([email protected])
University of California, Davis, CA, USA
Both magmatic and tectonic processes cause thickening of
continental arc lithosphere. In western USA, increased
Farallon-North American plate convergence during the
Cretaceous was accompanied by lithospheric thickening due to
enhanced magmatism and tectonic shortening. Here, we use
lower crustal metaquartzite (80% SiO2) xenoliths in late
Miocene basalts in the central Sierra Nevada Batholith,
California to constrain how arc lithosphere thickens and
matures. The xenoliths are equigranular in texture and contain
>50% qtz, ~10% gt, <40% pl, trace TiO2, Al2SiO5, and biot.
High qtz mode, abundant detrital zircons, and oriented
graphites suggest a supracrustal sedimentary protolith.
However, last equilibration T using TitaniQ are 700-800°C.
Thermodynamic modelling shows that coexistence of gt and pl
for these bulk compositions limits equilibration P’s to 0.6-1.6
GPa with GASP barometer giving 0.9-1.3 GPa. These P-T
constraints indicate equilibration of the metaquartzites within
a hot lower crust (18-45 km). All zircons have discordant
U-Pb with variable upper intercept ages (1.7, 2.7, 3.3 Ga;
consistent with Hf model ages) and common lower intercept
age (100 Ma). Collectively, the above indicate that protoliths
of the metaquartzites were Proterozoic to Paleozoic passive
margin sediments of N. American affinity and that they were
transported to lower crustal depths at ~100 Ma during the peak
of Cretaceous arc magmatism. Underthrusting of N. American
lithosphere beneath the arc could have transported these
sediments to high P, but underthrusting alone cannot explain
the xenoliths’ high final temperatures. An extra heat source,
imparted by deep lithosphere magmatic “hot” zones, is
needed. Our results thus suggest a complex interplay between
tectonics and magmatism that drives vertical growth and
compositional evolution of continental arcs. Despite the
common view that magmatic differentiation drives lower crust
to become mafic and upper crust felsic, underthrusting can
introduce felsic rocks into lower crust. Local density,
rheologic and seismic inversions are thus expected.
www.minersoc.org
666
Goldschmidt Conference Abstracts
Multi-decadal change of atmospheric
aerosols and their effect on surface
radiation
Oxygen optodes as fast sensors for
eddy correlation measurements in
aquatic systems
MIAN CHIN1*, THOMAS DIEHL1,2, DAVID STREETS3,
MARTIN WILD4, YUN QIAN5, HONGBIN YU1,6,
QIAN TAN1,2, HUISHENG BIAN1,2 AND WEIGUO WANG7
NASA Goddard Space Flight Center, Greenbelt, Maryland,
20771, USA (*correspondence: [email protected])
2
University of Maryland Baltimore County, Baltimore,
Maryland, USA
3
Argonne National Laboratory, Chicago, Illinois, USA
4
ETH, Zurich, Switzerland
5
Pacific Northwest National Laboratory, Redland,
Washington, USA
6
University of Maryland College Park, College Park,
Maryland, USA
7
NOAA NCEP, Camp Springs, Maryland, USA
1
We present an investigation on multi-decadal changes of
atmospheric aerosols and their effects on surface radiation
using a global chemistry transport model along with the nearterm to long-term data records. We focus on a 28-year time
period of satellite era from 1980 to 2007, during which a suite
of aerosol data from satellite observations, ground-based
measurements, and intensive field experiments have become
available. We analyze the long-term global and regional
aerosol trends and their relationship to the changes of aerosol
and precursor emissions and assess the role aerosols play in
the multi-decadal change of solar radiation reaching the
surface (known as “dimming” or “brightening”) at different
regions of the world, including the major anthropogenic
source regions (North America, Europe, Asia) that have been
experiencing considerable changes of emissions, dust and
biomass burning regions that have large interannual
variabilities, downwind regions that are directly affected by
the changes in the source area, and remote regions that are
considered to representing “background” conditions.
Mineralogical Magazine
LINDSAY CHIPMAN1, MARKUS HUETTEL1*,
PETER BERG2, VOLKER MEYER3, INGO KLIMANT4,
RONNIE GLUD5,6 AND FRANK WENZHOEFER3,7
Department of Earth, Ocean, and Atmospheric Science,
Florida State Univ., Tallahassee, FL 32303, USA
([email protected], *correspondence: [email protected])
2
Department of Environmental Science, University of
Virginia, Charlottesville, VA, USA ([email protected])
3
Max Plank Institute for Marine Microbiology, Bremen,
Germany ([email protected],
[email protected])
4
Graz University of Technology, Graz, Austria
([email protected])
5
Institue of Biology, University of Southern Denmark,
Odense, Denmark ([email protected])
6
Scottish Association for Marine Science, Dunstaffnage
Marine Laboratory, PA37 1QA, Dunbeg, Scotland
7
HGF MPG Research Group Deep Sea Ecology and
Technology, AWI-Bremerhaven, Germany
1
The aquatic eddy-correlation technique can be used to
non-invasively determine the oxygen flux across the sedimentwater interface by analyzing the covariance of vertical flow
and oxygen concentration in a small measuring volume above
the seabed. The method requires fast sensors that can follow
the rapid changes in flow and the oxygen transported by this
flow. In this paper, we demonstrate the suitability of fast
optical oxygen sensors (optodes), in place of the traditionally
used electrodes. Optodes have the advantage over electrodes
of being less susceptible to signal drift, more durable under
field conditions, less expensive, and repairable. Comparisons
of the response times of optodes and electrodes to rapid
oxygen changes showed that the optimized optodes had a
slightly longer response time (164 ± 70 ms) than the
microelectrodes (151 ± 60 ms) but were fast enough to capture
the oxygen fluctuations that are relevant for the eddy
correlation flux calculations. Side by side comparisons of
benthic oxygen fluxes collected with both electrode-based and
optode-based eddy correlation instruments in freshwater and
marine environments showed good agreement between the
measured fluxes. Over a 4 h mid-day measuring period, short
term (15min) oxygen fluxes in the spring-fed Wakulla River
(Florida) fluctuated between 52 and 401 mmol m-2 d-1 (average
165 ± 67 mmol m-2 d-1), revealing the importance of local light
and flow variations on the benthic oxygen exchange.
www.minersoc.org
Goldschmidt Conference Abstracts
Oxidation of FeS by Fe3+(aq)
P. CHIRITA * AND M.L. SCHLEGEL
1
2
University of Craiova, Calea Bucuresti 107I, Craiova
Romania (*correspondence: [email protected])
2
CEA, DEN/DANS/DPC/SCP/Laboratory for the Reactivity of
Surfaces and Interfaces, F-91191 Gif-sur-Yvette, France
([email protected])
1
The oxidative dissolution of iron monosulfides (FeS)
releases toxic elements, such as heavy metals and arsenic, in
natural solutions [1]. Also, partial oxidation of sulfur from FeS
minerals produces sulfur-bearing compounds which may alter
the redox properties of natural media [2]. Hence, it is
important to understand the reactions between FeS minerals
and oxidative solutions.
In this work we examine the kinetics and mechanism of
oxidative dissolution of synthetic FeS in presence of Fe3+(aq) by
monitoring the pH, Eh and total dissolved Fe concentration
([Fe]total) of oxidant solutions during their contact with FeS
that lasted 4 hours. Note that concentrations of dissolved
sulfur were too low to be reliably quantified. The experiments
were performed in acidic media (2=pH=3), 25 oC and [Fe3+(aq)]
spanning the [10-4; 10-3] mol L-1 range.
The experimental data indicate that Fe3+ was removed
from the solution at pH>2. A progressive increase in pH
values and an Eh decrease within 4 h of reaction time were
also observed. The reaction order of FeS oxidation with
respect to [H+] is estimated to 0.65 at initial pH 3.0, and
increases up to 1.0, when initial pH decreases [3], indicating
that [H+] is an important parameter of FeS oxidation. In
contrast, ferric iron concentration has only a small effect on
FeS oxidative dissolution rate in studied [Fe3+(aq)] range.
Taking into consideration present findings it can be stated
that mechanism of FeS oxidation starts with the protonation of
mineral surface [2]. Thereafter, the adsorbed protons
accelerate Fe2+ release [3]. Finally, Fe3+(aq) may adsorb at the
surface and oxidize the sulfur moieties to insoluble species,
presumable polysulfide (Sn2-(s)) and elementar sulfur (S0(s)).
The authors greatly appreciate support from IFA-CEA
Program (Project C1-04).
Two competing processes in
petrogenesis of basaltic magma
conduits
SOFYA CHISTYAKOVA* AND RAIS LATYPOV
Department of Geosciences, University of Oulu, Oulu, FI90014, Finland
(*correspondence: [email protected])
A recent geochemical study of dolerite dykes from many
regions of the world has revealed that small dolerite dykes
(<50 cm wide) representing shallow parts of basaltic magma
conduits are remarkably zoned [1-5]. The zonation is
compositionally anomalous since compatible and incompatible
components behave in a manner inconsistent with predictions
of fractional crystallization of basaltic magma. Here we put
forward a novel concept interpreting the anomalous
compositional trends in dolerite dykes as a result of
competition between two petrogenetic processes with opposite
effects on dyke composition. These are (a) the filling of dykes
with magmas that become increasing more evolved with time
and (b) in situ cumulate growth of these inflowing magmas
against dyke sidewalls. The first process makes inwardsolidifying rocks geochemically more evolved whereas the
second process more primitive. The combined operation of
these two competing processes results in intricate chemical
profiles of dykes. Geochemical modelling indicates that all the
observed patterns in distribution of compatible and
incompatible elements in small dolerite dykes can be
reproduced by variations in the relative contribution of these
two petrogenetic processes. One important implication of this
study is that compositional zonation of small dolerite dykes is
indicative of an effective magma fractionation along sidewalls
of the deeper parts of basaltic magma conduits.
[1] Chistyakova & Latypov (2009a) Geol. Mag. 146, 485-496.
[2] Chistyakova & Latypov (2009b) Lithos 112, 382-396.
[3] Chistyakova & Latypov (2010) Geol. Mag. 147, 1-12.
[4] Chistyakova & Latypov (2011a) (Ed.) Srivastava, Keys for
Geodynamic Interpretation, p. 569-581. [5] Chistyakova &
Latypov (2011b) (Ed.) Srivastava, Keys for Geodynamic
Interpretation, p. 583-601.
[1] Thomas et al. (1998) Geochim. Cosmochim. Acta 62 15551565. [2] Chirita et al. (2008) J. Colloid Interface Sci. 321,
84–95. [3] Chirita and Descostes (2006) J. Colloid Interface
Sci. 299 260-269.
Mineralogical Magazine
667
www.minersoc.org
668
Goldschmidt Conference Abstracts
Zircon U-Pb and Hf isotopic
constraints on the magmatic and
tectonic evolution in Iran
HAN-YI CHIU1*, SUN-LIN CHUNG1, MOHAMMAD H.
ZARRINKOUB2, I-JHEN LIN1, HSIAO-MING YANG1,
CHING-HUA LO1, HAO-YANG LEE1,
KWAN-NANG PANG1, SEYYED S. MOHAMMADI2 AND
MOHAMMAD M. KHATIB2
Department of Geosciences, National Taiwan University,
Taipei, Taiwan (*correspondence: [email protected],
[email protected])
2
Department of Geology, Birjand University, Birjand, Iran
1
This study reports new zircon LA-ICPMS U-Pb ages and
Hf isotope compositions, coupled with whole-rock Ar-Ar age
data and geochemical analyses, for magmatic rocks of
Cenozoic age from the Urumieh-Dokhtar magmatic arc
(UDMA) in Iran. The UDMA has been divided into three parts
by latitude of ~35°N and ~31°N in this study. The
northwestern UDMA show two distinct age periods: (1) the
older period of 53-27 Ma exhibits zircon #Hf(T) values from
+11.8 to +1.8; and (2) the younger period of <11 Ma exhibits
zircon #Hf(T) values from +12.8 to +5.9 and reveals the same
formation time as the collision-related volcanism in eastern
Anatolia proposed by Keskin [1]. The central and southeastern
parts of UDMA yield ages of 51-16 Ma with zircon #Hf(T)
values from +12.8 to -1.3 and ages of 45-5 Ma with zircon
#Hf(T) values from +15.7 to +1.1, respectively. The overall
zircon #Hf(T) values implicate that at least three significant
episodes of mantle input occurred in the middle Eocene (~40
Ma), the early Oligocene (~30 Ma) and the late Miocene (~10
Ma). Zircons from the youngest magmatic rocks in central
UDMA, however, show much negative #Hf(T) values from
+8.1 to -1.1, suggesting contamination of crustal materials has
played an important role in the middle Miocene magmatism in
this region. Furthermore, the pre-collisional, calc-alkaline
magmatism in the UDMA appears to cease southeastward, that
implies the diachronous collision occurred between Arabia
and Eurasia and started in Armenia and northwestern Iran.
[1] Keskin (2007) Geol. Soc. Amer. Spec. Paper 430, 693722.
Mineralogical Magazine
Optimization of a low-background
liquid scintillation counter for the
determination of 222Rn and Uranium
isotope in ground water
S.Y. CHO, K.Y. LEE, Y.Y. YOON AND K.S. KO
KIGAM, Daejeon 305-350, Korea ([email protected],
[email protected], [email protected],
[email protected])
An analytical method for the measurement of the 222Rn
and Uranium isotope in water sample by liquid scintillation
counting technique using LKB Wallac Quantulus 1220 liquid
scintillation counter(LSC) equipped with pulse shape
analyzer(PSA). We have optimized the pulse-discrimination
capabilities of the detector to achieve the best >/< separation
and the lowest detection limits possible. LSC was calibrated
using the optimization of PSA with 241Am and 90Sr/90Y as well
as 226Ra. The optimum PSA level for the measurement of 222Rn
was 100 when measuring a sample containing 8 ml water and
12 ml of Optiphase HiSafeTM 3 scintillation cocktail. By the
analysis of 226Ra standard, 222Rn counting efficiency and
precision were found to be 91.6 ± 3.6% and 2%, respectively.
Detection limits of 222Rn for 5 hours counting were counted to
be 0.11 Bq/L.
A solvent extraction method was used for the
measurement of uranium isotope in ground water samples.
The effect of solution volume was not significant, the error
being less than 5% for solutions ranged from 100 to 1000 mL
at pH 2. The uranium extraction efficiency was found to be the
maximum at pH 2 while the pH was varied from 0.5 to 10. We
dispersed 20 mL of liquid scintillation for both solvent
extraction and alpha/beta discrimination in one liter of water at
pH 2. The extraction efficiency of uranium isotopes was near
96% according to the NIST standard. Using the method, the
lower detection limit for uranium was determined to be 0.018
Bq/L, with the counting time of 300 min. The results of this
study were also compared to those obtained by the
conventional ICP-MS measurement. It is demonstrated that
the suggested method is valuable to determine the optimum
extraction and measurement conditions for uranium in ground
water
The analytical method obtained from this work was also
applied to the determination of 222Rn and uranium isotopes in
some ground water samples.
www.minersoc.org
Goldschmidt Conference Abstracts
Hydrothermal copper mineralization
in the Gyeongnam mineralized
district, Korea
SANG-HOON CHOI
Chungbuk National Univ., Cheongju, Chungbuk, 361-763
Korea ([email protected])
Copper mineralization in the Gyeongnam district, which is
located within the Cretaceous Gyeongsang basin, mainly
occurs in hydrothermal polymetallic quartz and/or carbonate
veins. These veins are all related to the Cretaceous Chindong
granite. Generally, successive polymetallic ore mineralization
in the district shows a simplified mineralogy progressing
through: Fe-W-Mo, Cu, (Cu-)Zn-Pb with sulfosalts, and/or
ferric mineralization. The early Gyeongnam hydrothermal
system is characterized by high-salinity brine and/or CO2-rich
fluids. The vein mineralization initiated at high temperature
('550!) from fluids with high salinity (up to about 60 equiv.
wt. % NaCl or NaCl+KCl) derived mainly from the granite
source and/or CO2-rich fluid by fluid unmixing coupled with
boiling. The oxygen isotope data ($18Owater = 8.9 to 4.7‰ for
the early mineralization) suggest that early hydrothermal
fluids in the Gyeongnam hydrothermal system likely represent
magmatic and/or meteoric water whose isotopic composition
was controlled by exchange with a large volume of igneous
(and metamorphic or sedimentary) rocks at near-magmatic
temperatures. In the waning portion of the vein mineralization,
the high-temperature, high-salinity fluids gave way to
progressively cooler, more dilute fluids (down to '150! and
'1 equiv. wt. % NaCl). There is a systematic decrease in
calculated $18Owater values with decreasing temperature in the
Gyeongnam hydrothermal system (from 5.0 to -9.9 ‰). These
trends are interpreted to indicate progressive mixing of highsalinity, magmatic hydrothermal fluids with cooler and less
saline meteoric groundwater. Equilibrium thermodynamic data
combined with mineral paragenesis, and fiuid inclusion and
isotope data indicate that copper minerals precipitated mainly
within a temperature range of 350° to 250°C. During early
copper mineralization at 350°C, significant amounts of copper
(103 to 102 ppm) could be dissolved in weakly acid NaCl
solutions. For late mineralization at 250°C, about 100 to 10–1
ppm copper could be dissolved. Equilibrium thermodynamic
interpretation indicates that the copper in the Gyeongnam
hydrothermal system could have been transported mainly as a
chloride complex and the copper precipitation occurred as a
result of cooling accompanied by changes in the geochemical
environments (ƒs2, ƒo2, pH, etc.) resulting in decrease of
solubility of copper chloride complexes.
Mineralogical Magazine
669
Mineralogy and Geochemistry of the
Yangyang IOA deposit, South Korea
SEON-GYU CHOI1*, JIEUN SEO1, JUNG-WOO PARK2 ,
DONG WOO KIM1
1
Department of Earth and Environmental Sciences, Korea
University, Seoul 136-701, Korea
(*correspondence: [email protected],
[email protected], [email protected])
2
Research School of Earth Sciences, Australian National
University, Canberra ACT 0200, Australia
([email protected])
The Yangyang deposit is characterized by the
occurrence of a distinctive type of iron oxide apatite (IOA)
deposit such as a Kiruna-type deposit. Occurrence in iron
mineralization is concordant to discordant layered, lenticular
or massive, magnetite-biotite, magnetite-actinolite, and
magnetite-apatite-biotite-pyrite ores, which are hosted by a
stratum of metamorphosed subvolcanic-sedimentary unit
enclosed within Paleoproterozoic gneiss complexes. The
phosphorous content in the apatite-rich magnetite ore varies
up to ca. 7.38 wt. % P2O5. However, the iron ores have about
40 to 90 wt. % Fe2O3 with significantly low titanium content
(< 0.57 wt. % TiO2) and V content (< 404 ppm V).
The dominant mineral constituents consist of magnetite,
actinolite, biotite and fluorapatite with subordinate amounts of
scapolite, albite, diopsidic pyroxene, pyrite and carbonates.
Titanite, allanite, monazite and fluorite are distinctively found
in a mineral accessory assemblage. Apatite grains contain Thpoor monazite, magnetite, and sulfide inclusions commonly,
and exhibit patchy zoning in concentrations of REE and some
trace elements such as Si, S, V, Zr, Y, Pb, Th, and U,
suggesting that apatite undergoes hydrothermal overprint as
observed in other IOA deposits of Kiruna area, Sweden, and
Bafq district, Iran. Sulfides clearly overprint the oxide stage
assemblages and consist of minor pyrite ± chaclcopyrite. Low
Ti, V, Cr, Co and Ni contents in magnetite indicate that these
magnetites are not magmatic origin (i.e., nelsonite). The
halite-bearing fluid inclusion in apatite shows an evolving
hydrothermal system from saline fluids. REE-rich fluorapatite
and titanite in the Yangyang ore mean ages of 198±13 Ma and
226.1±5.3 Ma, respectively (U-Pb LA-ICPMS ages). The
Yangyang iron deposit has been precipitated from iron oxidevolatile-rich magmatic-hydrothermal fluids, which is derived
from slightly alkaline magma.
www.minersoc.org
670
Goldschmidt Conference Abstracts
Lu-Hf and Sm-Nd isotope systematics
of Korean spinel peridotites:
A case for Nd-Hf decoupling
SUNG HI CHOI1,* AND SAMUEL B. MUKASA2
Department of Geology and Earth Environmental Sciences,
Chungnam National University, Daejeon 305-764, S.
Korea (*correspondence: [email protected])
2
Department of Earth Sciences, University of New Hampshire,
Durham, NH 03824 ([email protected])
Kinetics and mechanism of antigorite
dehydration: Implications for
subduction zone seismicity
M. CHOLLET1, I. DANIEL1, K. T. KOGA2, G. MORARD 3
1
AND B. VAN DE MOORTÈLE
1
We have determined the Hf and Nd isotopic compositions
of spinel peridotite xenoliths in alkali basalts from
Baengnyeong (BR) and Jeju (JJ) islands, South Korea, in order
to constrain the timing of melt depletion events. Equilibration
temperatures estimated by two pyroxene thermometry range
from 780 to 950oC, and 960 to 1010oC for BR and JJ
peridotites, respectively. The BR peridotite clinopyroxenes are
characterized by extremely radiogenic Hf in association with
isotopically less extreme Nd, resulting in strong Nd-Hf
decoupling compared to the mantle array. This is in stark
contrast to the observation of well-correlated isotopic
compositions of Hf and Nd in the JJ peridotite clinopyroxenes,
plotting along the Nd-Hf mantle array. The Hf abundances and
isotopic compositions of the BR clinopyroxenes were less
affected by relatively recent secondary enrichments that
overprinted the LREE abundances and Nd isotopes, which
caused decoupling of Nd-Hf isotopes. In the case of JJ
peridotites, the Nd-Hf isotopic compositions are considered to
have been re-equilibrated, probably because of efficient
diffusion at relatively higher temperature than the BR
peridotites.
Lu-Hf tie lines for clinopyroxene and orthopyroxene from
four of the Korean peridotites have negative slopes on the LuHf isochron diagram, yielding negative ages. This is
interpreted as indicating recent isotopic exchange of
orthopyroxene by reaction with metasomatic agents having
low 176Hf/177Hf components. Secondary overprinting in
orthopyroxene was facilitated by the fact that this mineral has
considerably lower Hf concentrations than does the co-located
clinopyroxene. BR lherzolite clinopyroxenes yield a Lu-Hf
isochron age of 1.9 ± 0.1 Ga, which is independently
supported by a model Os age (TRD) of 1.8 Ga on a refractory
BR peridotite. We interpret this age range to mark the time of
stabilization of the mantle section beneath this area by major
melt extraction. This Proterozoic melt removal coincided in
time with widespread ca. 2.1 to 1.8 Ga tectonothermal events
documented throughout the Korean peninsula.
Mineralogical Magazine
Université Lyon 1, ENS de Lyon, CNRS, UMR 5276,
Laboratoire de Géologie de Lyon, France
([email protected])
2
Laboratoire Magmas et Volcans, UMR CNRS 6524, IRD –
M163, Université Blaise Pascal Clermont-Ferrand, France
3
MARUM, Center for Marine Environmental Sciences,
Bremen, Germany
3
Institut de Minéralogie et de Physique des Milieux
Condensés, Paris, France
1
Properties of serpentine minerals are thought to influence
the occurrence and location of intermediate-depth seismicity
in subduction zones, which is often characterized by two
dipping planes separated by ca. 30 km defining a double
seismic zone. The seismicity of the lower plane is believed to
be provoked by the dehydration of serpentine since the
experimentally determined stability limit for antigorite
matches hypocenters location. This requires that the fluid
produced by dehydration is released much faster than the
typical time-scale of ductile deformation mechanisms. Here
we measured the kinetics of antigorite dehydration in situ at
high pressure and high temperature by time resolved
synchrotron X-ray diffraction in a closed system. Antigorite
dehydrates in two steps. During step (1) it partially breaks
down into olivine and a hydrous phyllosilicate closely related
to the 10Å phase. The modal abundance of the intermediate
assemblage is described by 66 wt% antigorite, 19 wt% olivine,
12 wt% 10Å phase. During step (2) at higher temperature, the
remaining antigorite and the 10Å phase fully dehydrate. From
the analysis of reaction progress data, we determined that the
major release of aqueous fluid occurs during step (2) at a fast
rate of 10-4 m3fluid.m-3rock.s-1. This exceeds by orders of
magnitude the typical time scale of deformation by ductile
mechanisms of any mineral or rock in the subducting slab or
in the overlying mantle wedge. These results suggest that the
fast dehydration of antigorite may well trigger the seismicity
at intermediate depth in subduction zones.
[1] Chollet et al. (2011) Journal of Geophysical Research,
116, B04203.
www.minersoc.org
Goldschmidt Conference Abstracts
Distribution characteristics of Pt, Pd,
and related traffic elements in dusts
from Seoul, Korea
Geologic carbon-sulfur
co-sequestration: Experimental
investigation of a natural analogue,
Madison Limestone,
SW Wyoming USA
H.T. CHON1*, M. SAGER2 AND H.Y.LEE3
Department of Energy Resources Engineering, Seoul
National University, Seoul 151-744, Korea
(*correspondence: [email protected])
2
Austrian Agency for Health and Food Safety, A-1226 Vienna,
Austria
3
Korea Institute of Geosciences and Mineral Resources,
Daejeon 305-350, Korea
1
The emission level and pollution characteristics of
platinum (Pt) in dust, soils, and tree barks collected from
Seoul metropolitan city was published for the first time in
Korea (Lee and Chon, 2006). The previous study confirmed
that an important source of Pt in roadside environment is
automobile catalytic converter, and that it indicates a tendency
to increase Pt levels in road dusts along with traffic volume.
The study also suggested that not only traffic volume but also
driving style have a great influence on Pt levels in road dusts.
In this study previous dust samples and some new
collected dusts from Seoul were reanalyzed to determine Pt,
Pd, and some traffic metal elements by ICP-MS and ICP-OES.
The concentration levels of Pt and Pd were in the range of 0 –
444 (median 76) ng/g and 172 – 1,215 (median 609) ng/g,
respectively, and remarkably high concentration of Pd and Pt
in dust was found in the heavy traffic areas . Palladium also
shows similar distribution trend with Pt that remarkably high
concentration of Pd and Pt in dust was found in the heavy
traffic areas. Distribution trend of some traffic elements such
as Pb, Cr, Cu, Ni, Mo, Bi is also similar to that of Pt showing
relatively high correlations (higher than r = 0.50) with Pt and
Pd. Road dusts with high Pt and Pd levels were enriched in
traffic related elements compared with road dusts from control
suburb areas.
Mineralogical Magazine
671
C. CHOPPING1 AND J. KASZUBA1,2
Department of Geology and Geophysics, University of
Wyoming, Laramie, Wyoming 82071, USA
([email protected], [email protected])
2
School of Energy Recources, University of Wyoming,
Laramie, Wyoming 82071, USA
1
SO2 is a common impurity in effluent gasses of coal-fired
power plants. Co-sequestering SO2 and CO2 can eliminate the
need for pure CO2 separations and related parasitic energy
costs. For 50 million years, the Mississippian Madison
Limestone in SW Wyoming has naturally contained a mixture
of CO2 (66%-95%), H2S (5%) and other gases as well as sulfur
complexes (SO42- and HS-) and minerals (anhydrite, pyrite,
and native sulfur). These products of SO2 disproportionation
provide the opportunity to evaluate how a carbon-sulfur cosequestration scenario evolves.
Hydrothermal experiments performed at 250 bars, 110°C
evaluated brine-rock±supercritical CO2 reactions between a
Na-Cl-SO42- brine (I=0.52 mol/Kg, 80 mmol/Kg SO42-) and
two different synthetic rock types (Do-Cc-Anh-Py and Do-CcPy). After CO2 injection, dissolved CO2 concentrations
increased from 1.0 mmol/Kg to 1.1 mol/Kg. In situ pH
decreased from approximately 7.5 to 4.8. Ca2+ and Mg2+
concentrations initially increased, but subsequent anhydrite
precipitation decreased Ca2+ and SO42- concentrations in both
experiments. Fe2+ and Mn2+ metal mobilization increased from
below detectable limits to 0.06 mmol/Kg in both experiments.
Calcite dissolution, as evidenced by mineral pitting and
etching, and anhydrite mineralization in the experiments are
consistent with petrologic observations of Madison Limestone
core. Ca2+ from dissolving calcite and dolomite reacts with
SO42- provided by SO2 disproportionation to precipitate
anhydrite. Anhydrite precipitation provides a mineral trap for
sulfur, but may also clog available pore space.
www.minersoc.org
Goldschmidt Conference Abstracts
672
Bio-inorganic interfaces
in the critical zone
Geochemical position of Pb, Zn and
Cd in soils near a mine/smelter:
Effects of land use, type of
contamination and distance from
pollution source
J. CHOROVER
Department of Soil, Water and Environmental Science,
University of Arizona, Tucson, AZ 85721
([email protected])
At the particle scale, critical zone biogeochemical
interfaces are heterogeneous and patchy. Patchiness results
from the wide range in mutual affinities among primary biogeo-chemical components that are continuously influent to
terrestrial weathering systems (water, minerals, solutes, gases,
cells). In addition, hydrologic events shift the disequilibrium
state, generating short time-scale surface reactions, colloidal
dynamics, and biotic/abiotic transformations that are
superimposed on (and constrained by) long-term weathering
history. A corollary is that the structure and reactivity of bioinorganic interfaces are a function of the sequence of
perturbations acting on the porous medium over an integrated
soil residence time.
The complexity of critical zone systems raises challenging
research questions that highlight the need to unravel these
couplings and feedbacks:
What products form when
biochemical and geochemical components react in pore
waters?
How stable are these products to further
biogeochemical transformation and how do they influence the
evolution of interfacial structure in particles, aggregates, and
porous media? How does this “architecture” dictate surface
reactions and the bioaccessibility of carbon and/or
contaminants? How does interfacial reactivity change over
time and environment to control larger system (e.g.,
catchment) response?
These questions can be addressed by combining tools of
analytical biogeochemistry with those of hydrology,
geomorphology and ecology in bench-, meso- and field-scale
experiments. One goal is to elucidate molecular- and porescale components and processes that are active contributors to
observed meso- and field-scale phenomena (e.g., metalloid
stabilization, carbon sequestration, catena structure formation,
catchment hydrochemical response). Such studies require
multi-faceted, interdisciplinary measurements in common
systems and locations. Examples are presented from ongoing
studies conducted at three scales (1) biomolecule-mineral
surface reactions in aqueous suspensions, (2) metal(loid)
transformation in phytostabilized tailings mesocosms, and (3)
biogeochemical weathering fluxes in semi-arid catchments of
the southwestern US.
Mineralogical Magazine
VLADISLAV CHRASTN?1, [email protected] VANAK2, MICHAEL
KOMÁREK3 AND MARTIN NOVÁK1,
Czech Geological Survey, Geologická 6, 152 00 Praha 5,
Czech Republic
2
Department of Soil Science and Soil Protection, Czech
University of Life Sciences Prague, KamBcká 129,
165 21 Praha 6, Czech Republic
3
Department of Agro-Environmental Chemistry and Plant
Nutrition, Czech University of Life Sciences Prague,
KamBcká 129, 165 21 Praha 6, Czech Republic
1
Contaminated agriculture and forest soil samples with
mining and smelting related pollutants were collected in the
Pb-Zn-Ag mining area near Olkusz, Upper Silesia to (i)
compare the chemical speciation of metals in meadow and
forest soils situated at the same distance from the point source
of pollution (paired sampling design), (ii) to evaluate the
relationship between the distance from the polluter and the
retention of the metals in the soil, and (iii) to assess the effect
of deposited fly ash vs. dumped mining/smelting waste on the
mobility of metals in the soil. The smelting emissions
intensively contaminated mainly the upper soil horizons, while
the deposition of processing waste resulted in a contamination
of the deeper parts of soil profiles. The maximum
concentrations of Pb, Zn and Cd were detected in a forest soil
profile near the smelter and reached about 25 g kg-1, 20 g kg-1
and 200 mg kg-1 for Pb, Zn and Cd, respectively. Forest soils
are much more affected than agriculture soils. However
agriculture soils suffer from the downward metal migration
more than the forest soils. Metal mobility ranges in the studied
forest soils are as follows: Pb>Zn'Cd for relatively circumneutral soil pH (near the smelter), Cd>Zn>Pb for acidic soils
(further from the smelter). The mobilization of Pb, Zn and Cd
in soils depends on the persistence of the metal-containing
particles in the atmosphere, and consequently on the
mineralogical transformation controlled by the soil pH. Under
relatively comparable pH conditions, the main soil properties
influencing metal migration are total organic carbon (TOC)
and cation exchange capacity (CEC).
www.minersoc.org
Goldschmidt Conference Abstracts
Multi-isotopic constraints on
contamination history, contaminant
migration and structure of the
F-Area acidic plume, Savannah River
Site
JOHN N. CHRISTENSEN1*, MILES E. DENHAM2,
MARK E. CONRAD1, MARKUS BILL1 AND JIAMIN WAN1
Lawrence Berkely National Lab., Berkeley, CA, USA
(*correspondance: [email protected])
([email protected]; [email protected]; [email protected])
2
Savannah River Natl. Lab., Aiken, SC, USA
([email protected])
1
Seepage basins in the F-Area of the Savannah River Site
were used from 1955 to 1989 for the disposal of low-level
radioactive acidic (ave. pH ~2.9) waste solutions from site
operations involving irradiated uranium and other materials
used in the production of radionuclides. These disposal
activities resulted in a persistent acidic groundwater plume
(pH as low as 3.2) beneath the F-Area including contaminants
such as 3H, HNO3, 90Sr, 129I and U that has impinged on
surface water about 600 m from the basins. After cessation of
disposal in 1989, the basins were capped in 1991. Since then,
remediation consisted of a pump-and-treat system that was
recently replaced by in situ treatment using a funnel-and-gate
system with injection of alkaline solutions to neutralize pH.
In order to delineate the history of contamination and the
current mobility and fate of contaminants in F-Area
groundwater, we have undertaken a study of variations in the
isotopic compositions of U (234U/238U, 235U/238U, 236U/238U), Sr
(87Sr/86Sr), Nd (143Nd/144Nd) water (#18O, #D) and nitrate
(#15N, #18O) within the contaminant plume. The chemical and
isotopic variations in the plume all delineate upper (0-15ft
below water table) and lower (15-35 ft) zones within the upper
aquifer. Together, the data suggest that the lower zone
represents the effects of seepage from the basins during
operation, while the upper zone represents mostly meteoric
water contaminated by infiltration through the sub-basin
vadose zone since closure/capping. Through U isotopic
analysis, we have been able to detect recent migration as the
plume expands laterally, with the greatest extent of U
contamination near the top of the aquifer but decreasing with
depth.
Comparing the U isotopic compositions of
groundwater samples collected within the plume two years
apart tracks the migration of U from up-gradient portions of
the plume. Nd isotopic compositions indicate that REE
concentrations were controlled by progressive interaction
between acid solutions and natural trace minerals in the
sediments. Nitrate has an isotopic signature of processed
waste, but no sign of nitrate bioreduction within the plume.
Mineralogical Magazine
673
Vertical distribution of 236U in the
western equatorial Atlantic Ocean
M. CHRISTL1*, J. LACHNER1, C. VOCKENHUBER1,
M. RUTGERS V. D. LOEFF2, O. LECHTENFELD2
2
AND I. STIMAC
Laboratory of Ion Beam Physics, ETH-Zurich, Switzerland,
(*correspondence: [email protected])
2
Alfred Wegener Institute, 27570 Bremerhaven, Germany
1
During the Pelagia Geotraces cruise PE321 in summer
2010 two depth profiles of 236U were sampled in the western
equatorial Atlantic Ocean (WEA) and subsequently analyzed
at ETH Zurich using low energy accelerator mass
spectrometry (AMS). These data represent the first 236Umeasurements in the open Atlantic Ocean.
236
U is almost exclusively produced by neutron capture on
235
U. While the natural background of 236U/238U is estimated to
be in the 10-12 - 10-14 range anthropogenic 236U/238U ratios are
much higher. For example, it can be estimated that as a
consequence of the atmospheric nuclear bomb explosions
about 1-2 tons of 236U were blown into the atmosphere. Mixed
with the upper few hundred meters of the Ocean this would
result in 236U/238U ratios in the 10-9 range. Although the
expected signal dynamics of 236U/238U in the environment is
very large, currently only AMS-systems have the capability
for a fast and quasi background free detection of 236U/238U
ratios significantly below 10-9.
At stations 39 and 40 of the PE321 cruise two depth
profiles were sampled for 236U (25 m. 2500 m, and 4250 m).
The 236U/238U ratios decrease from about 10-9 at the surface
down to about 10-10 in the Antarctic Bottom Water (AABW).
The advective contribution of anthropogenic 236U from the
North Sea (from nuclear reprocessing plants) seems unlikely
at this location. The most likely explanation for the elevated
ratios in the AABW is the transport and the subsequent release
of particle bound 236U from the biologically active surface
waters. Extrapolating from the calculated 236U-inventories a
total input of 1.5 - 2 tons of 236U can be estimated for the
global fallout. The inventory calculations are consistent with
global fallout as the sole source for 236U at the WEA.
However, simple box model results show that very high Uexport rates from the surface layer to the deep sea (>50 ng cm2
yr-1) would be necessary to reproduce the measured
concentration profile.
Furthermore, a close correlation of salinity and 236U was
found, which is much steeper than the relation with natural Uisotopes in the open ocean. This indicates that, in contrast to
natural U, 236U has not yet reached steady state. Our results
indicate that 236U might have a large potential as a new
conservative and transient tracer in Oceanography.
www.minersoc.org
Goldschmidt Conference Abstracts
674
Sr isotopes (## 88/86Sr and 87Sr/86Sr) in
cold seep environment of Niger and
Nile Delta Fans
NAN-CHIN CHU*1, EMMANUEL PONZEVERA1,
EMMANUEL FAVREAU1, GERMAIN BAYON1 AND
YVES FOUQUET1
1
IFREMER, BP70, Plouzané, 29280, France
(*correspondence: [email protected];
[email protected]; [email protected];
[email protected])
In cold seep areas, carbonates form as a result of the
anaerobic oxidation of methane, which increases alkalinity in
pore waters. Upon formation, cold seep carbonates incorporate
dissolved alkali earth elements, such as Ca and Sr. The Ca
and Sr isotopic compositions of authigenic carbonates and
associated pore waters can hence provide information into
fluid sources and biogeochemical processes at cold seeps.
Over the last decades, radiogenic 87Sr/86Sr ratios in sediment
interstitial fluids have been used for identifying deep fluid
sources in seepage areas. However, recent studies have
demonstrated that significant fractionation of stable Sr
isotopes can occur in marine carbonates, which led to a
revisited view of the oceanic budget [1].
Here, we report paired 87Sr/86Sr and #88/86Sr values on a
series of authigenic carbonate crusts and associated pore
waters from fluid seepage areas of the Niger and Nile deep-sea
fans. Sr isotopes were measured on a Neptune MC-ICP-MS
using Zr for mass bias correction to acquire simutaneously
radiogenic and stable (87Sr/86Sr and #88/86Sr) values [2, 3]. Our
results indicate that #88/86Sr values for most carbonate samples
exhibit very small fractionation relative to seawater or pore
water signatures, contrary to biogenic carbonates that shows a
0.1‰/amu lower than seawater [1]. Exceptions are found for a
few samples collected from mud volcano settings, which are
characterized by distinctively low 87Sr/86Sr and #88/86Sr values.
We will discuss the Sr isotope systematics in comparison with
other proxies.
[1] Krabbenhöft (2010) GCA, 74, 4097-4109. [2] Ohno and
Hirata (2007) Anal. Sci., 23, 1275-1280. [3] Yang et al. (2008)
JAAS, 23, 1269-1274.
What role did methane seeps play in
the formation of the Doushantuo cap
carbonate?
XUELEI CHU1*, JING HUANG2 AND T.W. LYONS3
Institute of Geology and Geophysics, CAS, Beijing 100029,
China (*Correspondance: [email protected])
2
Institute of Geology and Geophysics, CAS, Beijing 100029,
China ([email protected])
3
Dept. of Earth Sciences, Univ. of California, Riverside, CA
92521, USA ([email protected])
1
Extremely negative !13Ccarb values, less than -3‰, have
been reported for the cap carbonate of the Ediacaran
Doushantuo Formation (ca. 635 Ma) and used to support the
hypothesis that methane hydrate destabilization contributed
significantly to formation of the enigmatic cap carbonate and
negative carbon isotope anomalies following Neoproterozoic
ice ages (1, 2). Here, we show distinct differences between the
methane-related carbonate and bulk cap carbonate.
Negative 513Ccarb values of <-3‰ obtained from
isopachous cements and recrystallized carbonate crusts have
been found only in the Yangtze Gorges area (YGA), South
China. These microsamples were reported from secondary,
pore-filling carbonate minerals tied to methane seep activity,
rather than reflecting the bulk composition of the cap
carbonate. We investigated the Doushantuo cap carbonate at
three localities, the Jiulongwan (inner-shelf, YGA), Zhongling
(outer-shelf), and Long’e (basin) sections, and find that the
513C and 518O values for the cap vary from -2‰ to -10‰ and
-5‰ to -12‰, respectively, and show a postive 513C-518O
correlation, with a negative trend from the shallow to deep
sites. Interestingly, all the microsampled 513C and 518O data
from the methane-seep sections in the YGA (1, 2) show two
distinct trends in the 513C-518O cross-plot, a positive
correlation the same as the bulk cap carbonate and negative
correlation attributed to methane oxidation. Similar to the
Upper-Cretaceous Tepee Buttes in Colorado (3), the latter
shows a nice relationship from early to late diagenetic
carbonate phases – starting with very light, methanedominated carbon.
We conclude that the methane-related carbonate can be
distinguished clearly from the bulk Doushantuo cap carbonate
by coupled C and O isotopes.
This research is funded by the Ministry of Science and
Technology of China (Grant 2011CB808805)
[1] Jiang et al. (2003) Nature 426, 822-826. [2] Wang et al.
(2008) Geology 36, 347-350. [3] Kauffman et al. (1996)
Geology 24, 799-802.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Multi-scale modelling of ions and
water diffusion in clays
Two step up-scaling of molecular
diffusion coefficients in clays
S.V. CHURAKOV
Paul, Scherrer Institute, Villigen-PSI, CH-5232, Switzerland
([email protected])
Materials with low hydraulic permeability such as clays
are major components in engineered and natural barriers for
waste disposal sites. Migration of ions and water through such
barrier systems over safety relevant times are predicted
solving diffusion equation on continuum scale. Natural clay,
however are highly heterogeneous in terms of porosity and
mineralogical composition. These heterogeneities are
manifested at different scales and consequently have strong
influence on diffusion of solutes. To fully understand the
mechanism of ion transport in clays the solute migration has to
be addressed using complementary simulations and
measurements capable of resolving the transport and chemical
phenomena on different scales.
In clays, up to 50-70% of fluid accessible pore space is
attributed to the interlayer and the diffuse double-layer
porosity where solution properties, namely the mobility of
ions and water, are strongly influenced by mineral surfaces.
The transport through such nanopores is readily addressed by
molecular simulations. At the sub-micrometer scale the
individual interlayers are interconnected thought the
macrospores. Molecular simulations with explicit solvent
approach are not feasible at this scale anymore. Instead pore
scale stochastic approaches are used to assess the influence of
pore geometry and topology on the effective diffusion
coefficient of the sample. Finally, state-of-the-art X-ray
tomography measurements can provide 3D mineral
distribution in a sample non-destructively at a resolution down
to few micrometers. These data are directly used in transport
simulations to reveal the consequences of mineralogical and
textural heterogeneities in clays and their influence on the
effective transport parameters of clay samples. Such a multiscale treatment of transport phenomena using complementary
modelling and measurement techniques is a necessary
condition for accurate and reliable prediction of radionuclides
migration over geological space and time domains.
Mineralogical Magazine
675
S.V. CHURAKOV1*, TH. GIMMI1,2 AND M TYAGI1
Paul, Scherrer Institute, CH-5232 Villigen-PSI, Switzerland
(*correspondence: [email protected])
2
University of Bern, CH-3012 Bern, Switzerland
1
Mass transport in rocks with low hydraulic conductivity
such as clays originates from Brownian motion of molecules
and ions in the solution and their interaction with the surface
of the minerals. Up-scaling these molecular phenomena to the
continuum scale, which is required for large-scale and longtime predictions, is particularly challenging because the
considered scales differ by orders of magnitude. To address
the up-scaling problem we developed a two-step simulation
approach which enables us to derive macroscopic diffusion
coefficients of water and ions for continuum equations from
pore scale molecular diffusion coefficients [1]. Our starting
point for the up-scaling procedure is local pore diffusion
coefficients derived from molecular dynamics simulations for
specific local environments, such as the interlayer or edge
regions of clay particles. We then assign these local diffusion
coefficients to different types of porosity of a model clay
structure and obtain the structure-averaged effective diffusion
coefficient of the sample by random walk simulations. Our
model clay rock is composed of compacted grains of clay
minerals. The space between the grain boundaries forms
micro-pores. To generate such structures, a kinetic Monte
Carlo method is employed on a grid to obtain closely packed
grains of desired shapes, sizes and orientations. By varying the
composition and geometrical properties of the clay model we
have investigated the effects of mineralogical heterogeneities
and of anion exclusion on the diffusion coefficients measured
in laboratory experiments. Our up-scaling concept is general
and can be used for up-scaling molecular diffusion
coefficients for porous materials with almost arbitrarily
complex structures.
[1] Churakov & Gimmi, (2011) J. Phys. Chem. C 115, 67036714.
www.minersoc.org
Goldschmidt Conference Abstracts
676
Geochemical study Soltanieh
Formation limestone deposits to
determine the primary mineralogy
and the mineralogical processes of
limestone (SW Urmia)
ALIASGHAR CIABEGHODSI
Urmia University-Faculty of Sciences-Department of
Geology-Po.Box:57153-165 Urmia-Iran
([email protected])
Soltanieh Formation deposits in the south west of Urmia
mainly carbonate rocks and shale alternation is made.
Soltanieh Formation calcareous rocks mainly influenced
meteoric diagenetic an open system are located. According to
the distribution main and secondary elements and isotopes of
oxygen and carbon range of calcareous deposits formation
Soltanieh comparable Gordon Limestone of Tasmania with the
mercenaries and the mineralogical composition is aragonite.
Mineralogical
composition
of
aragonite
limestone
Neoproterozoic other parts of the world already has been
confirmed by other researchers [1]. These studies indicate that
the limestone, such as Gordon Limestone of Tasmania,
Meteoric affected processes are located. Soltanieh Formation
limestone samples of oxygen and carbon isotope values are
light to light? 13 °C (mean (-4.57 ‰ VPDB Soltanieh
formation in the samples due to the severe effect is diagenesis
meteoric. Changes in Sr/Mn indicates high dissolution rate
This is limestone. temperature of the limestone formation
based on the heaviest isotope of oxygen (equivalent to ‰
83/5-) and? w sea water (equivalent to 1 ± 3 -), respectively 23
and 31 °C has been calculated.
[1] Fairchild & Spiro (1987) Sedimentology 34, 973-989.
Mineralogical Magazine
Europium structural role in silicate
glasses
M.R. CICCONI1*, G. GIULI1, E. PARIS1, W. ERTELINGRISCH2, D.B. DINGWELL2 AND P. ULMER3
School of Science and Technology – Geology Division,
University of Camerino, I
(*correspondence: [email protected])
2
Dept. of Earth and Environmental Sci., LMU München, D
3
Institut f. Mineralogie und Petrographie, ETH Zürich, CH
1
Rare Earth Elements (REE) have demonstrated to be
important geochemical indicators; in fact, the distribution of
REE in igneous rocks are frequently used to constrain the
mineralogy of the source materials, the degree to which
magma composition has been modified by crystal
fractionation, and to identify the mineral phases removed from
the magma during differentiation. Moreover, the Eu redox
ratio can be used to constrain the formation conditions within
a very large range of oxygen fugacity down to few log units
below the Fe/FeO buffer. The Eu+2/(Eu+2 + Eu+3) ratio is
therefore very useful in the study of meteoritic material and in
studying planetary evolution. A complete understanding of
transition and REE elements is important for the geochemical
and petrological interpretations of magmatic processes and
partition properties between melt and crystals. To this aim,
synthetic silicate glasses corresponding to compositions
relevant for the Earth sciences were used to study the
dependence of the redox states of Eu on the bulk melt
composition and at different values of oxygen fugacity (from
air to IW-2). The samples have been analyzed via Eu LIIIedge X-ray Absorption Spectroscopy (XAS) to study the Eu
oxidation states and local environments. Eu LIII-edge XANES
peak analysis allowed the quantitative assessment of Eu redox
ratio. XANES spectra vary systematically with composition
and with fO2 (log fO2 ! 0 to –11.6) indicating changes in the Eu
oxidation state. The intensity of the shoulders on the
absorption edges were quantified and used to determine
Eu+2/(Eu+2 + Eu+3) ratio. Moreover, the local environment of
Eu was determined by EXAFS (Extended X-ray Absorption
Fine Structure) analyses, highlighting the different Eu
behaviour as function of the fO2. This work has clearly
demonstrated that for a better interpretation of the Eu
anomalies observed in rocks and minerals, which are often
used to constrain magmatic evolutions of igneous regions, the
melt composition and the redox condition must be taken into
consideration.
www.minersoc.org
Goldschmidt Conference Abstracts
Nanoparticles in aqueous
environments: Electrochemical,
nanogravimetric, STM and AFM
studies
I. CIGLENECKI1*, E. BURA-NAKID1, M. [email protected],
I. MILANOVID1, N. BATINA2, A. AVALOS-PEREZ2 AND
D. KRZNARID1
RuEer Bo;koviF Institute, BijeniGka 54, 10 000 Zagreb,
Croatia (*correspondence: [email protected])
2
Laboratorio de Nanotecnología e Ingeniería Molecular, Área
de Electroquímica, Depto. Qiumica, UAM-I, Mexico City,
Mexico.
1
Electrochemical and piezo-nanogravimetric (EQCM)
studies in combination with atomic force and scanning
tunneling microscopy (AFM,STM) have been used for
characterization and determination of chalcogenide
nanoparticles in model solutions and natural samples.
Different electrode surfaces (Hg and Au) were used to give
more details relating to attachment, adsorption, deposition and
interaction between selected nanoparticles and functionalized
electrode surfaces.
Mercury electrodes preconcentrate some metal sulfide
nanoparticles effectively, enabling their detection at
submicromolar concentrations. Voltammetrically active metal
sulfides are accumulated on Hg electrode surfaces by two
mechanisms: a) adsorption of nanoparticles to an electrode
where they undergo reduction at -0.9 to -1.35 V (vs.
Ag/AgCl), and b) formation directly at the Hg electrode
surface in supersaturated metal sulfide solutions; the latter
produces an analytical artifact [1]. In the case of FeS
nanoparticles, anodic oxidation of Hg by FeS at around -0.45
V is the operating mechanism for their determination in
aqueous solution [2].
By following changes in resonance frequency
accompanied with some changes in current produced during
oxido-reduction processes, it is possible to characterize
physico-chemical properties and to calculate the mass of
nanoparticles deposited on the Au surface over a broad range
of environmentaly relevant solution characteristics, including
variation in ionic strength, composition and particle sizes.
Particle deposition mechanisms are studied in relation to
variations of particle charge, particle size and applied
electrode potential, all with the aim to improve and develop
new analytical methods for fast, selective, qualitative and
quantitative nanoparticle characterization in natural waters.
This research was suported by UKF grant 62/10.
The largest deposit of strategic REE,
Bayan Obo, geological situation and
environmental hazards
HANA CIHLAROVA1, JINDRICH KYNICKY1, XU CHENG2,
WENLEI SONG2, ANTON CHAKMOURADIAN3 AND
KATARINA REGUIR3
Mendel University in Brno, 613 00 Brno, Czech Republic;
([email protected])
2
Chinese academy of sciences, China
([email protected])
3
University of Manitoba, Winnipeg, Manitoba, Canada
([email protected])
1
Bayan Obo Fe-Nb-REE super large deposit in Inner
Mongolia is the main source of REE in the world and makes
China the monopolist producer of these strategic elements. A
typical feature of the Bayan Obo super large deposit is the
presence of polymetalic Fe-Nb-REE mineralization in 3
different ores - disseminated, banded and massive. The
principal
REE
bearing
minerals
are
bastnaesite
[(Ce,La,Nd)(CO3)F] followed by monazite [(Ce,La,Nd)PO4] in
disseminated and banded ores. Magnetite and hematite are the
dominant Fe-ore minerals in massive ores. Mining process in
grassland and ore processing in Baotou bring several
environmental hazards. Actual risk assessment is
contaminated dust by Th and heavy metals, and itHs
transporting by sand storms to X00 km in main direction to SE
(Peking capital). Leaching of old-mined ore is responsible for
contamination of soil and ground water collectors by heavy
metals and radioactive thorium (bastnaesite and monazite ores
contain up to 0,5% ThO2). The harm to environment of the
past is mainly ore processing causing dominantly water
contamination. Presently the ore processing is ecologically
and economically well-developed under supervision of Baotou
Institute of rare earth elements.
[1] Bura-NakiF et al. (2007), Anal. Chim. Acta 594, 44-51. [2]
Bura-NakiF et al. (2011), Electroanalysis, in press.
Mineralogical Magazine
677
www.minersoc.org
678
Goldschmidt Conference Abstracts
Structural aspects and surface
reactivity of aluminous ferrihydrite
precipitates
A.C. CISMASU 1* F.M. MICHEL1,2 J.F. STEBBINS1,
C.M. LEVARD1 AND G.E. BROWN JR1,2.
Re-partitioning of Fe and Cu during
the oxidation and acidification of acid
sulfate soil materials
S.R. CLAFF1,2*, E.D. BURTON1, L.A. SULLIVAN1 AND
R.T. BUSH1
1
Dept. of Geological & Environmental Sciences, Stanford
University, Stanford, CA 94305-2115, USA
(*correspondence: [email protected])
2
Stanford Synchrotron Radiation Lightsource, SLAC National
Accelerator Laboratory, Menlo Park, CA 94025, USA
1
Southern Cross GeoScience, Southern Cross University,
Lismore, NSW, Australia
(*correspondence [email protected])
2
CRC CARE, University of South Australia, Mawson Lakes,
SA 5095, Australia
Ferrihydrite (Fh), a hydrated, nanoparticulate, high surface
area, reactive Fe-oxide, impacts the mobility of inorganic and
organic pollutants through sorption reactions in a variety of
natural environments. Aluminous Fh is common in nature
primarily because of the natural abundance of Al. However,
few studies have dealt with Al-Fh, and thorough structural
analyses of this phase are lacking. The mode of association of
Al with Fh may vary from true chemical substitution, to
surface precipitation, to formation of a mixture of two (or
more) individual nanoscale phases. This may have a
considerable effect on the composition and/or structure of Fh
nanoparticle surfaces, and thus on their surface reactivity and
their interaction with pollutant species.
Here we used a variety of laboratory (TEM, NMR), and
synchrotron-based techniques (X-ray total scattering and PDF
analysis, scanning transmission x-ray microscopy) to
characterize two Al-Fh series synthesized at variable
precipitation rates in the presence of 5 to 40 mol % Al. We
find that roughly 25 mol % Al is incorporated in Fh,
regardless of the synthesis method we used. Phase separation
(formation of Al-hydroxides, e.g., gibbsite) was most
significant at Al concentrations above 30 mol % Al. However,
Al-hydroxide phases were also detected in samples of lower
Al content (as low as 15 mol % Al), particularly in the slowly
precipitated series; this finding may be a result of the kinetics
of co-precipitation. Furthermore, it appears that the amount of
Al incorporated in Fh is not affected by the synthesis method
and is more likely controlled by the accumulated strain caused
by Al in the Fh lattice. Finally, the surface reactivity of
selected Al-Fh samples was investigated by Zn-adsoprtion
experiments, which indicate a slight decrease in overall Zn
adsorption in comparison to pure Fh. Our results provide an
in-depth look at the structure and surface of Al-Fh, as well as
insights about the interaction between Al and Fe during coprecipitation.
Drainage and excavation of coastal lowlands for
agricultural and urban development often results in the
oxidation of underlying Fe-rich sulfidic sediments. Exposure
and subsequent dissolution of these sulfide minerals creates
acidity in the form of sulfuric acid and ferrous Fe [1]. The
coupled processes of oxidation and acidification result in the
release and re-partitioning of Fe and associated trace metals
from stable, reduced mineral phases to more mobile, oxidised
forms. Elevated metal concentrations are commonly
associated with the drainage waters of these landscapes [2]
We followed the partitioning changes to Fe and Cu during
the short-term oxidation and acidification of two acid sulfate
soil materials. The “labile”, “acid-soluble”, “organic”,
“crystalline oxide”, pyritic” and “residual” metal pools were
measured sequentially [3].
Initially Fe and Cu were stored in the “pyritic”, “acidsoluble” and “residual” metal fractions. The “residual”
fraction measured changed little during the 90-day oxidation
experiment, indicating that it was not a major source for Fe
and Cu to more mobile fractions during short-term oxidation
events. The “pyritic” fraction, however, is dominated by
minerals which undergo oxidative dissolution when exposed
to atmospheric oxygen. Major re-partitioning of Fe and Cu
was expected and observed - metals initially associated with
the “pyritic” fraction were re-distributed to more
environmentally available fractions i.e. the “acid-soluble” and
“labile” fractions. The “acid-soluble” fraction was a major
source of metals both initially and as oxidation progressed.
The shift to “labile” and thus leachable metal pools did not
occur until conditions of extreme acidification (i.e. pH <4)
were reached.
As the “labile” fraction poses the most immediate
environmental hazard, managing soil acidity will be the most
effective means for reducing Fe and Cu mobility in acid
sulfate soils.
[1] Sundström and Åström (2006) Bor. Environ. Res. 11, 275281[2] Nordmyr et al. (2008) Est. Coast. Shelf Sci. 76, 141152 [3] Claff et al. (2010) Geoderma 155, 224-230.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Non-invasive geophysical imaging for
characterization of engineered in situ
radionuclide precipitation
Combustion aerosol over marine
stratus: Long range transport,
subsidence and aerosol-cloud
interactions over the South East
Pacific
BOYCE CLARK1*, JEFF GILLOW2, PAUL PRESTON3,
BERNIE ILGNER1 AND SCOTT MORIE4
ARCADIS U.S., Inc., Baton Rouge, LA 70816, USA
(*correspondence: [email protected]);
2
Highlands Ranch, CO 80129, USA
([email protected]);
3
Knoxville, TN 37934 ([email protected],
[email protected])
4
Nuclear Fuel Services, Erwin, Tennessee 37650
([email protected])
1
Stabilization of aqueous-phase uranium can be achieved
through injection of degradable organic carbon to create
anaerobic conditions. Uranium is soluble under aerobic
conditions, exhibiting complex geochemistry and persistence
in these environments. Under anaerobic conditions, uranium
reductively precipitates to the insoluble uraninite mineral
phase. Under these conditions, oxidized iron minerals are
transformed to reduced iron minerals such as iron sulfide.
Under aerobic conditions, the reduced iron minerals provide
stability to the uraninite by acting as a redox buffer and
physical encapsulant. Formation of these reduced iron sulfide
minerals can be engineered through the injection of soluble
iron and sulfate along with degradable organic carbon. At
Nuclear Fuel Services in Erwin, TN, localized areas of the
facility with low concentrations of uranium in groundwater are
being treated with in-situ reductive precipitation of uranium
and engineered precipitation of reduced iron sulfide minerals.
In order to non-invasively characterize the treatment zone,
time-domain induced polarization (IP), a surface geophysical
technique capable of locating iron and sulfide minerals based
on their chargeability was used to guide a drilling program.
Based on the IP imaging, soil cores were obtained. The cores
were analyzed using advanced mineralogical characterization
methods including scanning electron microscopy, energy
dispersive x-ray spectroscopy, microprobe x-ray fluorescence,
and x-ray absorption spectroscopy to evaluate the elemental
association and valence state of uranium, sulfur, and iron. The
results of this comprehensive characterization indicates that
targeted phases are forming in the soil as a result of treatment.
This presentation will discuss the soil characterization,
coupled with non-invasive geophysical characterization and
strategy for the in-situ engineered precipitation of soluble
uranium through creation of reactive mineral phases.
Mineralogical Magazine
679
A. CLARKE1*, S. FREITAG1, J. SNIDER2, J. KAZIL3,4,
G. FEINGOLD4, T. CAMPOS5 AND V. BREKHOVSKIKH1
University of Hawaii, Honolulu, HI, USA
(*correspondence: [email protected])
2
University of Wyoming, Laramie, WY, USA
3
CIRES, University of Colorado, Boulder, CO, USA
4
NOAA, Earth System Res. Lab., Boulder, CO, USA
5
NCAR, Boulder, CO, USA
1
The worlds largest stratus deck over the South East Pacific
(SEP) was a study target for the VOCALS
(http://www.eol.ucar.edu/projects/vocals/)
experiment
in
October 2008. Aerosol-cloud interactions were one major
goal of several ship and aircraft studies including results from
14 flights of the NCAR C-130 aircraft reported here. Each
flight covered about a 1000 km range with multiple profiles
and legs below, in and above the Sc deck.
Strong aerosol sources along the coast of Chile were
expected and found to influence cloud condensation nuclei
(CCN) in coastal clouds. However; “rivers” of elevated CO,
black carbon (BC) associated with combustion aerosol
effective as CCN at <0.3%S were also common in subsiding
FT air overlying the extensive Sc deck for over 1000km
offshore. This subsidence, linked to the Hadley circulation,
brought in aerosol from sources over the western Pacific as
well as South America. Observed entrainment of this aerosol
was linked to cloud related turbulence. When present, this
combustion aerosol increased available CCN and decreased
effective radius compared to clouds in “clean” MBL air
advected from the South Pacific. We hypothesize that this
entrainment can help buffer MBL clouds over the SEP against
depletion of CCN by drizzle. This may delay transition of
closed cell to open cell convection, potentially leading to
increased lifetimes of Sc clouds that entrain such aerosol.
www.minersoc.org
680
Goldschmidt Conference Abstracts
The structure and topology of
cytochromes involved in outer
membrane electron transport
T.A. CLARKE1*, M.J. EDWARDS1, A.M. HEMMINGS1,
A. HALL1, G. WHITE1, A. GATES1, J.N. BUTT1, L. SHI2,
J. FREDRICKSON2, J. ZACHARA2 AND D.J. RICHARDSON1
Centre for Molecular and Structural Biochemistry, School of
Biological Sciences, Univ. of East Anglia, Norwich, UK
(*correspondence : [email protected])
2
Pacific Northwest National Laboratory, Richland, WA, USA
1
Characterisation of Outer Membrane Cytochromes.
Extracellular mineral respiration is dependent on the
correct expressionof an outer membrane porin-cytochrome
complex, where a large transmembrane porin mediates direct
electron transfer between a small decaheme periplasmic
cytochrome and an extracellular decaheme cytochromeon the
cell surface. [1] Over 30 % of the Shewanella oneidensis
surface is covered with these outer membrane cytochromes
and it has been shown that there are multiple members of the
outer membrane cytochrome family are capable of interacting
with a broad range of mineral oxides [2,3].
Figure 1: Structure of MtrF, a decaheme outer membrane
cytochrome involved in mediating electron transport between
S. oneidensis and extracellular mineral.
We have resolved the crystal struture of one of these outer
membrane cytochrome, shown in figure 1, and this has
revealed that these proteins comprise a c-type cytochrome
core flanked by two %-barrel domains [4]. This structure
provides a base for understanding how these systems interact
with both the outer membrane and the extracellular
enviroment.
[1] Hartshorne et al. (2009) P.N.A.S.106, 22169-74 [2] Lower
et al. (2007) Appl. Env. Microbiol. 75, 2931-2935 [3] Shi et al.
(2009) Env. Microbiol. Reports 1, 220-7. [4] Clarke et al.
(2011) P.N.A.S. Accepted for publication.
Mineralogical Magazine
Plate- versus plume-driven processes
– South Atlantic DUPAL revisited
C. CLASS1* AND A. P. LE ROEX2
Lamont-Doerty Earth Observatory, Palisades, NY10964,
USA (*correspondence: [email protected])
2
University of Cape Town, Rondebosch, 7701, South Africa
1
The DUPAL anomaly in the South Atlantic is present in
intra-plate volcanism associated with the Tristan-Gough,
Discovery and Shona plumes, and along adjacent sections of
the southern Mid-Atlantic Ridge. Its origin has been variably
attributed to either plate-driven processes introducing
continental material into the shallow mantle, or plume-driven
processes sampling sources in the lower mantle, which cannot
be distinguished based on geochemical arguments alone. Here
we present an integration of geochemical arguments and
dynamic considerations and test the following hypotheses:
(1) South American origin – Previous geochemical
evidence suggests that the DUPAL originates from the South
American sub-continental lithospheric mantle (SCLM),
possibly thermally eroded by the Tristan plume head.
However, our mass balance calculation shows that an
unrealistic volume of SCLM would be needed for the
contamination of thousands of cubic km of upper mantle in a
direction unsupported by any obvious mantle flow regime.
(2) South African origin - A mantle flow field induced by
the African Superplume has been inferred previously from
seismic anisostropy, suggesting mantle flow from beneath
Africa and possible contamination of the S Atlantic upper
mantle with African plate material. However: (i) off-craton
SCLM and lower crustal samples provide no evidence in
support of thermally eroded or tectonically detached African
plate material being the origin of the S Atlantic DUPAL
anomaly [1]. (ii) Erosion of the base of the Kaapvaal craton by
the Superplume-related mantle flow is not supported by
available constraints on the composition of the Kaapvaal
SCLM [1]. In addition, volcanism from upper mantle melting
anomalies at Vema and 7 degree Seamount do not support an
overall contamination of the S Atlantic shallow mantle [1].
(3) Deep origin – A deep, plume-related origin of the S
Atlantic DUPAL is supported by the spatial extent of the
anomaly in S Atlantic MORB adjacent to DUPAL plumes.
Mixing systematics are consistent with the different plumes
showing plume-ridge interaction as a function of distance to
the ridge. Extreme isotopic heterogeneity of the S Atlantic
DUPAL source is indicated from plume trail samples of the
DUPAL plumes. Similarities and differences to Indian and
Pacific Ocean DUPAL anomalies are explored.
[1] Class & le Roex (2011) EPSL 305, 92-102.
www.minersoc.org
Goldschmidt Conference Abstracts
Ecological impact of submarine
groundwater discharge in a
Mediterranean lagoon: Correlations
between radon, radium and nitrate in
the Mar Menor, Murcia, Spain
CHRISTELLE CLAUDE1, PAUL BAUDRON*23,
ADRIANO MAYER1, JAVIER GILABERT 4,
DAVID MARTINEZ VICENTE2 , OLIVIER RADAKOVITCH1,
CHRISTIAN LEDUC3, JOSE LUIS GARCIA AROSTEGUI5,
2
AND FRANCICO CABEZAS CALVO-RUBIO
CEREGE, Europôle de l’Arbois, 13545 Aix-en-Provence,
France, ([email protected])
2
F-IEA, Complejo de Espinardo, C\ Nacional 301, 30100
Murcia, Spain, ([email protected])
3
G-EAU, BP 5095, 34196 Montpellier cedex 5, France,
([email protected])
4
Department of Chemical & Environmental Engineering,
Technical University of Cartagena (UPCT), Alfonso XIII,
52, E30203, Cartagena, Spain, ([email protected])
5
IGME, Avenida Miguel de Cervantes, 45, 30009 Murcia,
Spain, ([email protected])
1
Since 15 years numerous works have shown the influence
of submarine groundwater discharge (SGD) on the water
budget of lagoons, bays or open coastal areas [1]. In particular
the high concentrations in nutrients of discharging
groundwater may result in very productive ecosystems [2]. A
radon-radium study was coupled with nutrients in semi-arid
South-Eastern Spain. Mar Menor lagoon (135 km2) is
bordered by a Quaternary sedimentary aquifer extending over
1200 km2. 222Rn and 224Ra activities in groundwaters along the
coast range between 2200 to 17500 and 16 to 120 Bq/m3
respectively. In the lagoon, 222Rn and 224Ra activities varied
from 10 to 100 and 4 to 8 Bq/m3 respectively. The increase of
both nuclides is localized and synchronous with a peak in
NO3- and chlorophyll, revealing groundwater input. In the
same area, changes observed in coastal vegetation could be
related. Further measurements will refine the SGD flux to Mar
Menor and its ecological impact.
[1] Moore W. S. (1996), Nature 380, 612-614. [2] Laroche, J.,
Nuzzi, R., Waters, R., Wyman, K., Falkowski, P.G., and
Wallace, D.W.R. (1997), Global Change Biology 3, 397-410.
Mineralogical Magazine
681
Uranium-series mobility during
spheroidal weathering of 300 kyrs old
basalt (La Réunion Island)
CHRISTELLE CLAUDE1, JEAN-DOMINIQUE MEUNIER*1,
DAOUDA TRAORE2, FRANÇOIS CHABAUX3,
BRUNO HAMELIN1 AND FABRICE COLIN2
CEREGE, Europôle de l’Arbois, 13545 Aix-en-Provence,
France, ([email protected])
2
IRD, Anse Vata, BP A5, 98848 Nouméa Cedex, New
Calédonia, ([email protected])
3
Laboratoire d'Hydrologie et de Géochimie de Strasbourg
EOST, 1 rue Blessig , 67084 Strasbourg cedex,
([email protected])
1
Spheroidal weathering (also named corestone-shell
systems hereafter called CSS) is a common form of chemical
weathering affecting many types of rocks [1]. The spheroidal
structures are good models for studying weathering budget
because the volume of shell rocks during weathering is
conservative [2]. The CSS constitute therefore an open system
for mobile elements such the major cations and silica that are
leached out of the units. Conversely, they also can be seen as a
closed system relative to poorly mobile elements such as Ti,
Al or Fe which are only displaced from the core to the outer
shell. During chemical weathering processes, natural radionuclides from the uranium series are either mobile or
refractory and this differentiated behavior disturbs the status
of radioactive secular equilibrium characterizing geological
234
U-238U-230Th
formations.
Consequent
radioactive
disequilibria can be used as a tool to estimate rate of soil
formation on a time scale of circa 1 Ma. Here we combine
mineralogical observations, geochemistry of major and trace
elements to Sr isotopes and U-series as an attempt to
constraint the rate of spheroidal weathering of a basaltic flow
dated at 292 ±10 ka from la Reunion Island. U-transport
model shows a remobilization process occurring on a timescale of ca 250 ka. 87Sr/86Sr variations are small (0.7042 0.7050). Highly mobile Sr is leached out in 1500 yrs only. Sr
fluxes are 1 order of magnitude higher than steady state
conditions [3] suggesting that weathering rates could be higher
during the first stages of alteration.
[1] Ollier, C.D., (1971), Earth Sci. Rev. 7, 127-141. [2] Patino,
L.C., Velbel, M.A., Price, J.R., Wade, J.A., (2003). Chem.
Geol. 202, 343-364. [3] Rad, S.D., Allègre, C.J., Louvat, P.,
(2007), Earth Planet Sci. Lett. 262, 109-124.
www.minersoc.org
682
Goldschmidt Conference Abstracts
Evolving isotopic fluxes to Asian
marginal seas controlled by Monsoon
strength since the Last Glacial
Maximum
PETER D. CLIFT, DENGKE HU AND DAVID LIMMER
School of Geosciences, University of Aberdeen, Aberdeen,
AB24 3UE, UK
The intensity of the Asian monsoon is expected to have a
major impact on the strength of erosion and chemical
weathering in continental river basins. Because these
processes are linked to solar insolation there should be major
variations in the chemical flux to the ocean on millennial
timescales. To test this hypothesis we have examined the
erosional response of rivers in different parts of Asia to
monsoonal changes since 14 ka. ODP Site 1144 in the South
China Sea shows little provenance variation, but a major
changes in Sr isotope composition, clay mineralogy, clastic
mass accumulation rates and Ti/Ca values. We interpret this to
reflect erosion of Pleistocene fluvial terraces in Taiwan and
from the exposed Taiwan Strait during early Holocene
monsoon intensification. The isotope and chemical proxy
pulse lasts from 11 to 8 ka, considerably shorter than the
period of strong summer monsoon derived from speleothem
records. Assuming these latter to be robust rainfall proxies we
suggest that the fall in weathering intensity after 10 ka reflects
decline in the erosion of the terraces onshore as the valleys are
emptied and the Taiwan Strait was drowned by rising sealevel.
In the Pearl River estuary itself we see a clear but different
signal. Here 87Sr/86Sr values rise after 9 ka and only begin to
fall again after 6 ka, reaching minimum values at 3.5 to 1.0 ka.
If Sr isotopes are controlled by weathering then the response
appears to lag monsoon intensity by ~2 k.y. A major increase
in 87Sr/86Sr after 1.0 ka and the large mis-match between
modern river sediments and the Holocene delta suggests major
changes in erosion patterns, probably caused by the expansion
of farming. Further west in the Indus delta Nd and Sr isotopes
change quickly during from 14 to 9 ka as the monsoon
intensifies, likely driven by changing patterns of erosion as the
location of heaviest rains migrates. In the offshore shallow
delta rising 87Sr/86Sr values during the early Holocene also
suggest stronger chemical weathering. The effect is strongest
in the early Holocene, but does not reduce after the weakening
of the monsoon after ~5 ka. We suggest that reworking of
older more weathered material from the flood plain at that
time buffers the flux to the ocean. Although a wetter monsoon
might be expected to drive more chemical weathering we find
that on millennial timescales reworking of material formed
during drier glacial times is often the source of the most
weathered materials.
Mineralogical Magazine
H isotopes in lavas from Loihi and
Pitcairn: Primitive or recycled
water?
M. CLOG*, C. AUBAUD AND P. CARTIGNY
Laboratoire de Géochimie des Isotopes Stables, IPGP,
UMR7154, 1 rue Jussieu, 75005 Paris, France
(*corresponding author, [email protected])
Hotspots sample mantle domains distinct from mid-ocean
ridge systems. The source of hotspot lavas has been shown to
contain recycled, subducted materials but also primitive
material as seen from noble gases isotopic compositions.
Water contents are higher in OIBs than in MORB but due to
divergent H2O/Ce and (D measured on different hotspots,
there is presently no consensus on either the origin of water in
hotspot lavas or even if there still is juvenile water in their
sources. Lavas from Loihi seamount and Pitcairn both contain
EM-1-type material and have primitive neon isotopic
compositions, pointing at a mixing between recycled and
primitive components in the mantle, and making the
comparison of H systematics between the two hotspots key to
shed light on the potential existence of primitive water. 7
samples from Loihi and 17 from the active zone of the Pitcairn
hotspot were analysed in this study. Water concentrations
measured by manometry range from 0.4 to 0.9% for Loihi and
0.5 to 1.2% for Pitcairn, while (D range respectively from -72
to -65‰ and -53 to -36‰. All but one sample from Loihi are
unaffected by degassing, and the H2O content variations are
mainly due to variations of partial melting and crystal
fractionnation. The (D of the 6 other samples are very
homogenenous (-67.9±1.5‰). For the Pitcairn samples, initial
water concentrations and isotopic compositions are calculated
using the concentrations and (D of water in the vesicles,
assuming closed-system degassing for water.
In Pitcairn samples, the results are compatible with a twocomponents mixing, one D- ((D>-40‰) and water-rich
(H2O/Ce>150), and the other D- ((D<-45‰) and water-poor
(H2O/Ce<125). The water-rich samples are also those richest
in incompatible trace elements. Previous studies [1,2] have
shown that in samples from Pitcairn, the ones most affected by
the EM-1 component have primitive neon isotopic
composition and are also richer in incompatible elements. The
contrasted (D between the two hot-spots suggests that the
component bearing primitive Ne is water-poor, and, thus, that
water in Pitcairn comes from recycling processes.
[1] Honda and Woodhead (2005), EPSL 236, 597-612 [3]
Eisele et al (2002), EPSL 196, 197-212.
www.minersoc.org
Goldschmidt Conference Abstracts
Zn mobility during oceanic crust
alteration inferred by its isotopic
composition
Calcium isotope fractionation during
plant growth under limiting and
non-limiting nutrient supply
C. CLOQUET1*, J. CARIGNAN1,2 AND
C. FRANCE-LANORD1
CRPG/CNRS, BP 20, 54501, Vandoeuvre-lès-Nancy, France
(*correspondance: [email protected])
2
Takuvik, CNRS-ULaval, Québec, G1V 0A6, Canada
F. COBERT1, A.-D. SCHMITT2, P. BOURGEADE2,
F. LABOLLE3, P.-M. BADOT2, F. CHABAUX1 AND
P. STILLE1
1
In the last 10 years, with the multiplication of MC-ICPMS, our knowledge of the transition metal isotope
geochemistry has been expanded. Among the studied
elements, Zn became a useful tracer in biological systems and
to trace anthropogenic activities [1,2]. However, Zn
geochemical behaviour still suffers from lack of information
and remains not well characterised.
In this work, we studied volcaniclastic sediment and
basalts from ODP Leg 129, Sites 800 & 802A, located in the
northern Pigafetta Basin near the HIMU Seamount and in the
center of the East Mariana Basin. The two sites were drilled
for about 500 m through sediment sequence largely
constituted of volcaniclastic sediments. Calcium and Sr
contents and Sr isotopes already demonstrated the role of
diagenetic reactions in these cores. The aim of the study was
to investigate the mobility of Zn during various reactions
occurring in these cores like alteration, diffusion and
diagenetic processes in real samples.
After Zn isolation from the matrix, the isotopic
composition was measured by MC-ICP-MS. All the results are
expressed relative to IRMM 3702 which presents a #66Zn of
+0.3‰ compared to JMClyon. The #66Zn total range is from 0.1
to 0.6‰ for the two cores, the highest value being found at the
top of the core. Both cores present a similar behaviour with a
mean value around 0.3‰ reflecting their relative homogeneity
in the volcaniclastic sediments. The value obtained for the
basalt is also around 0.3‰ which is higher than values
reported so far for fresh basalts (0‰). Zn isotopes do not fully
follow Sr isotopes behaviour. However, a trend of the Zn
isotopic composition to the light value from the top to the
bottom of the core is observed. Such a variation can be
interpreted in term of interaction between the sea water and
the sediments from one part and between hydrothermal fluids
and sediments from an other part.
[1] Weiss et al. (2005) New Phyto. 165, 703-710. [2] Cloquet
et al. (2006) Environ. Sci. Technol. 40, 6594-6600.
Mineralogical Magazine
683
Laboratoire d'Hydrologie et de Géochimie de Strasbourg;
Université de Strasbourg/EOST, CNRS; 67000
Strasbourg, France.
2
Université de Franche-Comté et CNRS-UMR 6249, Chronoenvironnement, 25030 Besançon Cedex, France.
3
Université de Strasbourg, Institut de Zoologie et de Biologie
générale, 67000 Strasbourg, France.
1
Hydroponic experiments have been performed to identify
the co-occurring geochemical and biological processes
affecting Ca isotopic compositions within plants. Four
experiments have been conducted combining two Ca
concentrations (5 and 60 ppm) and two pHs (4 and 6). Another
experiment was performed with limiting Ca nutrient supply at
5 ppm Ca and pH=6. All the experiments have been achieved
on bean plants in order to have access to a complete growth
cycle in a short duration. Several organs (root, stem, leaf,
reproductive) were sampled at two different growth stages (10
days and 6 weeks of culture).
Our results show, in agreement with previously published
field studies [1, 2, 3,4], that all the bean organs are enriched in
the light 40Ca isotope compared to the nutritive solution.
Moreover, Ca concentrations and pH influence Ca isotopic
composition within plant organs. We identified three
fractionation levels. The first one occurs during the uptake of
the nutrient elements by the lateral roots. The second one takes
place during the long distance transport of Ca, from roots to
shoots. The third one takes place during formation of
reproductive organs. The experiment with limited Ca supply
shows a 44Ca enrichment in solution through time; the plants
seem to establish an isotopic equilibrium with the nutrient
solution.
The data confirm the potential of the Ca isotopic system
for tracing biological fractionations in ecosystems.
[1] Wiegand et al., (2005). Geophys. Res. Lett., 32, L11404.
[2] Page et al., (2008). Biogeochemistry, 88, 1-13. [3] CenkiTok et al,. (2009). GCA, 73, 2215-2228. [4] Holmden and
Bélanger (2010). GCA, 74, 995-1015.
www.minersoc.org
684
Goldschmidt Conference Abstracts
Gold scavenging by liquid bismuth
melts
A. B. COCKERTON* AND A. G. TOMKINS
School of Geosciences, Monash University, PO Box 28E,
Victoria 3800, Australia
(*correspondence: [email protected])
Bismuth is associated with gold in several different types
of ore deposits. It has a melting temperature of only 271°C
and therefore, when bismuth becomes saturated in a
hydrothermal fluid at temperatures above this, it will
precipitate from the fluid, not as a solid, but as a liquid. This
liquid bismuth can subsequently continue to interact with and
be transported by the hydrothermal fluid. Numeric modelling
has shown that gold concentrations become several orders of
magnitude higher in a bismuth melt versus the corresponding
Bi-absent hydrothermal fluid, supporting the theory that a
bismuth melt can scavenge and concentrate gold and other
metallic ions from the hydrothermal fluid [1]. This theory is
known as the Liquid Bismuth Collector Model (LBCM) [2].
We have investigated the bismuth-rich Stormont gold
prospect in north-western Tasmania, to test the LBCM.
Conditions at Stormont have been found to be favourable for
bismuth to have precipitated as liquid with mineralisation
temperatures between 400-500°C. In situ evidence for goldscavenging by liquid bismuth is observed in the close textural
relationship between native gold and bismuth. Zoned
andradite crystals suggest hydrothermal fluid composition
fluctuations, which may have contributed to zone refinement
within the prospect. Liquid bismuth can sequester gold from
undersaturated fluids [1]. Therefore, a zone refining process
can potentially operate in a system where repeatedly
infiltrating undersaturated fluids, controlled by favourable
structures, can dissolve gold not attached to bismuth and then
re-precipitate it where bismuth is concentrated. This leads to
enhanced correlation between the two elements.
[1] Tooth et al. (2008), Geology 36, 815-818. [2] Douglas et
al. (2000), 15th Australian Geological Convention, 135.
Revealing the hidden signature of
biomacromolecules in ancient organic
fossils
G.D. CODY1, R.M. HAZEN1, S.N. GUPTA2 AND
A.L.D. KILKOYNE3
Geophysical Laboratory, Carnegie Institution of Washington,
Washington DC 20015 USA ([email protected])
2
Indian Institute of Science Education and Research, India
3
Advanced Light Source, Lawrence Berkeley Laboratory,
Berkely, CA, USA
1
The organic fossil record of eukaryotic organisms reaches
back to the dawn of the Paleozoic. In the case of the
arthropod fossil record, the preserved organic residue is
derived from arthropod’s exterior cuticle, the rigid
exoskeleton characteristic of all members of the Arthropod
phylum. In modern arthorpods, the exocuticle is composed of
a nanocomposite of chitin and structural protein with very
exterior region also containing fatty acids. The conventional
geochemical view holds that the biopolymer chitin and
structural protein is not preserved in ancient fossils as they are
readily degradable through microbial chitinolysis and
proteolysis and otherwise susceptible to destruction during
diagenesis. Recently, however, we showed that a clear
molecular signature of relict chitin-protein complex is
preserved in a Middle Pennsylvanian (310 Ma) scorpion
cuticle and a Silurian (417 Ma) eurypterid cuticle via analysis
with carbon, nitrogen and oxygen X-ray Absorption Near
Edge Structure (C-, N-, and O-XANES) spectro-microscopy
[1]. The application of high-resolution X-ray microscopy
employing functional group derived absorption contrast
reveals the complex laminar variation in major biomolecule
concentration across modern scorpion cuticle; XANES spectra
highlight the presence of the characteristic functional groups
of the chitin-protein complex. Modification of this complex is
evident via changes in organic functional groups. Both fossil
cuticles contain considerable aliphatic carbon relative to
modern cuticle. In both cases, however, the concentration of
vestige chitin-protein complex is high, 59 and 53 % in the
fossil scorpion and eurypterid, respectively. We have recently
used the Scanning Transmission X-ray Microscope (STXM) at
beam line 5.3.2 at the Advanced Light Source to analyze the
preserved organic cuticle of a Cambrian (507 Ma) trilobite
from the Wheeler Shale. The thin section was prepared using
a focused ion-beam mill. We detect very high N/C and O/C
consistent with preservation of abundant, albeit altered,
remnants of chitin/protein complex.
[1] Cody et al. (2011) Geology 39, 255-258.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Large weakening in monsoonal
rainfalls over western India during
the Younger Dryas
Early Ordovician volcanism in
Eucísia and Mateus areas, Central
Iberian Zone, northern Portugal
ANTOINE COGEZ1*, LAURE MEYNADIER1,
CLAUDE ALLÈGRE1 AND FRANCK BASSINOT2
Equipe de Géochimie et Cosmochimie, Institut de Physique
du Globe de Paris, Sorbonne Paris Cité, Univ Paris
Diderot, UMR 7154 CNRS, F-75005 Paris, France
(*correspondence: [email protected])
2
Laboratoire des Sciences du Climat et de l’Environnement,
CEA, CNRS, Gif sur Yvette, France
685
C.J.M. COKE1, R.J.S. TEIXEIRA1, M.E.P. GOMES1,
F. CORFU2 AND A. RUBIO ORDÓÑEZ3
Department of Geology, UTAD, Apartado 1013, 5001-801
Vila Real, Portugal ([email protected], [email protected],
[email protected])
2
Dep. of Geosciences, Univ. of Oslo, PO Box 1047 Blindern,
N-0316 Oslo, Norway ([email protected])
3
Dep. of Geology, Univ. of Oviedo, C/ Jesús Arias de Velasco,
33005 Oviedo, Spain ([email protected])
1
1
We studied the monsoonal rainfalls evolution since 30
kyrs over western India, using neodymium isotopes (#Nd) in
sediment cores. Since neodymium isotopes are not
fractionated by physico-chemical processes, they are an
excellent tracer of mixing in seawater between different
continental sources weathered by rainfalls. Using this
technique Gourlan et al. (2010) already found that Ganges and
Brahmaputra discharge was 3 times stronger during
interglacial than during glacial times. To test such a result for
the Western Gaths in India where the precipitations are among
the strongest in this area, we measured #Nd since 30 kyrs in 5
oceanic cores, one in the middle of the Arabian Sea, two along
the Western Indian Coast and two south of India, on the
Maldives Plateau. The carbonate phase and Mn coatings
around foraminiferae were leached using acetic acid; we also
measured #Nd in the detrital fraction of the sediment because
it carries the signature of the sources. Dating was performed
using (18O in planktonic foraminiferae from the same cores
and three or four radiocarbon dates per cores.
Both signals from the cores located along the Western
Gaths display a large positive peak synchronous with the
Younger Dryas (YD) event, 12 kyrs ago. Using a first order
mixing model we estimate that local precipitations could have
been up to 5 times weaker during this period. Moreover the
recovery to Holocene rain level could have been much more
longer than the onset. To our knowledge this is the first time
that #Nd records display a dependency of monsoon rain on
YD event. This clearly show that monsoon regime was
controlled by Northern Hemisphere climate regime. Large
amplitude differences are seen when comparing #Nd to (18O
in planktonic foraminiferae.
The three other cores display a pattern characteristic of the
deglaciation (decreasing #Nd since the Last Glacial
Maximum) without the trace of YD and rather correlated with
the (18O records. We surmise that those patterns are imprinted
by Himalaya where ice covering has a large influence on the
precipitations and sediments discharge.
The Eucísia (Alfândega da Fé) and Mateus (Vila Real)
areas are located in the Central Iberian Zone, a segment of the
northern Gondwana margin which underwent a long Variscan
geodynamic evolution. Lithostratigraphically both areas are
characterized by a predominance of Precambrian to Cambrian
metasedimentary rocks and by the transgressive nature of the
Ordovician formations. Continental rifting on the platform of
northern Gondwana began around the Middle Cambrian, and
opening of the Rheic ocean took place near the OrdovicianCambrian boundary. In the Eucísia and Mateus areas there is
evidence of extensional volcanism related to these events,
contemporaneous with a transient inversion, known as the
Sardic phase. At Eucísia the Ordovician Armorican Quartzite
Formation hosts a < 40 cm thick ash-fall tuff bed, which is
mainly composed by muscovite and small amounts of quartz.
At Mateus, a subvolcanic porphyritic rock occurs in a 3 m
thick vein cutting Precambrian-Cambrian schists. The
phenocrysts consist of euhedral/ovoidal plagioclase and
microcline and rounded bluish quartz. The groundmass is
dark, fine grained and contains quartz, feldspars, muscovite,
rare biotite and graphite (identified by XRD). The
mineralogical and textural features of this vein resemble those
of the augen gneisses from the Ollo de Sapo Formation in
Sanabria (Spain), except for a lower degree of
deformation/recrystallization. The tuff and the porphyry are
both alkali-calcic, peraluminous (ASI ' 1.75 – 2.91) and
classified as rhyolites in the R1-R2 diagram. They show
moderate REE contents (I ' 78.3 – 182.6), (La/Lu)N values
between 11.78 and 12.06, weak negative Eu anomalies
(Eu/Eu* ' 0.45 – 0.52) and REE patterns typical of
peraluminous granites. Both rocks have a high content of
zircon xenocrysts, but also some magmatic zircon prisms
which were dated by U-Pb (ID-TIMS) yielding concordia ages
that indicate crystallization in the Early Ordovician: the ashfall tuff from Eucísia at 482.1 ± 1.5 Ma and the rhyolite
porphyry from Mateus at 478.0 ± 1.7 Ma.
Mineralogical Magazine
www.minersoc.org
686
Goldschmidt Conference Abstracts
Bioengineering nano-magnetite for
contaminant clean-up
PGE contents and spinel
compositions of different podiform
chromitites in the Eastern Anatolia
complex, Turkey
V.S. COKER1*, D. CREAN2,1, R.S. CUTTING1,
N.D. TELLING3, J.M. BYRNE1, R.A.D. PATTRICK1,
G. VAN DER LAAN4,1, D.J. VAUGHAN1 AND J.R. LLOYD1
SEAES, University of Manchester, M13 9PL, UK
(*correspondence: [email protected])
2
Department of Materials Science & Engineering, University
of Sheffield, S1 3JD, UK
3
Institute for Science & Technology in Medicine, Keele
University, Stoke-on-Trent ST4 7QB, UK
4
Diamond Light Source, Didcot, Oxfordshire OX11 0DE, UK
1
The engineering of novel materials is a key development
in the challenge of remediating toxic metals and radionuclides
in the subsurface. Our work focuses on utilising nano-scale
magnetite, synthesised through the bioreduction of ferrihydrite
by Geobacter sulfurreducens at ambient temperatures. In
order to increase the activity and longevity of this substrate in
key reactions, including chromium(VI) and toxic organics
reduction, the surface of the nano-magnetite is functionalised
by a precious metal catalyst, nano-palladium, in a simple, onestep process, aided by the organic residue on the iron mineral
surface derived from the bacterial culture [1].
Pd-functionalised nanomagnetite has been tested in the
remediation of Cr(IV) in batch and continous-flow column
experiments and in hollow-fibre membrane units. Conditions
in the column studies were varied to take into account key
environmental parameters including oxic, anoxic, and a nitrate
co-contamination. An electron donor, sodium formate, was
supplied in the influent leading to a substantial increase in the
removal capacity of the Pd-magnetite. In addition, the
columns containing both Pd-biomagnetite and formate were
found to maintain an 80 % removal beyond 300 hours,
whereas without formate complete breakthrough occurred at
60 hours. We hypothesise that oxidation of formate in these
experiments is coupled to recharge of the nanocatalyst surface
by the Pd, maintaining the reductive power of the system.
Cr(III) formed was associated strongly with the
biomagnetite, and XMCD studies suggest that the Cr(III)
replaces Fe in the magnetite lattice, effectively ‘locking-up’
the Cr, as seen previously [2]. This novel system could
provide effective and sustained immobilisation of
contaminants, far outreaching the reductive capacity of nonfunctionalised magnetite.
A.R. ÇOLAKOGLU1*, K. GÜNAY1 AND H.M. PRICHARD2
Yüzüncü Yıl University, Department of Geological
Engineering, Zeve Campus, TR-65080 Van, Turkey
(*correspondence:[email protected],
[email protected])
2
School of Earth and Ocean Sciences, Cardiff University,
Main College, Cardiff, CF10 3AT, United Kingdom
([email protected])
1
This study presents mineralogy, PGE contents and spinel
compositions of four different podiform chromitite localities
in the east of Turkey. The ophiolitic rocks are observed as
relatively large tectonic units in the Eastern Anatolian
Accretionary Complex [1]. Chromite texture are observed as
massive, nodular and dissemine-banded type. The highest
value (390 ppb) of &PGE are obtained from milonitic shear
zone chromitites with an average ~290 ppb. Os, Ir and Ru
show relatively enrichment, compare to Pt, Pd and Rh
elements. This enrichment are consistent with other chromitite
deposits in Turkey. Chromite grains contain inclusion of mafic
silicates (olivine, amphibole and clinopyroxene), sulphides
(etc. millerite, heazlewoodite, awaruite, chalcopyrite,
godlevskite, orcelite) and euhedral Laurites. The chromite
compositions of different localities ore exhibit characteristic of
different tectonic setting. The high Cr# and low TiO2 content
of spinel from the eastern Anatolia chromitites possibly has
genetic linkage with a boninite melt generated by high degrees
of partial melting and the others are formed in island arc
setting towards to back arc basin [2, 3].
[1] Sengör et al. (2008) Earth Science Rev. 90, 1-48. [2]
Kamanetsky et al. (2001) Journal of Petrology 42, 655-671.
[3] Zhou et al. (1998) Geochimica et Cosmochimica Acta, 62,
677–688.
[1] Coker et al. (2010) ACS Nano 4, 2577-2584. [2] Cutting et
al. (2010) Environ. Sci. Technol. 44, 2577-2584.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Aerosol spatial scales in observations
and models: Implications for the
aerosol direct effect
PETER R. COLARCO*
Atmospheric Chemistry and Dynamics Branch, NASA GSFC,
Greenbelt, MD 20771, USA
(*correspondence: [email protected]a.gov)
Consideration of variability in aerosol spatial and temporal
distributions are prime concerns in developing sampling
strategies for future satellite missions. Previous studies
suggest homogeneity in tropospheric aerosol spatial
distributions at scales of about 200 km. These studies,
however, did not have access to the extensive global data sets
of aerosols from the past decade of EOS observations, and so
their conclusions on aerosol spatial scales must be viewed as
tentative. In the first part of this study we evaluate what the
global distribution of aerosol optical depth looks for different
spatial sampling strategies. We sample MODIS observations
at their native swath width, along a satellite-subpoint track like
what the APS would have observed, and at an intermediate
swath width similar to what MISR observes. We investigate
the convergence of the aerosol optical depth statistics for all
cases. In the second part of this study we employ these
sampling strategies on the results of the NASA GEOS-5
global aerosol model to investigate the implications for
computed aerosol direct radiative forcing.
Mineralogical Magazine
687
Missed connection: Ignimbrite
seeking plutonic relationship
DREW S. COLEMAN*, RYAN D. MILLS AND
MICHAEL J. TAPPA
Department of Geological Sciences, University of North
Carolina, Chapel Hill, NC 27599-3315
(*correspondence [email protected])
New U-Pb zircon geochronologic data for rocks from the
Southern Rocky Mountain volcanic field demonstrate a
distinct disconnect between the timing of ignimbrite eruption
and plutonism. In both the Questa and Aetna calderas, only
discontinous dikes yield the same ages as ignimbrites. The
dominant volume of exposed plutonic rocks was assembled
either before or after the ignimbrite events.
Geochronology for rocks in the Questa and Aetna calderas
demonstrate that the largest exposed plutons (the Rio Hondo
and Mt. Princeton, respectively) were assembled
incrementally. Data for the Rio Hondo pluton indicate a
magma accumulation rate of 0.0003 km3yr-1 for the exposed
portion of the pluton. Data for the Mt. Princeton pluton
indicate an accumulation rate of 0.0009 km3yr-1. Both rates are
comparable to rates published for other plutons, and orders of
magnitude too slow to accumulate large eruptible magma
volumes. Extrapolation of the accumulation rate for the Rio
Hondo pluton over the 8.5 m.y. history of the volcanic field
yields an estimated volume of plutonic rocks comparable to
the volume under the field indicated by geophysical studies.
We propose that the bulk of the plutonic rocks beneath the
volcanic center accumulated during periods of low volcanic
effusivity (the waxing and waning stages of caldera
formation), and that most of the magma generated during
caldera formation erupted. Furthermore, because the oldest
portion of the Rio Hondo pluton is the granitic cap exposed
beneath a gently dipping roof contact, the roof granite cannot
be a silicic liquid fractionated from the deeper (younger)
portions of the pluton. Instead, the data suggest that the
variation in composition of the pluton is inherited from the
lower crustal source. We suggest that if magma flux is high
enough, zoned ignimbrites can be formed by evolution of the
melt compositions being generated at the source. Thus
eliminating the “need” for large shallow magma chambers and
plutons in support of ignimbrite evolution.
If the intrusive equivalents to the ignimbrites are limited to
dikes, and the plutonic rocks crystallized over the history of
the fields, then the plutonic record of the ignimbrite stage of
caldera formation is sparse. This predicts that the plutonic
record will be dominated by waxing and waning stage
magmatism, and the volcanic record will be dominated by
ignimbrite stage magmatism.
www.minersoc.org
688
Goldschmidt Conference Abstracts
Investigating the effects of hydrologic
fluctuations on organic sulfur
speciation in boreal peatlands
J.K. COLEMAN WASIK1,2*, B.M. TONER3,
D.R. ENGSTROM2, P.E. DREVNICK4 AND M.A MARCUS5
Water Resources Science Graduate Program, University of
Minnesota, St. Paul, MN 55108, USA
(*correspondence: [email protected])
2
St. Croix Watershed Research Station, Marine on St. Croix,
MN 55047, USA
3
Department of Soil, Water, and Climate, University of
Minnesota , St. Paul, MN 55108, USA
4
Centre Eau Terre Environment, Québec (Québec) G1K 9A9,
Canada
5
Advanced Light Source, Lawrence Berkeley National
Laboratory, Berkeley, CA 94720, USA
1
Sulfur has a complex biogeochemical cycle in peatlands
due to its chemical reactivity, wide range of oxidation states,
and importance to bacterial metabolism [1]. In sulfur-limited
systems sulfate plays a synergistic role in the production of
monomethylmercury (MeHg), the bioaccumulative form of
mercury [2]. Therefore an understanding of how sulfate is
incorporated into and released from peat soils may improve
prediction of MeHg production within, and export from,
peatlands. Climatic variability can cause large changes in
oxidation- reduction potentials within peatlands by influencing
the position of the water table. Wetlands are often considered
to be sinks in the landscape for sulfate because sulfate inputs
to saturated systems are readily consumed by sulfate-reducing
bacteria. However, following droughts wetlands have been
found to be significant sources of sulfate to downstream
aquatic ecosystems [3].
This research compared sulfur speciation in peat from a
boreal peatland during and after an historic drought in
northern Minnesota. Greater than 95% of sulfur in each peat
sample was in an organic form making traditional, wetchemical sulfur fractionation methods uninformative about a
large portion of the total sulfur pool. As an alternative, sulfur
speciation in peat was measured at the micron scale by X-ray
fluorescence mapping at six incident energies spanning the
sulfur 1s absorption edge. Composite maps were fit with
reference spectra. X-ray absorption spectroscopy is being
used to verify sulfur speciation maps. At naturally occurring
sulfur levels, we are able to obtain high quality data. Our goal
is to develop a data analysis protocol providing quantitative,
spatially resolved sulfur speciation.
[1] Urban et al. (1989) Biogeochem 7, 81-109. [2] Gilmour et
al. (1992) Environ. Sci. Technol. 26, 2281-2287. [3] Eimers et
al. (2007) Environ. Monit. Assess. 127, 399-407.
Mineralogical Magazine
Magma degassing timescales from
vesicle size distribution and
bubble composition heterogeneity
in MORB glasses
A. COLIN, P. BURNARD AND B. MARTY
CRPG-CNRS, 15 rue Notre Dame des Pauvres, 54500
Vandoeuvre-lès-Nancy, France
Vesicle size distributions (VSD), the number of bubbles of
a given size plotted against the size interval are classically
used to model the growth rate of vesicles by assuming
continuous vesicle nucleation and growth (as for crystal size
distributions [1]). However, VSD data in MORB samples are
sparse, due to the difficulty in making representative
measurements in low vesicle density samples. Here, we use
direct 3D images in order to calculate vesicle sizes and their
distributions.
The images were obtained by X-ray microtomography
(resolution of 5µm or less) of small pieces (some mm3) of
glassy pillow lava rims sampled along the mid-Atlantic ridge
and the East Pacific Rise. The observed trends allow us to
discuss several key issues such as the duration of the vesiclemagma segregation and the link between magma initial
volatile content and the vesicle growth rate. Atlantic MORBs
and Icleandic glass samples show VSDs that have a distinct
kink in the VSD at 100 – 200 µm micron vesicles, showing
that there are (at least) two different episodes of vesicle
generation: smaller vesicles result from decompression during
the final stages of eruption while larger bubbles likely
represent magma chamber processes. Vesicle-poor samples
such as those from the East Pacific Rise tend to only have a
single episode of vesicle generation.
In order to constrain these degassing processes, the
trapped glass vesicles were subsequently opened by laser
ablation and their volatile contents (He, Ar, CO2) analysed
vesicle by vesicle. The different vesicles preserved in the final
glass nucleated at different stages in the magma history, and
thus preserve more or less degassed stages of the magmatic
volatile evolution. In some samples, the analysed vesicles
have homogeneous compositions, while other samples show
systematic inter bubble variations consistent with a solubilitycontrolled Rayleigh distillation. There is no evidence for
kinetic fractionation of volatiles in the majority of our
samples. These key observations allow the degassing
mechanisms to be modeled, as well as the timescales involved
in the preservation of such millimetric heterogeneities.
[1] Marsh, B. D. (1988) Contrib. to Mineralogy and Petrology
99, 277-291
www.minersoc.org
Goldschmidt Conference Abstracts
Generation of HIMU and EM-1
reservoirs by CO2-fluxed lower
mantle melting: Implications for
OIBs, kimberlites and carbonatites
K.D. COLLERSON1,2*, Q. WILLIAMS3, A.E. EWART1 AND
D. MURPHY4
Earth Sciences, Univ. Queensland, Brisbane, Qld, 4072,
Australia (*correspondence:[email protected])
2
Murrumbo Rare Metals Ltd. Box 1271, New Farm, Qld,
4005, Australia
3
Earth and Planetary Sciences, UCSC, Santa Cruz, California,
95064, U.S.A
4
Biogeosciences, QUT, Brisbane, Qld, 4000, Australia
1
A New Paradigm
P/D isotope ratios of enriched mantle (EM) and high-µ
(HIMU) reservoirs sampled by OIBs, CFBs, kimberlites and
carbonatites are produced by CO2-fluxed lower mantle (LM)
melting [1]. Our model resolves the long-standing conjecture
regarding the formation of HIMU and EM.
Modelling and Implications
Using measured or inferred partition coefficients, we show
that U/Pb, Rb/Sr, Sm/Nd, Lu/Hf, and Re/Os ratios of EM are
associated with C-rich melts while residues evolve to HIMU
[1]. LM melting occurs in thermochemical upwellings by
carbonate suppression of the liquidus. End-members originate
in domains isolated from whole mantle convection. Melts
with > 1% CO2 and residues are variably buoyant allowing
spatial separation of EM and HIMU. HIMU is a refractory
residue with long LM residence time and thus it evolves to
extreme isotopic compositions. EM is a melt that reacts with
ambient mantle and does not produce such extreme isotope
ratios. Entrainment in plumes transports EM and HIMU
domains at different ascent rates to magmagenetic zones at the
top of the LM and in the transition zone.
HIMU does not involve hydrothermally altered oceanic
crust, and EM does not require entrainment of continentderived sediment. Generating EM and HIMU by a single
melting process from pristine mantle explains the presence of
primitive rare gas end-member isotope ratios in mantle plume
magmas as well as constraints of the Pb isotope paradoxes.
Carbon in the deep mantle clearly plays an important role in
Earth’s geochemical evolution. Kimberlites, carbonatites and
OIBs all preserve an isotopic record of their LM pedigree.
Ferric iron geometry and
coordination during hydrolysis and
ferrihydrite precipitation
R.N. COLLINS1,2,*, A.L. ROSE3, C.J. GLOVER4,
D.D. BOLAND1, T.E. PAYNE1,2 AND T.D. WAITE1
School of Civil and Environmental Engineering, The
University of New South Wales, Sydney, NSW 2052,
Australia. ([email protected])
2
Institute for Environmental Research, Australian Nuclear
Science and Technology Organisation, Locked Bag 2001,
Kirrawee DC, NSW 2232, Australia.
3
Southern Cross Geoscience, Southern Cross University, PO
Box 157, Lismore, NSW 2480, Australia.
4
X-ray Absorption Spectroscopy Beamline, Australian
Synchrotron Company Ltd, 800 Blackburn Rd, Clayton,
VIC 3168, Australia.
1
Definitive structural characterisation of ferrihydrite has
challenged scientists primarily due to its nanosized particles
and inherent long-range structural disorder which challenges
analytical methodology (and modelling) typically employed to
determine the structure of minerals. Here we report on the
application of a synchrotron quick-scanning X-ray absorption
spectroscopy (XAS) approach, which allows the collection of
Extended X-ray Absorption Fine Structure (EXAFS) spectral
data to k = 15 Å-1 in < 1 minute, to obtain unparalleled iron Kedge data on the hydrolysis of FeIII(H2O)6 and ferrihydrite
precipitation.
Modelling of the pre-edge and EXAFS data: 1) supports
theoretical studies which have suggested the existence of a
monomeric penta-coordinated FeIII hydrolysis species and;
2) corroborates recently proposed structural models of
ferrihydrite that contain tetrahedral FeIII. Modelling results
indicate that ferrihydrite consists of 15 to 25 % tetrahedral
FeIII and suggest that this geometry must be included in any
comprehensive structural model of ferrihydrite and,
furthermore, should be considered when evaluating the
reactivity, stability and other structure-property relationships
of this mineral.
[1] Collerson et al., (2010) PEPI, 181, 112-131.
Mineralogical Magazine
689
www.minersoc.org
Goldschmidt Conference Abstracts
690
Microbial uptake and methylation of
dissolved elemental mercury
An integrated approach to estimate
the U and Th content of the Central
Apennines continental crust
MATTHEW COLOMBO*, TAMAR BARKAY,
JOHN R. REINFELDER AND NATHAN YEE
School of Environmental and Biological Sciences, Rutgers
University, New Brunswick, NJ, USA
(*correspondence: [email protected])
Introduction
Mercury [Hg] bioaccumulation in fish is critically
dependent on the conversion of inorganic Hg to
methylmercury [MeHg]. In aquatic ecosystems, Hg is
primarily methlyated by anaerobic sulfate- and iron-reducing
bacteria. These microbes are known to methylate mercuric Hg
[Hg2+] to form MeHg. The formation of dissolved elemental
mercury [Hg0(aq)] is thought to limit the concentration of Hg
available for methylation. However, the uptake and
transformation of Hg0 by anaerobic bacteria has never been
tested. Here, we conducted experiments to determine if the
sulfate-reducing bacterium Desulfovibrio desulfuricans
ND132 and the iron-reducing bacterium Geobacter
sulfurreducens PCA can produce MeHg when provided with
Hg0(aq) as their sole mercury source.
Materials and Methods
Strains PCA and ND132 were grown to exponential phase
and subsequently exposed to a constant source of Hg0(aq) under
strict anaerobic conditions. Heat-killed cells (80°C for 30
min), bacterial exudates (growing culture passed through a 0.2
!m filter), and sterile medium were incubated under identical
conditions. Samples were acidified and frozen for MeHg
analysis and purged with N2 gas at ~800 mL/min to remove all
volatile Hg0(aq) prior to total Hg analysis.
Results and Discussion
After ~24 h of exposure to Hg0(aq), strains PCA and ND132
converted Hg0(aq) to non-purgeable total Hg at rates of ~30
!g/L/d and ~1500 !g/L/d, respectively. Control experiments
conducted with heat-killed cells, bacterial exudates, or sterile
medium could not account for the Hg retention, suggesting an
active role by the microorganisms. When provided with Hg0(aq)
as the sole mercury source, strains PCA and ND132 produced
MeHg at rates of ~0.2 !g/L/d and ~0.3 !g/L/d, respectively.
These experimental results indicate that iron-reducing and
sulfate-reducing bacteria are able to uptake and methylate
elemental Hg. The implications of this process in the
terrestrial mercury biogeochemical cycle will be discussed.
Mineralogical Magazine
M. COLTORTI1, R. BORASO1, F. MANTOVANI1,2,
M. MORSILLI1, G. FIORENTINI 1,2 AND G. RUSCIADELLI3
Earth Sciences Department, University of Ferrara
Physics Department, University of Ferrara
3
INFN, Ferrara Section
4
Earth Sciences Department, University of Chieti
1
2
A study for estimating the Th and U content of Central
Italy continental crust was undertaken for evaluating the geoneutrino flux, which is currently measured through Borexino
experiment at LNGS (Laboratori Nazionale Gran Sasso).
Three main layers were identified: Sedimentary Cover, Upper
Crust and Lower Crust, only the first one outcropping in the
Gran Sasso area. Sampling of the other two layers was
performed in the Valsugana area and in the Ivrea-Verbano
zone, assuming rock abundances and composition of the south
Alpine basement fairly homogeneous.
U and Th abundances of the main lithotypes belonging to
the Mesozoic and Cenozoic were grouped into four main
"Reservoirs" based on similar paleogeographic conditions and
mineralogy. Irrespective of magmatic or metamorphic origin
Upper and Lower Crust lithotypes were also subdivided into a
mafic and an acid reservoir, with comparable U and Th
abundances. Based on geological and geophysical properties,
relative abundances of the various reservoirs were calculated
and used to obtain the weighted U and Th abundances for each
of the three geological layers. Using the available seismic
profile as well as the stratigraphic records from a number of
exploration wells, a 3D modelling was developed over an area
of 2°x2° centered at LNGS. This allows to determine the
volume of the various geological layers and eventually
integrate the Th and U contents of the whole crust beneath
LNGS.
On this base the local contribution to the geo-neutrino flux
was calculated and added to the contribution given by the rest
of the world. This new calculation predicts a geoneutrino
signal at Borexino detector about 4 TNU lower than that
previously obtained based on general, worldwide assumptions.
The considerable thickness of the sedimentary rocks, mainly
represented by U- and Th-poor carbonate, is responsible for
the difference. These results suggest that worldwide average
of continental crust cannot be extrapolated to young terrains
without taking into account composition and thickness of
lithotypes within the Sedimentary Cover.
www.minersoc.org
Goldschmidt Conference Abstracts
U-Pb perovskite ages of kimberlites
from the Rosário do Sul cluster:
Southern Brazil
R.V. CONCEIÇÃO1, C. LENZ2, C.A.S. PROVENZANO3,
A. SANDER3 AND F.V. SILVEIRA3
UFRGS-Brazil; ([email protected])
2
UFS-Brazil, ([email protected])
3
CPRM-Brazil, ([email protected];
[email protected]; [email protected])
1
The age of the Rosário do Sul kimberlitic magma is first
presented here. The Rosário do Sul kimberlitic cluster is
located in the southwestern part of the Rio Grande do Sul state
(Southernmost Brazil). This cluster is composed of many
pipes, dikes and sills intruding the Paraná Basin sedimentary
rocks. The Rosário do Sul kimberlites are composed of
macrocrystals and fenocrystals of olivine in a fine grained
matrix which consist of serpentine, phlogopite, carbonate,
spinel, perovskite, apatite and zircon. Xenoliths of peridotitic
rocks of variable sizes were found (1 mm to 5 cm) immersed
in the matrix. The dating of the kimberlite has been conducted
using perovskite, which is found in the matrix and do not
show any inheritance records, which relates it to a primary
magmatic origin. In situ LA-ICP-MS analyses were performed
at the Isotopic Laboratory at UFRGS in a Neptune equipment.
Zircon standard GJ-01 was used, due to the absence of
perovskite standart in the LGI. The laser was set up to produce
a 30 µ diameter spots with a ~0.5 mJ/pulse output energy. The
data reduction was performed using an Excel spreadsheet
program from the University of Brasília, Brazil. The ages were
plotted in a Concordia Diagram, which yield lower intercept
U-Pb ages of 128 ± 5 Ma (MSWD of 3.4). This age is very
close to that of the Parana Flood Basalts, which is assumed as
~130 Ma. Such new data suggest a very complex and
heterogeneous mantle and the occurrence of a great
geothermal variation underneath South America, on the region
of Parana Flood Basalts.
Mineralogical Magazine
691
Contrasting roles of continental and
oceanic arcs in the growth of
continents
K.C. CONDIE1* AND A. KROENER2
Dept of Earth & Environmental Science, New Mexico Tech,
Socorro, NM 87801 USA
(*correspondence: [email protected])
2
Institut für Geowissenschaften, Universität Mainz, 55099
Mainz, Germany ([email protected])
1
Oceanic arcs (OAs) are commonly cited as the primary
building blocks of continents, yet there are many lines of
evidence that continental arcs (CAs) are more important in this
regard. Modern OAs are mostly subducted and lithosphere
buoyancy considerations show that OAs with crust <20 km
thick should completely subduct. Analysis of terranes
indicates that <10% of post-Archean accretionary orogens
comprise accreted OAs, whereas CAs comprise 40-80%.
OA felsic igneous rocks are depleted in incompatible
elements compared to upper continental crust (UC) and have
lower La/Yb and Sr/Y ratios, whereas those produced in CAs
are similar in composition to UC. Nd and Hf isotopic ratios
suggest that accretionary orogens comprise 40-65% juvenile
crustal components and that >50% of these components are
produced in CAs.
These observations present a paradox: older continental
crust is necessary for the production of new continental crust.
As indicated by Th/Yb, Nb/Yb, and Nb/Yin greenstone
volcanics, CAs did not become widespread until after the late
Archean. Prior to 2.5 Ga, OAs may have been more difficult
to subduct due to a hotter mantle, and together with oceanic
plateaus, they may have contributed to the construction of
Archean continents. After this time, however, the production
site of continental crust shifted to CAs, and most OAs were
subducted.
www.minersoc.org
692
Goldschmidt Conference Abstracts
Synthetic ‘age solutions’ reference
materials for U-Th geochronology
DANIEL J. CONDON1, GIDEON HENDERSON2,
DAVID A. RICHARDS3 AND JON WOODHEAD4,
NERC Isotope Geoscience Laboratory, British Geological
Survey, UK
2
Department of Earth Science, Oxford University, UK
3
School of Geographical Sciences, University of Bristol, UK
4
School of Earth Sciences, University of Melbourne, Australia
1
Over the past 15 years there has been considerable
improvement in our ability to measure U and Th isotope ratios
and concentrations resulting in a reduction of U-Th age
uncertainties by an order of magnitude (age uncertainties are
now as low as 0.1%). The accuracy of these dates is
dominated by (1) the U/Th tracer calibration; (2) mass
spectrometry, (3) various corrections applied, and (4)
‘constants’ used in the age calculation (secular equlibrium and
decay constants, the 235U/238U value of natural U etc.). Some of
these parameters can be considered as ‘systematic’ (i.e., decay
constant uncertainties) and others either contain a random
component or are systematic but ‘laboratory’ specific (such as
tracer calibration).
At present inter-laboratory agreement and intra-laboratory
long-term external reproducibility of U-Th Isotope Dilution
Isotope Ratio Mass Spectrometry data is assessed through
analyses of natural cabonate ‘standards’. Though powdered
carbonates standard zircons are ideal for assessing the total
system (dissolution, purification via anion echange chemistry
and mass-spectrometry), these are limited in supply and not
widley avaibalbe limiting their use for asessing interlaboratory agreement. Here we outline a proposal and the
initial steps taken for the development the development and
calibration of a series of synthetic U-Th ‘age solutions’
prepared by mixing different amounts of high-purity monoisotopic solutions (234U, 230Th etc.) in proportions that mimic
commonly analysed materials (e.g., a last-interglacial
speleothem) so that their analyses closely replicates the
analytical protocols employed on normal samples. We believe
these solutions will augment natural carbonate standards as a
means of interlaboratory comparsion and assessment of longterm external reproducibility, and as such are intended for
community use and will be made available.
The
intercalibration project is part of a broader community effort
that has developed out of the PALSEA and EARTHTIME
initiatives.
Measuring the isotopic composition
of small (<5 ng) U samples by
MC-ICP-MS
J.N. CONNELLY AND M. BIZZARRO
Centre for Star and Planet Formation, State Natural History
Museum of Denmark, Øster Voldade 5-7, 1350
Copenhagn K, Denmark.
Pb-Pb ages have been based on Pb isotopic measurements
while assuming that the 238U/235U ratio is constant at 137.88.
Using a second-generation multi-collector inductively coupled
plasma mass spectrometer (MC-ICP-MS), [1] has documented
3400 ppm variability in the 238U/235U ratios of calciumaluminum-rich inclusions (CAI) in chondrites [1],
corresponding to a 5 Myr deviation in calculated Pb-Pb ages.
This makes clear the need to measure the U isotopic
composition of all meteorites and their components when
determining their
Pb-Pb ages. The challenge lay in
developing analytical protocols to measure the isotopic
composition of typically small samples of U (<5 ng)
sufficiently precisely to be useful in constraining events that
occurred in the first 10 million years of the solar system. With
100 ppm uncertainty corresponding to 0.15 Myr, we must
achieve less then 200 ppm uncertainty on 238U/235U ratios. We
have developed a three stage chemistry starting with
Eichrom’s UTEVA resin followed by two progressively
smaller anion columns that effectively isolates U from the
sample matrix elements. U is measured using an Aridus II
desolvating nebulizer on a ThermoFisher Neptune with the Jet
Cone Interface, a configuration that delivers '2500 V of signal
per 1 ppm concentration of U. Running with an uptake rate of
0.15 ml/min, we analyze 5 ng for a total acquisition time of 15
min with a 235U intensity of ~40 mV. Fractionation correction
for the measured 238U/235U ratio is controlled by the
simultaneous measurement of the synthetic equal-atom 233U236
U tracer IRMM 3636 that was added to samples before
dissolution. Blank correction is determined by bracketing runs
(of equal time as unknown runs) of the 2% HNO3 used to
dissolve samples. CRM 112a spiked with IRMM 3636 is run
as a bracketing standard to monitor within run stability. Using
these methods, we are able to routinely determine the isotopic
composition of small (<5 ng) amounts of U separated from
terrestrial rock standards and doped meteoritic matrices to
better than 200 ppm precision and external reproducibility.
Analyzing meteorites and their components, we have
investigated the 238U/235U variability of the inner solar system.
[1] Brennecka et al. (2010) Science 327, 449-451.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Isotopic evidence for microbial
oxidation of dissolved methane in the
Gulf of Mexico oil spill deep plume
M.E. CONRAD*, M. BILL, W.T. STRINGFELLOW,
S.E. BORGLIN, O.U. MASON, E.A. DUBINSKY,
Y.M. PICENO, J.L. FORTNEY, L.M. TOM,
K.L. CHAVARRIA, R. LAMENDELLA, D.C. JOYNER,
K. WETMORE, J. KUEHL, R. MACKELPRANG, C. WU,
J. LIM, F. REID AND T.C. HAZEN
Earth Sciences Division, E.O. Lawrence Berkeley National
Laboratory, Berkeley, CA 94720
(*correspondence: [email protected])
The blowout of BP’s Macondo well and subsequent
sinking of the Deepwater Horizon drilling platform on April
20, 2010 led to one of the largest oil spills in history. By the
time the well was capped on July 12, 2010, ~4.9 million
barrels of oil are estimated to have leaked into the Gulf of
Mexico. Accompanying this spill was the development of a
deep plume of dispersed oil and dissolved gases at a depth of
1100-1200 mbsl that was detected at distances of up to 35 km
from the wellhead. The #13C values of dissolved hydrocarbon
gases (C1-C5) and BTEX compounds in 77 samples collected
from in and around the deep plume between May 28, 2010 and
August 24, 2010 were analyzed to track the fate and potential
biodegradation of those compounds. C2 to C5 gases and
BTEX compounds were only high enough for #13C analyses in
samples collected before mid-June. The #13C values of these
compounds remained within ±2‰ of #13C values of samples
from the Macondo well. CH4 concentrations in early plume
samples (collected before mid-June) were as high as 300 µM,
but dropped off significantly in later samples. The #13C of
CH4 in the early samples were between -57‰ and -59‰
compared to an average #13C value of -58‰ for samples from
the Macondo reservoir. After mid-June, CH4 from some of the
samples had higher #13C values. The last two CH4 samples
with measurable #13C values were collected during early
August, 3 weeks after the well was capped and had #13C
values of -44‰ and -23‰. For a fractionation factor of 0.984
for microbial oxidation of CH4, those values indicate 60% and
90% oxidation of the methane, respectively. These samples
coincided with drops in the dissolved oxygen concentrations
in the water column of ~1.5 mM also suggesting increased
aerobic microbial activity. In addition, the #13C values of
bacterial phospholipids extracted from a single sample were
lower than normal background biomass, suggesting that the
bacteria were consuming CH4 and other hydrocarbons with
lower #13C values than the background organic matter.
Mineralogical Magazine
693
Dynamics of the Pliocene East
Antarctic Ice Sheet revealed by
isotopes in marine sediments
C. COOK1*, T. VAN DE FLIERDT1, T. WILLIAMS2,
S. HEMMING2 AND E.L. PIERCE2
Imperial College London, London, UK, SW7 2AZ
(*correspondance: [email protected])
2
LDEO, Palisades, NY 10964-1000 USA
1
Our understanding of the dynamics of the East Antarctic
Ice Sheet (EAIS) during the climatically warm early Pliocene,
and the transition to the cooler, but more variable late
Pliocene, is limited. Integrated isotope analyses of detrital
marine sediments from ODP Site 1165 (64˚22-77S, 67˚1314E), Prydz Bay, East Antarctica, offer novel insights into the
evolution of the East Antarctic Ice Sheet, and reveal the
controls on sediment composition in a glacial environment.
Here we investigate the 40Ar/39Ar ages of hornblende grains
from ice-rafted detritus (IRD) (>150µm) and neodymium and
strontium isotope fingerprints of detrital marine sediments
(<63µm).
Early Pliocene sediments, deposited between 5.0 and 3.5
Ma, are dominated by hornblende IRD grains typical of the
local Prydz Bay region (40Ar/39Ar ages of ~500 Ma). However,
fine-grained (<63 µm) material exhibits #Nd values of -14,
untypical of modern marine sediments in this area (#Nd: -17 to
-19). The source of these higher #Nd values could be either the
nearby Mawson coast (#Nd: ~-15- to -14) or the distal Wilkes
Land margin (-12.3 to -14.8), with sediments carried by
bottom currents. Strontium isotopes, however, are more
radiogenic than expected, an observation that could either be
due to sedimentary sorting, continental weathering, or subtle
shifts in provenance affecting Rb/Sr rations. Conversely, Late
Pliocene sediments with depositional ages of 3.3 to 2.8 Ma
display an increase in distally sourced Wilkes Land IRD
(40Ar/39Ar ages of 1100-1300 Ma). The IRD provenance signal
is positively correlated to detrital 87Sr/86Sr and #Nd signatures
in the fine fraction of the same samples, indicating an
increasing amount of material derived from the distal Wilkes
Land margin (#Nd: -12.3 to -14.8; 87Sr/86Sr: 0.730-0.735). Our
results imply that ice rafting played an important control on
sediment composition in the late Pliocene, possibly related to
the growth of the EAIS in a cooler Late Pliocene climate.
Overall, the radiogenic isotope composition of
Pliocene detrital sediments in the Southern Ocean reflects
changing environmental conditions as well as sedimentary
processes. Interpretation of such data can provide a valuable
framework for the interpretation of ice sheet instability events
along the Antarctic continental margin.
www.minersoc.org
Goldschmidt Conference Abstracts
694
Systematic tapping of independent
magma chambers during the 1 Ma
Kidnappers supereruption
Distinguishing between open and
closed system magma differentiation
at arc volcanoes by combining
U-series and elemental systematics
G.F. COOPER*, C.J.N. WILSON AND J.A. BAKER
L.B. COOPER12*, O. REUBI1, M. DUNGAN2,
B. BOURDON3 AND C.H. LANGMUIR4
SGEES, Victoria University, PO Box 600, Wellington, NZ
(*correspondence: [email protected])
The 1.0 Ma Kidnappers eruption (~1200 km3 bulk
volume) from Mangakino volcanic centre produced the largest
phreatomagmatic fall deposit in New Zealand, followed by the
most widespread ignimbrite on Earth [1]. Samples collected
through a proximal 4.0 m section of the Kidnappers fall
deposit, representing the first 60-70 % of erupted material,
reveal multiple, independent magma chambers of comparable
size were tapped during the eruption. Evidence for this
includes the following: (i) Major and trace element
chemistries of individual matrix glass shards define three glass
populations (types A, B and C), which display a systematic
change through the fall deposit. (ii) Plagioclase, hornblende
and Fe-Ti oxide compositions show bimodal distributions,
corresponding to type A and B glass compositions, with a
minor tail corresponding to C. (iii) Type B glass shards and
biotite first appear at the same level in the fall deposit
suggesting the later tapping of a biotite-bearing magma. (iv)
Compositional gaps between glass types A and B imply that
no mixing between these magmas occurred.
Parallel covariant trends in glass trace element chemistry
indicate at least two independent magmas (A, B) underwent a
parallel evolution with respect to crystallizing plagioclase and
zircon. Temperature and pressure estimates from hornblende
and Fe-Ti oxide equilibria from each magma type show that
the two magma chambers were similar and therefore adjacent,
not vertically stacked, in the crust. Hornblende temperature
and pressure estimates from magmas A and B range from 770
to 860°C and 90 to 220 MPa corresponding to magma
chamber depths of ca. 4 to 8 km. Hornblende pressure
estimates coupled with in situ trace element fingerprinting
imply that a horizontal stratification was also present in both
of the A and B magma chambers. Pumice glass analyses from
the subsequent ignimbrite display a broader compositional
range than the fall deposits indicating the discharge of
magma(s) that are not represented earlier in the eruption. This
work has implications for understanding the dynamics of large
(‘super‘) volcanic events and how such large volumes of
silicic magmas are generated, stored and erupted.
[1] Wilson et al. (1995), Nature 378, 605-607.
Inst. of Geochemistry and Petrology., ETH Zurich,
Switzerland
(correspondence: [email protected])
2
Sect. of Earth Sciences, Univ. of Geneva, Switzerland
3
Ecole Normale Supérieure de Lyon and CNRS, France
4
Dept. of Earth and Planetary Sciences, Harvard Univ., USA
1
Constraining crustal assimilation in volcanic arcs is
important because crustal components can be added during
both mantle melting and magma ascent. Reubi et al. [1]
present evidence for up to 10-15% assimilation of crust at
Volcán Llaima (38.7°S), Chilean Southern Volcanic Zone,
resulting in a diminution of U-series excesses from mantle
signatures towards U-rich plutonic endmembers on the
equiline. These trends strongly correlate with trace element
indices of contamination over 51-57 wt% SiO2. Llaima is now
a very well-characterized volcano with respect to U-series
activity ratios (U-Th-Ra-Pa), with 28 historic samples selected
from >180 on the basis of major and trace elements. These
data will be used to model differences in magma evolution in
seven historic eruptive episodes (1640-2009).
In order to evaluate along-arc variations in crustal
contributions, we have analyzed five selected samples from
nearby Volcán Lonquimay (30 km NE of Llaima, 38.4°).
Major and trace element variations over 52-63 wt% SiO2
provide much less evidence for open-system processes than
that recorded by the more contaminated Llaima samples
(Rb/Zr=0.12-0.31 at Llaima versus 0.14-0.17 at Lonq.). Useries activity ratios for Lonquimay are constant and overlap
with the least contaminated Llaima samples. And, simple
equilibrium phenocryst assemblages in the Lonquimay lavas
suggest that magma evolution is controlled almost exclusively
by closed-system crystal fractionation. The cause of the
Llaima/Lonquimay contrast remains unclear. Llaima is larger
and more active than Lonquimay, perhaps leading to a higher
efficiency of assimilation.
With the further constraints provided by U-series, greater
quantitiative understanding of the extent and causes of crustal
contamination will become possible. Much of the earlier data
from southern Chile may need to be re-evaluated. More Useries studies are currently underway at Nevados de Chillán
(36.8°), Antuco (37.3°), Villarrica (39.5°), and Osorno (41°).
[1] O. Reubi et al. (2011) Earth Planet Sci Lett 303, 37-47.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
U-Pb geochronology of the Southern
Scandinavian Caledonides:
The Mesoproterozoic Espedalen
anorthosite-gabbro-norite massif and
associated rocks
Nuclear imaging of 99mTc transport
and immobilisation through porous
media
CLAIRE L. CORKHILL1*, JONATHAN W. BRIDGE1,
PHILIP HILLEL2, CLAIRE UTTON3, NEIL C.HYATT3,
STEVEN A. BANWART1 AND
MARIA ROMERO-GONZALEZ1
F. CORFU1 AND M. HEIM2
University of Oslo, Dept. Geosciences PB 1047 Blindern, N0316 Oslo, [email protected]
2
The Norwegian University of Life Sciences (UMB), PB 5003,
N-1432 Aas, ([email protected])
1
Exactly 100 years ago V.M. Goldschmidt completed his
PhD thesis on contact metamorphism in the Oslo Graben, and
shifted attention to the Caledonian mountains and their
problems concerning tectonics, metamorphism and
magmatism. Based on these studies, in 1916 he provided a
detailed description of the two main plutonic suites that occur
in the nappes, the anorthosite-charnockite series and the
contrasting opdalite-trondhjemite series. He outlined the main
features of the rocks and discussed many of the fundamental
question concerning these suites, their relationships, ages,
origin and processes controlling their formation. Interestingly,
and in spite of the enormous progress in many fields, many of
the problems discussed in his paper remain relevant and
unsolved today, a century later. In our present study we deal
with an anorthosite massif and associated rocks in the easternmost part of the Jotunheimen mountains investigated by
Goldschmidt. One basic question concerns the relationship
between these rocks and the major other anorthositic domains
in the Jotunheimen and Bergen regions, and the relationships
between the various members of the suite including the out of
order sequence of crystallization of anorthosite and other
mafic to intermediate rocks. Zircon found in coarse grained
noritic anorthosite in Espedalen indicates an age of about 1520
Ma, similar to, or slightly younger than those for tonalite and
granite in the supposed metamorphous sub-volcanic complex
at the interface with tectonically underlying psammitic rocks.
Zircons from a lamprophyre dyke yields an age of 1514 Ma.
The U-Pb data also record partial disturbances during the
Sveconorwegian orogeny, a feature typical of most rocks of
the Jotun Nappe Complex. The age of 1520 Ma for the
Espedalen massif shows that this intrusion is clearly distinct
from the Sveconorwegian anorthosite (ca. 965 - 970 Ma) in
the Jotun and Lindås nappes. The 1500 Ma event correlates
instead with the very intense activity that build much of the
south-Norwegian crust, thus supporting a provenance of the
nappe from southern Baltica.
Mineralogical Magazine
695
Kroto Research Institute, Department of Civil and Structural
Engineering, University of Sheffield, S3 7HQ, UK.
(*corresponding author: [email protected])
2
Department of Nuclear Medicine, Hallamshire Hospital,
Sheffield, S10 2JF, UK
3
Department of Materials Science and Engineering, University
of Sheffield, S1 3JD, UK
1
99
Tc is a <-emitting radioactive fission product of 235U,
formed in nuclear reactors. Its long half life (2.1x105 years)
and high environmental mobility in oxic conditions as the
pertechnetate anion (Tc(VII)O4) presents a major challenge to
nuclear waste disposal strategies.
We demonstrate non-invasive quantitative imaging of the
transport of 99mTc, a J-emitting metastable isomer of 99Tc
commonly used in medical imaging. Transport of this
radionuclide was measured during co-advection through
quartz sand and various cementitious materials commonly
used in nuclear waste strategies, including crushed ordinary
portland cement (OPC), OPC combined with blast furnace
slag (BFS) or pulversised fly ash (PFA), and Nirex Reference
Vault Backfill material. Pulse-input experiments of
approximately 25MBq 99mTc were conducted under saturated
conditions and at a constant flow of 0.33ml/min. Dynamic
gamma imaging was conducted every 30s for 2 hours.
Relative changes in mass distribution of 99mTc over time
were quantified by spatial moments analysis of the resulting
plume. 99mTc advected through quartz sand and crushed OPC
demonstrated typical conservative behaviour, while transport
through BFS- and PFA-containing cements produced a
significant reduction in colloid centre of mass transport
velocity over time. We propose that this is likely due to
reduction of 99mTc by active reducing agents such as Fe and S
in the cementitious material. Concurrent batch experiments
using 99Tc demonstrated the relatively irreversible sorption of
Tc to these materials.
Gamma camera imaging has proven an effective tool for
helping to understand the factors which control the migration
of radionuclides for surface, near-surface and deep geological
disposal of nuclear waste.
www.minersoc.org
696
Goldschmidt Conference Abstracts
Pedogenesis and stabilization of soil
organic carbon in a charcoal
production plot
Spectral Gamma-ray applications to
marine organic-rich sediments of the
Lower Jurassic of Portugal
JEAN-THOMAS CORNELIS*, BRIEUC HARDY, BRUNO
DELVAUX AND JOSEPH DUFEY
Earth and Life Institute – Environmental Sciences, Université
catholique de Louvain, Louvain-la-Neuve, Belgium
(*correspondence: [email protected])
Charcoal addition to soil has the potential to improve
physical, chemical and biological functions of soil [1], while
being used as a potential long-term sink for atmospheric CO2
due to the intrinsic recalcitrance of aromatic components [2].
Our hypothesis is that production process and addition of
charcoal in soil can influence the pedogenic processes
governing the soil capacity to stabilize organic carbon (OC).
The experimental site is located in an oak forest in the
loessic silt belt of Belgium. The well-drained and acidic (pH
3.8-4.3) soil is classified as a Luvisol with an argic horizon
occurring at 30 cm depth. We carried out the mineralogical
and physico-chemical analysis (i) in an ancient charcoal
production plot (1750-1870), and (ii) in the reference forest
soil. Moreover, we analyzed the content of labile and stable
(mineral-protected and recalcitrant) OC in charcoal-enriched,
organo-mineral (Ah), eluvial (E) and argic (Bt) horizons.
The soil-pH increases by 0.6-0.8 units and the base
saturation is until eight fold higher after the addition of
charcoal. In the eluvial E horizon just below the charcoal
accumulation, we observe a slight decrease of the content of
amorphous and crystalline iron oxides, which provide reactive
hydroxylated surfaces for OC associations. The mass of stable
OC per unit area in the soil below the ancient charcoal
production plot is significantly higher (13.9 kg.m-K) than in the
reference Luvisol (5.8 kg.m-K). Charcoal, as residues of slow
pyrolysis, strongly increases the sequestration of C in soil
through (i) intrinsic recalcitrance and (ii) charcoal-organomineral interactions. Indeed, the part of humified, dissolved or
colloidal OC released from charcoal and stabilized upon
silicates and oxy-hydroxydes is not negligible (5.6 kg.m-K).
Finally, the pedological modifications induced by the charcoal
production process do not significantly influence the stable
OC stock. Therefore, the addition of charcoal will lead to
higher C sequestration in topsoil without affecting the subsoil
capacity to stabilize OC.
[1] Glaser B., Lehmann J. & Zech (2002) Biology and Fertility
of Soils 35, 219-230. [2] Baldock J. & Smernik R. (2002)
Organic Geochemistry 33, 1093-1109.
Mineralogical Magazine
G.G. CORREIA1*, L.V. DUARTE1, A.C. PEREIRA1,
R.L. SILVA1AND J.G. MENDONÇA FILHO 2
Universidade de Coimbra, Departamento de Ciências da
Terra and IMAR-CMA, 3000-272 Coimbra, Portugal
(*correspondence: [email protected])
2
IGEO and LAFO, Universidade Federal do Rio Janeiro,
21949-900 Rio de Janeiro, Brazil
1
This study is based on a high-resolution gamma ray
analysis, performed on the hemipelagic Lower Jurassic
organic-rich unis of the Lusitanian Basin (Portugal). This time
interval, namely the Late SinemurianPliensbachian, is
recognized as one of the most important potential oil source
rock in Portugal [1].
Supported by more than 1000 gamma-ray measurements
from outcrop and laboratory, the obtained data (total GR, Th,
U and K) were correlated with several mineralogical (by XRay diffraction) and geochemical parameters, such as total
organic carbon (TOC), insoluble residue (IR) and sulfur. From
our results, and similarly to other case studies [2], we
emphasize the relation between U and TOC, whose maximum
value reaches 20%. A fair to good correlation is generally
observed between these two variables (Fig. 1), however other
lithological and geochemical (e.g. IR) parameters of the
organic-rich facies may determine some variations.
Figure 1: U/TOC correlation of the studied Lower Jurassic
samples, with the U values obtained in laboratory.
This work has been financially supported by project
PTDC/CTE-GIX/098968/2008 (FCT - Portugal).
[1] Duarte et al. (2010), Geologica Acta 8 (3), 325-340. [2]
Luning & Kolonic (2003), Journal of Petroleum Geology 26,
153-174.
www.minersoc.org
Goldschmidt Conference Abstracts
Deglaciation pattern during the
Late-Glacial / Holocene transition in
the Southern French Alps.
Chronological data from the
Clarée Valley (Durance catchment,
S. France)
ETIENNE COSSART1, DIDIER BOURLES2,
REGIS BRAUCHER2, MONIQUE FORT3, ROMAIN PERRIER3
2
AND LIONEL SIAME
Université Paris 1 Panthéon-Sorbonne, UMR Prodig 8586 –
CNRS, 2 rue Valette, F-75005 Paris,
etienne[email protected]
2
UMR CEREGE 6635 – CNRS, Plateau de l’Arbois, F-13100
Aix en Provence
3
Université Paris Diderot (Paris 7), UMR Prodig 8586 –
CNRS, 2 rue Valette, F-75005 Paris
1
The Southern French Alps, characterized by many climatic
influences, remain a scientific problem for palaeoenvironmental studies. Indeed, the lack of chronological
benchmarks hitherto hampered the definition of sequences of
glacier variations since the Last Glacial Maximum (LGM),
even if a scenario was established in the Ubaye valley. This
scenario was then considered as a regional model by many
geomorphologists, but this valley is not necessarily
representative of the entire region. We focus here on the upper
part of the Durance watershed because it corresponds to the
accumulation zone of the main glacier of the Southern French
Alps during the LGM. Thanks to extensive fieldwork and
geomorphic mapping of remnants of past glaciations, and
thanks to new chronological data (about 35 cosmic ray
exposure –CRE– ages) we propose the first absolute scenario
established in the very upper part of the catchment. To assess
CRE ages, we sampled glacially-polished surfaces, in order to
assess both the retreat of the front and the thinning rate of the
glacial tongue. We also paid attention to morainic ridges and
glacio-fluvial remnants. The results show that cirque
glaciation began only at the beginning of the Holocene, and
that thick valley glaciers still occupied the upper valleys
during the Late-Glacial period, until the Younger Dryas
stadial. The disappearance of the tongue occurred rapidly,
between Younger Dryas and Preboreal sequences due to both
ELA rise and a topographic threshold effect. Finally, this
scenario appears to be well in accordance with new data
obtained in other parts of the Alps.
Mineralogical Magazine
697
The composition of the Earth’s outer
core from first principles
ALEXANDER S. CÔTÉ1,2, JOHN P. BRODHOLT1
2
AND JAMES BADRO
1
2
Dept. of Earth Sciences, University College London, U.K.
Institut de Physique du Globe de Paris, France.
The exact composition of the Earth’s core remains an
unanswered question. Published models for the outer core
allow a mixture of several coexisting light elements (Si, S, O,
C), and many arguments have been put forward over the years
for and against each of those elements.
In this study we performed ab initio molecular dynamics
calculations on liquid Fe and liquid Fe-(Si,S,C,O) mixtures at
different P and T conditions of the Earth's outer core in order
to attempt to constrain the light-element concentration based
on densities and bulk sound velocities. By fitting equations of
state to our P-V data, we were able to obtain density and
velocity vs. concentration profiles for each iron-light-element
liquid alloy; this allowed us to estimate the density for
different outer core compositions found in the literature and
compare them with seismic models such as PREM and
AK135. We find that the density of liquid Fe containing 4% of
Ni (no light elements) is approximately 7% denser than the
core. Incorporating light element increases the bulk sound
velocity while decreasing density. We also find that many of
the published compositional models for the outer core result in
densities lower than the seismological models. This indicates
that the light element concentrations predicted in those models
are slightly overestimated. Our data agree with an O-rich outer
core (up to 6.3wt. %), and we find that large amounts (more
than 3 wt. %) of Si cannot be incorporated in the outer core.
www.minersoc.org
698
Goldschmidt Conference Abstracts
Zn isotope fractionation in the
soil-plant system (a pot experiment)
Early fossilization process of
cyanobacteria in modern
microbialites
E. COUDER1*, T. DROUET2, B. DELVAUX1,
C. MAERSCHALK3, C. MEEUS3 AND N. MATTIELLI3
Earth and Life Institute – Environmental Sciences – Science
Soil, Université catholique de Louvain, Croix du Sud,
2/10, 1348 Louvain-la-Neuve, Belgium
(*correspondence: [email protected])
2
Laboratoire d’Ecologie végétale et Biogéochimie, Université
Libre de Bruxelles, 1050 Brussels, Belgium
3
Département des Sciences de la Terre et de l’Environnement,
Université Libre de Bruxelles, 1050 Brussels, Belgium
ESTELLE COURADEAU1,2, KARIM BENZERARA1,
EMMANUELLE GERARD2, IMENE ESTEVE1,
DAVID MOREIRA3 AND PURIFICACION LOPEZ-GARCIA3
1
Zinc isotopes constitute a precious tool to trace metal
sources and better understand the cycling of this
micronutriment in the environment. The aim of the present
study is to investigate the Zn isotope fractionation for
evaluating the interaction between plant species and soil types,
in order to better characterize Zn migration through the soilplant system.
Three contrasted soils, originating from a zone with
intense metallurgical activites in Belgium, have been used for
the culture experiment conducted in controlled conditions: a
calcareous soil ($66Znbulk soil = +0.06‰) and an acid shalederived soil ($ 66Znbulk soil = +0.08‰) both essentially feeded by
aerial fallouts, and a slag heap-derived soil ($66Znbulk soil =
+0.37‰). Two plant species have been chosen: a dicot species
(rape) and a monocot species (ryegrass). The Zn isotopic
compositions have been measured in roots ($66Zn = +0.01 to
+0.43‰) and in shoots ($66Zn = -0.23 to +0.28‰).
The results show that (a) the Zn isotopic compositions of
all materials reflect the Zn isotopic signatures of the main Zn
inputs (aerial fallouts vs smelter-slag residues); (b) light Zn
isotopes are preferentially accumulated in shoots; (c) the
magnitude of Zn fractionation during Zn transport from roots
to shoots appears to be related to the cation exchange capacity
of roots (CECR) and the water use efficiency (WUE). The
plant species affects the Zn signature in plant parts through the
density of negative charges in the roots, i.e. CECR being
larger for the dicot species implies a larger Zn isotope
fractionation between shoots et roots. In addition, the WUE
might regulate a form of isotopic selection by controlling the
efficiency of Zn adsorption on cell walls.
In the soil-plant system, enrichment in light Zn isotopes is
favoured into the plants. As Zn is subsequently recycled to the
soils through dead plant material return, the plant cover plays
a key role on Zn fractionation in soils.
Mineralogical Magazine
IMPMC, UMR 7590, UPMC, IPGP & CNRS 4 place Jussieu,
Paris, France ([email protected])
2
Géobiosphère actuelle et primitive UMR 7154, IPGP, UPD &
CNRS, 1 rue Cuvier , Paris, France
3
Ecologie, Systématique et Evolution, UMR 8079 CNRS &
Université Paris-Sud, France ([email protected])
1
Most extant life diversity is microbial. Despite so,
microbes are rarely described in the rock record. Part of the
problem comes from the difficulty to identify microfossils
unambiguously, since they can be morphologically confused
with abiotic biomorphs [1]. Therefore, identifying traces that
can be diagnostic of microbial fossils is crucial. To contribute
to this aim, we studied the ongoing fossilization of
cyanobacterial cells in modern microbialites from Alchichica
Lake (Mexico). Alchichica Lake is a Mg-rich hyperalkaline
crater lake (pH 8.9) containing living stromatolites composed
and
hydromagnesite
of
aragonite
[CaCO3]
[Mg5(CO3)4(OH)2•4(H2O)] [2]. Cyanobacteria comprise most
of the microbialite biomass. Scanning electron microscopy
coupled with confocal laser scanning microscopy were used to
co-localize cyanobacterial cells and associated minerals. These
observations showed that cells from the order Pleurocapsale
become specifically encrusted within aragonite with an
apparent preservation of cell ultrastructures. Early fossilization
gradients from living to totally encrusted cells span distances
of a few hundred micrometers. Cells with increasing levels of
encrustation where observed down to the nm-scale by
transmission electron microscopy performed on Focused Ion
Beam (FIB) ultrathin (<100 nm) foils. Two types of aragonite
crystals differing by their morphology were seen within and
outside cells. Synchrotron-based scanning transmission x-ray
microscopy (STXM) analyses at the C and N K-edges [3]
were performed on the same FIB foils. They provide
information on the evolution of carbon and nitrogen speciation
along this early fossilization gradient. We propose a model of
the early fossilization process of these cyanobacteria and their
associated organic molecules.
[1] Garcia-Ruiz JM & al. (2003) Science 302:1194-7.[2]
Ka!mierczak J & al (2011) Facies 2011:1-28.[3] Bernard S &
al. (2010) GCA 74:5054-68.
www.minersoc.org
Goldschmidt Conference Abstracts
Solid speciation of As, Pb and Sb-rich
anthropogenic residues
S isotopes distinguish two S pulses at
terrestrial Cretaceous-Paleogene
boundary sections
A. COURTIN-NOMADE1*, O. RAKOTOARISOA1, H. BRIL1,
M. KUNZ2 AND N. TAMURA2
University of Limoges, GRESE Laboratory, FST, 123,
avenue A. Thomas, 87060 Limoges Cedex, France
(*[email protected])
2
Advanced Light Source, Lawrence Berkeley National Lab, 1
Cyclotron Rd, Berkeley, CA 94720, USA
M.L. COUSINEAU1*, F. THERRIEN2, T. MARUOKA3,
B.A. WING4 AND D. FORTIN1
1
We studied As, Pb and Sb solid speciation to better
understand the geochemical pathways and mobility of these
potentially toxic elements, which are released upon
weathering of mining and industrial waste products. Such
studies are indispensible to understand soil and water
contaminations and to propose remediation solutions. Studied
samples are mining residues (mill tailings and slags) from the
French Massif Central, generated by former activities over a
century (1830 to 1970). They were collected at two different
mining districts: Pontgibaud, which was one of the largest
production site for Ag and Pb (c.a. 50’000 t Pb) and BrioudeMassiac, which produced around 40’000 t of Sb (second
largest nationwide production). Samples were also studied to
compare the evolution of industrial processes and to test the
variations in Pb or Sb retention.
Mining residues from the two locations show elevated
concentrations in As, Pb and Sb, up to 0.16%, 6.6% and 1.1%
respectively. However spatially concentrated accumulations of
As (up to 11 wt.%), Pb (up to 70 wt%) and Sb (up to 28 wt.%)
are also observed. The mineralogical characterization of the
products with such contents is essential for the modeling of
the geochemical processes controlling the toxicity of these
elements. Arsenic, Pb and Sb have only been detected in
secondary products resulting from oxidation of Pb or Sb-rich
sulfides (galena, stibnite and berthierite) but only few relics of
primary sulfides have been observed. Synchrotron X-ray
microdiffraction (beamline 12.3.2, Advanced Light Source,
USA) and micro-Raman investigations indicate that Sb forms
complex mixing phases with goethite and/or lepidocrocite.
Antimony is also trapped by jarosite suggesting a substitution
of Fe3+by Sb5+ (up to 3% Sb). Antimony is present as oxides,
stibiconite SbSb2O6(OH) and associated with Fe, and possibly
Mn (oxy-)hydroxides within solid phases of highly
heterogenous compositions. Arsenic is also typically
associated to iron (oxy-)hydroxides presenting various
cristallinity. Main Pb host phases are sulfates (e.g., anglesite
Pb(SO4), beudantite Pb(Fe2.54Al.46)(As1.07O4)(S0.93O4)(OH)6) but
Pb is also associated to complex mixing of silicates and Fe
oxides.
Mineralogical Magazine
699
Earth Sciences, University of Ottawa, Ottawa, Ontario,
Canada (*correspondence: [email protected])
2
Royal Tyrell Museum of Palaeontology, Drumheller, Alberta,
Canada ([email protected])
3
Integrative & Environmental Sciences, University of
Tsukuba, Ibaraki, Japan ([email protected])
4
Earth and Planetary Sciences, McGill University, Montréal,
Québec, Canada ([email protected])
1
The Cretaceous-Palaeogene (K-Pg) boundary marks a
major biotic turnover in Earth’s history that may have
resulted, at least in part, from a massive bolide impact.
Two of the northernmost occurrences of the K-Pg
boundary in terrestrial sediments have been positively
identified on the Knudsen’s T. rex Ranch in the Scollard
Formation of south-central Alberta, Canada. We conducted a
high-resolution (2-cm intervals) study of bulk sulfur isotopes
and sulfur content across a ~50-cm stratigraphic interval
spanning the K-Pg boundary, representing a time interval of
~500 Ka.
Figure 1: (34S profiles at the Knudsen’s T. rex Ranch
Positive (34S excursions at both sites reveal a pulse of
S-enriched sulfur at the boundary, likely originating as
oceanic sulfate and evaporite target rocks. Post-boundary #34S
excursions may reflect injection of volcanically-derived
sulfate aerosols; at least one peak (KFS) is contemporaneous
with a major phase of Deccan trap volcanism. Analyses of
minor S isotopes (33S, 36S) offer the possibility to validate our
interpretation of the origins of the boundary and postboundary S injections into the freshwater environment.
34
www.minersoc.org
700
Goldschmidt Conference Abstracts
Copper and zinc isotope fractionation
during their interaction with
phototrophic biofilm
A. COUTAUD1,2*, O.S. POKROVKSY1, J.L. ROLS2, J.
VIERS1 AND L. TEN-HAGE2
GET, CNRS/UPS, 14 av Edouard Belin, 31400 Toulouse,
France (*correspondence: [email protected])
2
EcoLab, CNRS/UPS, 118 rte de Narbonne, 31062 Toulouse
cedex 9, France
1
In geochemistry, the study of the interactions between
trace metals (TM) and aquatic microorganisms is limited
essentially by the characterisation of surface’s interactions for
short exposure time and for uptake experiments for selected
monospecific groups of algae and bacteria. The originality of
our work is to combine the study of Cu and Zn isotope
fractionation with biological characterisation of phototrophic
biofilms during long incubation times in order to allow for the
integration of an ecological dimension.
Towards this goal, batch and open flux experiments
including trace metals (TM) sorption, incorporation and
extracellular release were performed on mature biofilm having
a cyanobacterial dominance. Moreover, the impact of
temporary drying on metal release from biofilm was studied.
Anothers experiments were performed in Taylor Couette
reactor to study the relation between a biofilm growth cycle
and the degree of stable isotope fractionation during metal
uptake.
Results show that in batch reactor, the pattern of metal
isotope fractionation is dramatically different between Zn and
Cu. There is an accumulation of heavy Zn isotope in the
biofilm during the first 96 hours with an average isostopic
shift close to 0,3 ± 0,1 ‰. In contrast, the copper interacting
with biofilm during 48 hrs is enriched in light isotopes (approx
0,16 ± 0,07 ‰) but later this trend is reversed bringing to
enrichment the biomass in heavy isotope. The observed
difference may be linked to (i) the different toxicity of metal
with Cu being more toxic than Zn and (ii) the difference of
physicochemical properties of metal interaction reactions:
internalization of copper is faster than that of Zn and only Cu
could undergo redox reaction within the biofilm matrix and
inside the cells.
Our results provide firm basis for establishing the link
between metal complexes structure and toxicity and the degree
of stable isotope fractionation that can be used for tracing
biological processes in natural waters.
Mineralogical Magazine
Montalto Formation:
A Middle Cambrian to basal
Ordovician sequence in Dúrico-Beirã
area (Northern Portugal)
H. COUTO
Universidade do Porto, Faculdade de Ciências, DGAOT,
Centro de Geologia, Rua do Campo Alegre 687, 4169-007
Porto, Portugal ([email protected])
Montalto Formation [1] occur in Dúrico-Beirã area
(northern Portugal) in Central-Iberian Zone. It's formed by
three lithologic associations. The Lower lithologic association
is mainly composed of grey and violet slates with
intercalations of altered volcanic acid rocks and exhalites. The
Intermediate lithologic association is composed by alternating
sequences of slate, quartzite, and subordinate wacke. The
Upper lithologic association is mainly composed of
conglomerates usually clasto-suported with minor pelite,
siltite, quartz arenite and wacke intercalations. Some
conglomerates are well calibrated dominantly bearing quartz
clasts usually elongated and orientated. Other conglomerates
occurring to the top of the sequence are polygenic, poorly
calibrated with clasts of varied nature (quartz, schist, black
quartzite) intersperse with pelitic or quarztic layers evidencing
a more superficial facies, probably continental. Dykes of
diabase are particularly frequent in this lithologic association.
This formation overlies the Terramonte Formation [1], a thick
flyschoïd sequence, showing some turbiditic characters being
equivalent to Desejosa Formation defined in Douro Group
(Lower Cambrian to Middle Cambrian) [2]. Montalto
Formation underlies a lithologic association mainly composed
of conglomerates, quartz-arenites, minor pelites and wakes
interbeded with volcanic rocks exhibiting bimodal
composition (volcanoclastic rocks of rhyolitic affinities and
basic volcanic rocks) that evidence a continental rifting [3] of
probably Tremadocian age. To the top the Armorican
quartzites occur (Floian). So, an age between Middle
Cambrian and basal Ordovician (Tremadoc) is proposed to
Montalto Formation. This contrast to a Floian age proposed by
some authors [4] when correlating Montalto Formation to
Vale de Bojas Formation and Eucísia Formation (Trás-osMontes). These last formations can be correlated to the
volcano-sedimentary sequence of probable Tremadocian age
[3].
[1] Couto, H. (1993) Phd thesis. 607pp. Faculdade de Ciências
da Universidade do Porto. [2] Sousa, B., 1984. Cuadernos
Geologia Ibérica, Madrid, 9: 9-36. [3] Couto H. & Lourenço,
A. 2008. 33rd International Geological Congress Oslo,
Norway. SES-07 Dynamics of sedimentary basins. Abstract
CD-Rom. [ 4] Sá, A. et al. 2006. Ibérica,. VII Congresso
Nacional de Geologia, Évora, 2, 621-624.
www.minersoc.org
Goldschmidt Conference Abstracts
Late Ordovician to Lower Silurian
transition in Valongo Anticline
(Northern Portugal): Evidences of an
erosional unconformity previous to
the Silurian sea level rise
H. COUTO AND A. LOURENÇO
1,2
Universidade do Porto, Faculdade de Ciências, DGAOT,
Centro de Geologia, Rua do Campo Alegre 687, 4169-007
Porto, Portugal. ([email protected])
2
Universidade do Porto, Reitoria, Centro de Geologia, Praça
Gomes Teixeira, 4099-002 Porto, Portugal.
([email protected])
1
This work discusses the transition of Ordovician to
Silurian in Valongo Anticline. This structure is an antiform
related with the Variscan orogeny, located in the Centro
Iberian Zone (Northern Portugal). The Sobrido Formation
representing the Hirnantian glacial deposits was recently
revised [1] evidencing the presence of ice-contact deposits.
The transition between Upper Ordovician and Lower
Silurian strata is variable. Transitional sections locally record
a ferruginous level and black basal quartzites. These quartzites
seems equivalent to Vale da Ursa Formation [2] of Central
Portugal (Dornes). They are followed by black-shales or dark
grey schist turning to light grey and purple with pyrophillite
and bearing Middle to Upper Llandovery graptolites [3] with
intercalations of centimetric cherty or quartzitic layers. The
presence of a ferruginous level and the fact that sometimes
quartzites are lenticular or absent evidences a minimum
glacio-eustatic sea-level. The quartzites are interpreted to
record scour, a lag, and the development of an erosional
unconformity before the Silurian sea level rise. This is in
agreement with what has been advocated by other authors [4]
that consider the sea levels reached a minimum during the
glaciation near the Ordovician-Silurian boundary before a
further significant rise took place during the Llandovery.
Black shales were controlled by the early Silurian palaeorelief
as suggested for the Lower Silurian “hot shales” in North
Africa and Arabia [5]. This model can explain why often in
Valongo Anticline, the Lower Silurian black-shales or dark
grey schist occur in the middle of Hirnantian diamictites.
Psychrophilic methanogens:
A possible solution to more
cost-effective anaerobic wastewater
treatment
JILLIAN M. COUTO, GAVIN COLLINS AND
WILLIAM T. SLOAN
School of Engineering, University of Glasgow, Glasgow UK,
G12 8QQ
Wastewater treatment facilities are a rich source of
methane gas, an effective renewable energy source. Methane
is produced anaerobically by mesophilic or thermophilic
microbial communities and thus currently requires a net input
of energy to heat waste treatment facilities, reducing the costeffectiveness of this process. Our aim is to investigate the
potential of psychrophilic microbes to produce methane, hence
reducing the need for this net input of energy. To do this we
have designed a functional screen of metagenomes harvested
from cold temperature environments, specifically arctic soils
and cold-adapted agricultural waste sludge, which will be
scanned for novel functional candidate genes. This screen
entails scanning thousands of genes for their ability to be
activated in an anaerobic and cold environment when exposed
to intermediary metabolites produced during methanogenesis.
Similar to a previous design (Uchiyama et al, 2005) [1], genes
within our metagenomic library, housed in e-coli, will produce
a fluorescence signal when activated by these metabolites.
This is detected in a high throughput manner using
fluorescence activated cell sorting technology. Once isolated,
these candidates will then be further characterized and tested
for use within a bioreactor system, with the ultimate goal of
producing methane at cold temperatures.
[1] Uchiyama, Abe, Ikemura & Watanabe (2005), Nature
Biotechnology 23, 88-93.
[1] Couto & Lourenço (2011), Cuadernos del Museo
Geominero (in press). [2] Cooper (1980), Phd thesis, Sheffield
University, England. [3] Romariz (1962), Revista Faculdade
Ciências de Lisboa, 2ªSér. C,10 (2) 115-312.[ 4] Servais et al.
(2009) GSA Today 19 (4) 4-10. [5] Lünning et al. (2000),
Earth Science Reviews 49, 121–200.
Mineralogical Magazine
701
www.minersoc.org
702
Goldschmidt Conference Abstracts
Geochemical behavior of
(thio)arsenates with Fe-minerals
Metatranscriptomics of the green
sulfur bacteria in a meromictic Swiss
lake (Lago di Cadagno)
R.M. COUTURE1,*, D. WALLSCHLÄGER2 , K. MITCHELL1
1
AND P. VAN CAPPELLEN
Earth and Environmental Sciences, University of Waterloo,
Waterloo, Canada
(*correspondence: [email protected])
2
Environmental and Resources Studies, Trent University,
Peterborough, Canada
R.P. COX1,2*, K. HABICHT1,3 , M. MILLER2,
N. STORELLI4,5, M. TONOLLA4,5 AND N.-U. FRIGAARD6
1
Under microbially-mediated sulfate (SO4) reducing
conditions, the mobility of arsenic (As) in iron (Fe) rich
sediments is influenced by the transformations of Fe minerals
and changes in aqueous As speciation. Hence, to predict As
mobility in complex biogeochemical systems, the sorption of
aqueous As species to various Fe mineral phases should be
fully understood. However, despite the accumulating evidence
that thioarsenates dominate As speciation under a variety of
environmental conditions, their sorption behaviour in
sediments is poorly known. We used batch experiments to
measure sorption of six individual As species in suspensions
of 2-lines ferrihydrite (2L-Fh), hematite, goethite,
mackinawite (FeSm(s)) and pyrite. The table below shows the
results for FeSm(s) and 2L-Fh. As can be seen, there are marked
differences in the partition coefficients of the different soluble
As species.
FeSm(s)
2L-Fh
Arsenate
5
1600
Arsenite
3
50
Mono-thioarsenate
0.1
12
Di-thioarsenate
310
70
Tri-thioarsenate
0.2
150
Tetra-thioarsenate
1.5
120
Table: Partition coefficients (Kd; L g-1) for As sorption to
selected Fe-minerals at pH 7 and ionic strength = 0.05M.
We also used flow-through reactors (FTRs) to look at the
formation and sequestration of thioarsenates in Fe-rich and Fepoor lake sediments run under SO4 reducing conditions. The
FTRs where supplied with either soluble arsenate or soluble
arsenite. We monitored SO4, total sulfide, zero-valent sulfur,
Fe as well as pH and Eh in the outflow of the FTRs. The
results indicate that arsenate is first reduced to arsenite, which
is then sulfidized to thioarsenates. Thioarsenates only
dominated As speciation in the FTR outflow of the Fe-rich
sediments. In addition, As was released as mono-thioarsenate,
in line with the observation that mono-thioarsenate is the least
strongly bound to Fe-minerals (see Table). These preliminary
observations are currently being used to improve existing
reactive-transport models for the fate of As under sulfate
reducing conditions.
Mineralogical Magazine
NordCEE, 2Dept. Biochem. Mol. Biol., 3Inst. Biol., Univ. of
Southern Denmark, 5230 Odense M, Denmark
(*correspondance: [email protected])
4
Dept. Plant Biol., Univ. Geneva, Switzerland
5
Inst. Microbiol., Canton Ticino, Bellinzona, Switzerland
6
Dept. Biol. Univ. Copenhagen, 3000 Helsingør, Denmark
1
Lake Cadagno in the Swiss Alps is a potential modern
analog of the early ocean. The lake is permanently stratified
with anoxic water containing sulfate (1.5 - 2.0 mM) and
sulfide below the chemocline. The sulfidic water column
contains high concentrations of phototrophic sulfur bacteria
(peak concentrations more than 250 µg/L BChl e). We have
previously shown that the bacterial community in this layer is
dominated by the green sulfur bacterium Chlorobium
clathratiforme (up to 70% of recovered bacterial 16S rRNA
gene sequences in a clone library [1]. Several lines of
molecular sequence evidence suggest that this population is
clonal and has replaced the previously dominant purple sulfur
bacteria over the last decade [1]. This feature makes the lake a
highly suitable site for metatranscriptomic studies of natural
populations.
Samples were collected at the top of the chemocline
during the day (1) and at night (2) and at a depth where light
intensity precludes active photosynthesis (3). The mRNA was
converted to cDNA and subjected to high-throughput
sequencing. As expected from previous results [1,2] a high
proportion of the sequences could be matched to the genome
of Chlorobium clathratiforme BU-1 which was isolated from a
lake in Southern Germany. There were relatively small
differences in the normalised transcript levels between the 3
samples. The highest transcript levels were observed for the
major protein of the light-harvesting chlorosomes, csmA, and
the gas vesicle protein gvpA.
[1] Gregersen et al. (2009) FEMS Microbiol. Ecol. 70, 30-41.
[2] Habicht et al (2011) Environ. Microbiol. 13, 203-21
www.minersoc.org
Goldschmidt Conference Abstracts
Molecular modelling of carbon
dioxide adsorption in zeolites
J.C. CRABTREE*1, S.C. PARKER2 AND J.A. PURTON3
Doctoral Training Centre in Sustainable Chemical
Technologies, University of Bath, BA2 7AY
(*correspondence: [email protected])
2
Department of Chemistry, University of Bath, BA2 7AY
3
Daresbury Laboratory, Daresbury, Warrington, WA4 4AD
1
There is growing concern about the dangers of climate
change. The majority opinion is that a major cause is the
emission of greenhouse gases such as carbon dioxide (CO2).
Adsorption and separation of CO2 is therefore a key area of
research. Silicate materials are a promising class of material
for the adsorption of CO2 [1][2]. Natural and synthetic zeolites
have been chosen as the initial focus of this computational
study. They present a good model system as they are
microporous and there is experimental data for comparison
with simulations.
The computational methods use interatomic potentials to
describe the interactions between atoms. Energy minimisation
is used to find the most stable configurations of the zeolites.
Molecular dynamics is used to study the diffusion of CO2 in
the zeolites while Grand Canonical Monte Carlo (GCMC)
simulations are used to generate adsorption isotherms. Zeolites
have been modelled in the siliceous form and as
aluminosilicates with counter-ions. The main counter-ion that
has been considered is Na+, but the models are being extended
to cope with others including K+, Li+ and Ca+.
Figure 1: adsorption isotherm of CO2 in siliceous faujasite,
comparing simulations to experimental data [3]
The results gained in this work so far correlate well with
experimental data and the work is currently being extended to
cover a wide range of other structures and materials to find a
good selective adsorbent for CO2.
[1] Choi et al. (2009) ChemSusChem 2 796-854. [2] Wang et
al. (2011) Energy Environ. Sci 4 42-55. [3] Maurin et al.
(2005) J. Phys. Chem. B 109 16084-16091
Mineralogical Magazine
703
Fe and C isotopes in BIF carbonates:
Evidence for authigenic formation
and microbial Fe respiration
P.R. CRADDOCK AND N. DAUPHAS
Origins Laboratory, Dept of the Geophysical Sciences, The
University of Chicago ([email protected])
We report here iron ((56Fe, vs. IRMM-014 [1]) and carbon
isotopic ((13C, vs. V-PDB) compositions of Fe-rich and Fepoor carbonates in two Banded Iron-Formatios (BIF): the ~2.5
Ga Hamersley Basin, Australia and ~3.8 Ga Isua Supracrustal
Belt (ISB), Greenland [2]. In the Hamersley Basin, Fe-rich
carbonates (in the iron-formation) have (56Fe ranging widely
from -1.0 to +1.2 ‰ (mean ~ 0 ‰), different from that of Fepoor carbonates (platform dolomites) that have (56Fe lighter
than -0.5 ‰. The $13C of the same Fe-rich carbonates (-8 to
-16 ‰) are also distinct to those of Fe-poor carbonates (~ 0
‰) [3]. The Fe and C isotope compositions are inconsistent
with formation of Fe-rich carbonate in the iron-formation in
isotope equilibrium with seawater, and instead reflect an
authigenic origin via oxidation of organic carbon coupled to
near-complete reduction of ferric precursors (e.g., ferrihydrite)
in marine sediments [2,4]:
2Fe2O3·3H2O + CH2O + 7H+ & 4Fe2+ + HCO3– + 10H2O.
Organic carbon oxidation and ferric Fe reduction likely
occurred rapidly following primary deposition at the seafloor,
but the Fe and C isotope compositions of Fe-rich carbonates
indicate that chemical exchange between pore waters and
seawater was far from complete. Most likely, the reaction was
mediated by heterotrophic microbes via dissimilatory Fe
reduction; thus the Fe and C isotope data record evidence for
evolution of microbial Fe respitation by ~2.5 Ga. Further, the
authigenic formation of Fe-rich carbonate in the ironformation implies no constraint on the pCO2 of the overlying
Archean ocean and atmosphere as suggested by [5; also see 6].
Coupled Fe and C isotopic signatures of Fe-rich metacarbonates from the ISB are similar to those of known
chemical sedimentary origin from Hamersley Basin [2,7,8].
By analogy, Fe-rich metacarbonates appear to have formed as
chemical sediments and preserve isotope evidence that is
consistent with the evolution of Fe catabolims by 3.8 Ga.
[1] Dauphas N. et al. (2009) Chem. Geol. 267, 175-184. [2]
Craddock P.R. & Dauphas N. (2011) EPSL, 303, 121-132. [3]
Becker R.H. & Clayton R.N. (1972) GCA, 36, 577-595. [4]
Heimann A. et al. (2010) EPSL, 294, 8-18. [5] Rosing, M.T. et
al. (2010) Nature, 464, 744-747. [6] Dauphas N. & Kasting J.
(2011) Nature, in press. [7] Dauphas N. et al. (2004) Science,
306, 2077-2080. [8] Dauphas N. et al. (2007) GCA, 71, 47454770.
www.minersoc.org
704
Goldschmidt Conference Abstracts
Electrolyte adsorption to goethitewater interfaces
Deglacial NW Atlantic ventilation
from paired deep-water coral
radiocarbon and Nd isotopes
LOUISE J. CRISCENTI AND DAVID HART
KIRSTY C. CROCKET1*, TINA VAN DE FLIERDT1,
LAURA F. ROBINSON2AND JESS F. ADKINS3
Sandia National Laboratories, Albuquerque, NM 87185, USA
(*correspondence: [email protected])
Adsorption onto goethite surfaces is a critical process
influencing trace metal migration in the environment. This
study investigates interfacial water structure and the
adsorption of electrolyte anions and cations on different
goethite surfaces to develop a better appreciation of the local
environments that favour trace metal adsorption. The impact
of different electrolytes (e.g., NaCl, Na2SO4, Na2SeO3) over a
range of concentrations on water structure and surface loading
will be presented.
Two goethite surfaces, the (100) and (101) surfaces as
defined in the Pnma space group are under investigation. The
(100) surface has three types of surface sites (5-fold Fe,
Fe2OIH, Fe3OII) and the (101) surface has four types of sites
(Fe1OIIH, Fe2OIIH, Fe3OII, and Fe3OIH). To date, molecular
dynamics (MD) simulations have been performed to
investigate the impact of 1M – 5M NaCl concentrations on
interfacial water structure and surface loading. Each surface
slab contains 192 Fe atoms and is protonated to create a
neutral slab. The density of the bulk solution is maintaned at
1.0 g/L regardless of salt concentration. A Leonard-Jones wall
is imposed at both the top and bottom of the simulation cell.
A natural surface of water is allowed to form at the top of the
cell through an NPT simulation. Then, a vacuum gap three
times the cell height is added to prevent interactions between
periodic cells in the Z direction. Production runs were
performed using the NVT ensemble at 298K for10 ns.
Water layers at the (100) surface exhibit more structure
and more hydrogen bonding with surface hydroxyl groups
than at the (101) surface. Na+ adsorbs as inner-sphere complex
to both surfaces; Cl- adsorbs as an outer-sphere complex.
From atomic density profiles, the introduction of 5M NaCl
does not change the overall interfacial water structure,
reinforcing previous MD studies that also suggest that the
electric double layer is dominantly formed by interfacial water
structure rather than ions at the surface.
This research is supported by the U.S. Department of
Energy, Office of Basic Energy Sciences, Division of
Chemical Sciences, Geosciences, and Biosciences. Sandia is a
multiprogram laboratory operated by Sandia Corporation, a
Lockheed Martin Company, for the United States Department
of Energy’s National Nuclear Security Administration under
contract DE-AC04-94AL85000.
Mineralogical Magazine
Earth Science and Engineering, Imperial College London,
London SW7 2AZ, UK. (*[email protected]).
2
Department of Earth Sciences, University of Bristol, Bristol
BS8 1RJ, UK.
3
GPS, Californian Institute of Technology, 1200 E. California
Blvd., Pasadena, CA 91125, USA
1
Sequestration of carbon in the deep ocean during glacials
and its subsequent release during deglaciation undoubtedly
play a role in glacial/interglacial variation of atmospheric CO2,
although concrete evidence of the ocean’s role has yet to be
established. One route of investigation is to determine ocean
ventilation rates. To do so requires combining dynamic tracer
data, such as radiocarbon, with a conservative tracer to
identify the water masses involved and their mixing ratios.
We describe the use of deep sea corals as an archive
material providing same-sample U/Th ages, radiocarbon data
and conservative water mass tracer data in the form of Nd
isotope compositions. The majority of corals in this study are
deglacial in age and span a water depth of 1000 to 2600 m in
the NW Atlantic, where changes in the water column structure
were pronounced across the last glacial/interglacial cycle [1].
Additional coral samples are located in the NE Atlantic and
the northernmost parts of the North Atlantic to provide a
broader picture of change.
This study builds on existing coral work, which has
identified radiocarbon age reversals within single specimens
[2] and rapid changes in radiocarbon content of the NW
Atlantic water column [1]. By pairing the Nd isotope data to
the radiocarbon data, we are able to identify the water masses
present in the NW Atlantic during the deglaciation, the extent
of mixing between these, and ultimately to translate the
radiocarbon data into ocean ventilation rates.
[1] L.F. Robinson, et al. (2005), Science 310, 1469-1473.
[2] J.F. Adkins, et al. (1998), Science 280, 725-728.
www.minersoc.org
Goldschmidt Conference Abstracts
Sinking Titanic ( TiIV) – Insights into
the speciation and distribution of
Titanium in the Atlantic Ocean
Gas Phase Low Volatility Organic
Compounds (LVOCs):
Measurements from chambers,
planes and automobiles
P. CROOT1, A. DAMMSHÄUSER2AND M. HELLER3
Plymouth Marine Laboratory, Plymouth, United Kingdom
([email protected])
2
IFM-Geomar, Kiel, Germany
([email protected])
3
IFM-Geomar, Kiel, Germany ([email protected])
E.S. CROSS1*, K.E. DAUMIT1, J.F. HUNTER1,
A.J. CARRASQUILLO1, A.G. SAPPOK1, V. WONG1
S. HERNDON2, J.T. JAYNE2, D.R. WORSNOP2 AND
J.H. KROLL1
1
Titanium is a major component of the continental crust but
is found in very low concentrations (< 300 pM) in seawater
due to the strong hydrolysis of titanic (TiIV) and/or titanyl
(TiO2+) ions resulting in the formation of the poorly soluble
TiO2 (or TiO(OH)2). The reduced form of Ti, titanous (TiIII),
is a strong reducing agent and is subsquently rapidly
reoxidized to TiIV under all but the strongest reducing
conditions.
There is no known biological enzyme that utilizes
titanium and no organism has been found to require it for
growth. However in recent years, research has been focused
on Ti-complexes as potential anti-cancer drugs and in the
utilization of TiIV to form nano-structures by the same
enzymes that diatoms use to construct their silicate shells.
Other recent developments include the common useage of Ti
as a bio-inert substrate in the body and the increasing use of
nanoparticle TiO2 in a range of products. This increased
exposure to Ti in our daily lives has new investigations into
the biochemistry of Ti and revealed the potential for Ti
competition for strong Fe(III) binding sites in organisms (e.g.
transferrin).
To investigate the biogeochemistry of Ti in the ocean we
recently developed a new sea-going voltammetric technique
capable of rapidly measuring pM dissolved Ti, and we have
applied this to work on a number of cruises in the Atlantic,
including the preliminary German GEOTRACES cruise of
2005 and the IPY GEOTRACES Zero-Drake cruise in the
Atlantic sector of the Southern Ocean. In this presentation we
will outline our new findings on the speciation of dissolved Ti
in the ocean, focusing on the evidence, or lack of it, for the
existence of titanium-organic complexes in seawater. Finally
we will show the distribution of dissolved Ti throughout the
water column in the Atlantic ocean and comment on its
potential for use as a tracer of dust input similar to Al and Fe.
Mineralogical Magazine
705
Massachusetts Institute of Technology, Cambridge, MA
02139 USA
2
Aerodyne Research Inc., Billerica, MA 01822 USA
1
Gas phase low volatilty organic compounds (LVOCs)
comprise an atmospherically important, largely unmeasured
class of organic species in the atmosphere. LVOCs consist of
intermediate volatility organic compounds (IVOCs; i.e. C13C20 n-alkanes) and semivolatile organic compunds (SVOCs;
i.e. C21-C32 n-alkanes). Atmospheric oxidation of gas phase
LVOCs results in the formation of secondary organic aerosol
(SOA) which in turn has direct implications for climate and
human health. The rates and the chemical properties of LVOC
emissions and oxidation products (in the gas phase and
particle phase) are poorly characterized and not accurately
parameterized in atmospheric chemistry models.
This paper will provide an overview of experimental
results obtained with a novel technique called the Total Gas
Phase Organics (TGO) instrument that provides a volatilityresolved, quantitative measure of gas phase LVOCs (and
LVOC oxidation products) in the atmosphere. Experimental
results from instrument characterization studies, chamber
oxidation studies, and LVOC emissions characterization
studies (including a medium duty diesel engine and the NASA
DC-8 aircraft engine) will be presented. The capability of the
TGO instrument for tracking total gas phase carbon during a
chamber oxidation experiment will be discussed.
www.minersoc.org
Goldschmidt Conference Abstracts
706
New juvenile glass chemistry from
Colli Albani, Italy and its use in
understanding petrogenesis
JO CROSS1*, VICTORIA SMITH2, GUIDO GIORDANO3,
JULIE ROBERGE4, EMMA TOMLINSON1AND
MARTIN MENZIES1
Department of Earth Sciences, Royal Holloway University of
London, Egham Hill, Egham, Surrey, TW20 0EX
(*[email protected])
2
RLAHA, University of Oxford, Dyson Perrins building,
South Parks Road, Oxford OX1 3QY, UK
3
Dipartimento di Scienze Geologiche, Università di Roma
TRE - L.go S. Murialdo 1, 00146 Roma, Italy
4
Departamento de Geoquímica, Instituto de Geología,
Universidad Nacional Autónoma de México, Ciudad
Universitaria, Coyoacán D.F. 04510, Mexico
1
Colli Albani is a quiescent caldera complex located within
the Roman Comagmatic Province, Italy. The recent Via dei
Laghi phreatomagmatic eruptions led to the formation of
nested maars. The largest is Lago Albano (ca 70-20ka) which
has erupted at least seven times. The highly explosive nature
of the eruptions from Colli Albani and contrasting alkali-rich,
silica under-saturated magma compositions has resulted in
several contrasting petrogenetic models [1].
Results are presented from a petrological and geochemical
study of the Lago Albano deposits. Juvenile clasts in the
deposits display evidence for mingling of different melt
fractions. The juvenile (magmatic) fragments from explosive
(base surge and fall deposits) and effusive (lava flows)
episodes provide an opportunity to constrain the temporal
magmatic and volatile history of the system. New WDSEPMA and LA-ICPMS data for interstitial glass in magmatic
cumulates (pre-eruptive), and melt within juvenile clasts (syneruptive) reveal extreme sub-volcanic fractionation generating
distinct magma compositions (K-rich foidites).
Oxidative weathering fractionates
chromium isotopes
S.A. CROWE1*, L.N. DØSSING2, L.C.W. MACLEAN3,
R. FREI2, D.A. FOWLE,4, A. MUCCI5 AND D.E. CANFIELD1
Institute of Biology, Univ. of Southern Denmark and Nordic
Center for Earth Evolution, Odense, Denmark
([email protected])
2
Dept. of Geography and Geology, Univ. of Copenhagen and
Nordic Center for Earth Evolution Copenhagen, Denmark
3
Canadian Light Source, Saskatoon, Canada
4
Dept. of Geology, Univ. of Kansas, Lawrence, USA
5
Dept. of Earth and Planetary Sciences, McGill Univ.,
Montreal, Canada
1
Cr isotopes hold great promise for use as a paleoredox
proxy, but the processes that induce Cr isotope fractionation
remain speculative. The reduction of Cr(VI) favours the light
Cr isotope, causing residual Cr(VI) to become progressively
heavier [1], but we do not know if fractionation accompanies
the oxidation of Cr(III) to Cr(VI). We present Cr isotope ratio
measurements of a lateritic soil profile from Indonesia. Our
measurements reveal that the Cr isotopic composition of the
soil becomes progressively lighter with increased weathering
up the profile. The uppermost unit, the topsoil, possesses the
lightest composition, #53Cr = -1.19 ! 0.25 " (#53Cr = 1000 x
[(53Cr/52Cr)sample/(53Cr/52Cr)SRM979)-1]), whereas the unaltered
peridotite bedrock has Cr isotope ratios consistent with
mantle-derived igneous rocks [2].
Our measurements
demonstrate the preferential retention of light Cr in the soil
and the release of heavy Cr(VI) to runoff, supporting the
hypothesis that the marine Cr isotope record tracks the
oxygenation of the atmosphere through geological time [3].
[1] Ellis, Johnson, & Bullen (2002) Science 295, 2060-2062.
[2] Schoenberg et al. (2008) Chem. Geol. 249, 294-306. [3]
Frei et al. (2009) Nature 461, 250-254.
[1] Conticelli et al. (2010), IAVCEI Sp Pub
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Magmatic processes leading to
explosive mafic eruptions of Volcán
de Colima, Mexico
JULIA CRUMMY1*, IVAN SAVOV1, DAN MORGAN1,
CARLOS NAVARRO2, MARJORIE WILSON1AND
SUE LOUGHLIN3
University of Leeds, Leeds, LS2 9JT, UK
(*correspondence: [email protected],
[email protected], [email protected],
[email protected])
2
Colima Volcano Observatory, University of Colima, Colima,
Mexico ([email protected])
3
British Geological Survey, Murchison House, Edinburgh,
EH3 3LA, UK ([email protected])
1
We present new geochemical and petrological data for the
Holocene tephra deposits of Volcán de Colima. Historically,
the volcano is characterised by mostly effusive andesitic lava
flows and frequent Vulcanian-style explosions (up to 11 times
per day in 2010), producing steam and ash clouds reaching
heights of several km. Explosive basaltic-andesitic Plinian
eruptions at Colima have occurred throughout the Holocene.
The last such event was the 1913 eruption which produced an
ash column 23km in height, and pyroclastic flows which
travelled 15km from the vent. Ash was reported in the town
of Saltillo 725km away. The 1913 eruption lava and ash
samples contain magmatic water contents of up to 6.3 wt.%.
Deposits representing highly-explosive activity at Volcán
de Colima reveal a tantalising story of magma evolution over
a 30,000 year period [1]. We report results concerning the
4,400 and 4,700 yrs B.P. eruptions, which represent the felsic
and mafic end-member magma, and show that Plinian-style
explosions can occur at Colima over a range of compositions
from basaltic-andesite to high-silica andesite, all with a
common, high H2O content of over 4.3 wt.% H2O.
SEM, EPMA and CSD analyses support the bulk rock
dataset and reveal a complex crystallisation history of the
4,400 and 4,700 yrs B.P. magmas. However, Sr isotope
analyses indicate a well-established feeder system with little
change in 87/86Sr ratios (0.703459 - 0.703735, n=61) over
>12,000 years.
At Volcán de Colima, high-MgO magmas (5.61 wt.%) are
H2O rich, implying little mixing and/or very fast ascent rates
from source to surface.
U and Sr isotopic variations at a deep
underground laboratory,
Homestake Mine, SD
M.F. CRUZ1*, K. MAHER1, N. OLSEN1, T. JONES2,
M. CONRAD3AND E. SONNENTHAL3
GES Dept., Stanford University, Stanford, CA 94305, USA
(*correspondence: [email protected],
[email protected])
2
South Dakota School of Mines, Rapid City, SD 57701, USA
([email protected])
3
Lawrence Berkeley National Lab, Berkeley, CA 94720, USA
([email protected], [email protected])
1
The U and Sr isotopic composition of groundwater in
fracture-dominated flow systems can potentially provide a
useful means of quantifying fluid flow, reaction rates and/or
the extent of exchange with the bulk matrix.
The Deep
Underground Science & Engineering Laboratory (DUSEL) at
the former Homestake gold mine in South Dakota provides a
unique opportunity to assess the behavior of U and Sr isotopes
in a fracture-dominated environment.
The folded and
fractured metapelites are low-permeability with flow localized
in fractures and shear zones. Samples from depths up to 5000
ft below the surface were analyzed for major and trace
elements, #18O, #D, 87Sr/86Sr and (234U/238U),.
The (234U/238U) values of waters at the site is 2.99 at the
surface, then increases to 3.24 at 800 ft depth, then decreases
gradually to 1.94 at 4,850 ft depth. We interpret the initial
increase to alpha-recoil enrichment of 234U, while the
subsequent decrease suggests that as temperature increases
with depth, mineral dissolution dominates. This is consistent
with 87Sr/86Sr values, which increase with depth from 0.71 to
0.77, approaching the bulk-rock value of 0.76 to 0.8, again
suggesting increased reactivity. By coupling Sr and U
isotopes with field and geochemical data investigations at
DUSEL can provide further insights as to the isotopic
exchange processes during fracture-dominated water-rock
interactions.
[1] Luhr et al 2010, Journal of Volcanology & Geothermal
Research, v. 197, p. 1-32
Mineralogical Magazine
707
www.minersoc.org
708
Goldschmidt Conference Abstracts
Geochemistry of the Artic Loki’s
Castle hydrothermal vent products
M.I. CRUZ1, A.S. DIAS1, J.M.R.S. RELVAS1,
C. CARVALHO1, RITA FONSECA2, R.B.-PEDERSEN3 AND
F.J.A.S. BARRIGA1
Creminer/LA-ISR, Geology Department, University of
Lisbon, Portugal (corresponding author: [email protected])
2
Creminer/LA-ISR, Geosciences Dep., Univ. Évora, Portugal
3
Centre for Geobiology, Department of Earth Science,
University of Bergen, Norway !!
1
Loki’s Castle is the northernmost hydrothermal vent field
known to date in the Arctic Ocean [1]. It is located in the
junction between the Monhs and Knipovich Ridge, an ultraslow spreading center at a rate of 17mm/year [2]. ROVcollected samples of chimney fragments and their surrounding
deposits revealed to be mostly composed of sphalerite,
chalcopyrite, pyrite and anhydrite, their maximum metal
contents for Fe 31wt%, for Zn 5.4wt% and for Cu >1wt%.
The surrounding sediments contain a significant hydrothermal
component, denounced by high metal contents that average
4.6 wt% Fe, 100 ppm Zn and 33 ppm Cu. Sediments from the
same area collected at depth by gravity cores show equally
high average metal contents; although the Cu and Zn
enrichment may be more prominent in particular layers
reaching 446 ppm Zn and 128 ppm Cu. The REE sediment
patterns mimic those of the North American Shale Composite
[3]. Major and trace element geochemistry of the less altered
volcanic rock fragments collected near the vent field allows
their classification as tholeiitic basalts.
[1] Pedersen, R.B., et al., (2010) Discovery of a black smoker
vent field and vent fauna at the Arctic Mid-Ocean Ridge. Nat
Commun,. 1(8): p. 126. [2] Peive, A.A. and N.P. Chamov,
(2008) Basic tectonic features of the Knipovich Ridge (North
Atlantic) and its neotectonic evolution Geotectonics,. 42
(Number 1): p. 7. [3] Gromet, L.P., et al., (1984) The "North
American shale composite": Its compilation, major and trace
element characteristics. Geochimica et Cosmochimica Acta,
48: p. 2469-2482.
Metamorphic reaction rates from
diffusion of Nb in rutile
ALICIA M. CRUZ-URIBE1, MAUREEN D. FEINEMAN1 AND
THOMAS ZACK2
The Pennsylvania State University, State College, PA 16802,
USA ([email protected], [email protected])
2
Institut für Geowissenschaften, Universität Mainz, Becher
Weg 21, 55128 Mainz, Germany ([email protected])
1
Determining the timescales over which metamorphic
reactions occur has long been an important and difficult
question to answer. Here we examine rutile replacement by
titanite in a migmatized garnet amphibolite from Catalina
Island, CA, and compare the data to results from an
amphibolitized eclogite from Tromsø, Norway. We estimate
the timescales and rates of the rutile-to-titanite reaction by
fitting models of Nb back-diffusion during titanite
replacement to measured Nb profiles in rutile.
Trace element concentrations in rutile and titanite were
determined by LA-ICP-MS for grains from Catalina. Niobium
profiles across two rutile grains show clear evidence for Nb
back-diffusion into rutile during titanite growth at the grain
boundary (from 2280 to 3050 ppm over 350 µm). The same
feature was reported and modeled by Lucassen et al. [1] for
Nb and Zr in a 7 mm rutile from Tromsø. Zr-in-titanite
thermometry suggests 740-770°C for Catalina and 650-730°C
for Tromsø. New experimentally-determined diffusion
coefficients for Nb in rutile (R. Dohmen, pers. comm.) were
used to model Nb diffusion in the Catalina rutile, and to revisit
the Tromsø sample in light of the new diffusion data.
A simple 1-D moving interface diffusion model yields
reaction front velocities, which were converted to rates using
the distance the boundary had moved relative to the prereaction rutile surface. Reaction rates of 0.2–2.0 x 10-6 a-1 were
determined for Catalina, and 0.03–4.99 x 10-8 a-1 for Tromsø.
Reaction rates were then normalized to the surface area of the
rate-limiting mineral per unit of rock (Rnet, g/cm2/a).
Normalized reaction rates for Catalina are 0.18–1.42 x 10-5
g/cm2/a and for Tromsø are 0.04–5.82 x 10-7 g/cm2/a, which
suggests 2-3 orders of magnitude difference in Rnet over
~120°C change in temperature for the rutile-titanite reaction.
Reaction rates for the Tromso sample are consistent with those
previously determined for regional metamorphism, whereas
the Catalina reaction rates fall between those reported for
regional and contact metamorphic settings [2].
This
observation is consistent with the presence of free fluid or
melt during subduction-related metamorphism.
[1] Lucassen et al. (2010) Cont. Min. Pet. 160, 279-295. [2]
Baxter (2003) Geol. Soc. Lon. Spec. Pub. 220, 183-202.
Mineralogical Magazine
www.minersoc.org
Goldschmidt Conference Abstracts
Geological characteristics and genesis
discovery of native copper in East
Tian Mountain, Xinjiang, P.R. China
CUI BIN, HE ZHIJUN AND ZHAO LEI
China University of Geosciences , Beijing, 100083
[email protected], [email protected])
The Dongtianshan copper is a type of mineralization belt
newly found by work in recent years. The copper from
Shilipo, Dongtianshan is found in maroon basaltic tuff.
Through analysis of the geochemical characteristics show the
formation of Dongtianshan copper relates to the mineralization
of the mantle plumes. The main elements of two mineral occurrences are of the
similar content characteristics. The K2O and Na2O content in
Shilipo is apparently lower than that of Heilongfeng, but is
similar to that of Bingdao volcanic rocks. Compared the
copper-bearing basalt with Bingdao basalt, the MgO content
of Dongtianshan basalt is relatively low, in the range of
3.06%-3.61% while the MgO content of Bingdao basalt is
7.53%-12.24%. To the alkali content, the Bingdao basalt has
high Na2O, but no high K2O
The copper-bearing basalt from Dongttanshan shows the
LR/ HR of 11.29*10-6 and 11.58*10-6,a little higher than the
values of Bingdao basalt. However, the content values of the
MREE and HREE have not much difference between
Dongtianshan basalt and Bingdao basalt and show the
relatively strong comparability. The Emeishan basalt with the
LR/HR of 41.21*10-6. In the curve ofn, Emeishan basalt
presents the right-inclined shape of LREE slight
concentration. The REE partition pattern of Cu-bearing basalt
from Dongtianshan has the fairly strong comparability with
the REE partition curve of the Bingdao basalt related to
mantle plumes, reflecting the characteristics of the mantle
magma.
It is considered that the copper-bearing basalt of
Dongtianshan is from mantle sources and possesses the similar
characteristics to the mantle plumes.
[1] Kutina J. (1996). The role of mantle-rooted structural
discontinuities in concentration of meatals. Global Tectonics
and Metallogeny, 5:79-102.
Mineralogical Magazine
709
Water pollution treatment of chinese
highway tunnel construction
CUI GUANGYAO1*, WANG MINGNIAN1, LU JUNFU2 ,
ZHANG WEIQING1AND WANG WEIJIA1
School of Civil Engineering, Southwest Jiaotong University,
Chengdu, 610031, China
(*correspondence: [email protected])
2
State Key Laboratory of Geohazard Prevention and
Geoenvironment Protection, Chengdu University of
Technology, Chengdu, 610059, China
1
The damage to water environment in highway tunnel
construction is mainly manifested in two aspects: the
destruction of groundwater system in the tunnel area and
wastewater pollution generated in the process of highway
tunnel construction. The steady-state of groundwater system in
the tunnel area must be destroyed in the process of highway
tunnel construction, and the highway tunnel will become the
natural channel discharging underground water. The waste
water generated in the process of highway tunnel construction
will also pollute groundwater system in the tunnel area and
damage surrounding environment.
Water pollution treatment mainly focus on the six aspects:
(1) construction and domestic garbage must be stacked
centrally; (2) the domestic sewage can be discharged only
after it is disposed; (3) the settling ponds should be build in
the tunnel area; (4) the storehouse storing grease must be
make anti-seepage treatment; (5) mechanic waste oil should be
recycle or carefully dispose; (6) the management of chemical
grout must be strengthen.
Taking the route that can develop continuously is the
inevitable choice of 21 centuries China. To the sustainable
development, the water environmental protection is of critical
importance. The highway tunnel construction and water
environmental protection go hand in hand only if we must
consider the characteristic of the highway tunnel to perfect
construction technology and take corresponding water
environmental protection countermeasure.
[1] CUI GUANG-YAO (2010) Geochimica et Cosmochimica
Acta, 74(12), Supplement 1: A199. [2] Xu WL, Zhang
JQ(2010) Geochimica et Cosmochimica Acta, 74(12),
Supplement 1: A1162. [3] Ren Y, Hu Z.Z, Yang X (2008)
Chinese Journal of Underground Space and Engineering,
4(2):365-373.
www.minersoc.org
710
Goldschmidt Conference Abstracts
Re-Os geochronology of lacustrine
organic-rich sedimentary rocks:
Systematics and implications
V.M. CUMMING1*, D. SELBY1 AND P. LILLIS2
Earth Sciences Department, Durham University, DH1 3LE,
UK (*correspondence: [email protected])
2
U.S. Geological Survey. Box 25046, MS977, Denver Federal
Center, Denver, Colorado 80225, USA
1
The Re-Os geochronometer is widely utilised to determine
precise depositional ages of marine organic-rich sedimentary
rocks (ORS). However, Re-Os systematics have not been fully
evaluated in lacustrine ORS. Lacustrine sedimentary rocks
provide an invaluable archive of continental geological
processes responding to tectonic, climatic and magmatic
influences. The lack of marine biostratigraphic constraints in
lacustrine sedimentary rocks means that correlation to global
geological phenomena requires accurate and precise
geochronological frameworks.
Here we apply the Re-Os geochronometer to the Eocene
Green River Formation (GRF), the world’s largest succession
of lacustrine ORS representing a classic model of lacustrine
deposition. We present two precise Re-Os ages of 48.5 ± 0.6
Ma and 49.2 ± 1.0 Ma from the Uinta basin that are in
excellent agreement with Ar/Ar and U/Pb dates of interbedded
tuffs within the GRF. An additional Re-Os age of 47.8 ± 9.9
Ma has a higher uncertainty attributed to a smaller spread in
187
Re/188Os ratios. This third age is from a section suggested
to have been deposited in the deepest lake setting. It possesses
higher TOC that exhibits more significant correlation with Re,
Os and trace elements than the sections which yield precise
ages. The redox sensitive trace elements are used to assess ReOs systematics in lacustrine ORS and suggest deposition from
an oxic-dysoxic water column.
In addition to geochronology, the initial 187Os/188Os (Osi)
of the GRF (~1.4-1.5) has implications for the understanding
of global ocean Os fluctuations. The Osi is similar to
continental runoff today (~1.54), suggesting that the
187
Os/188Os of continental runoff into the ocean has not
changed since the Eocene. Global ocean 187Os/188Os has
evolved from ~0.56 during the Eocene to a modern day value
of 1.06. This study suggests that global ocean Os evolution
has been driven by a decrease of unradiogenic Os flux rather
than an increase in radiogenic Os from continental runoff.
Mineralogical Magazine
Geochemical and isotopic insights
into the development of a large
caldera-forming eruption,
Atitlan Caldera, Guatemala
HEATHER S. CUNNINGHAM*
Department of Geoscience, University of Wisconsin at
Madison, 1215 W Dayton St, Madison, WI 53706 USA,
(*correspondence: [email protected])
How do large volumes of rhyolitic magma accumulate
prior to the eruption of large caldera-forming eruptions?
Rhyolitic magmas are proposed to originate either from
rhyolitic pods that are the result of rapid differentiation,
through assimilation of crustal melts, or a combination of the
two. High magma flux rates are required to sustain an
eruptable crystal-melt reservoir. These issues are evaluated at
Atitlan Caldera, Guatemala where eruption of the ~300 km3
Los Chocoyos rhyolitic ignimbrite and air fall occurred at 84
ka. Eruption of a compositionally zoned ignimbrite recorded
the presence of rhyodacite and high silica rhyolite in the
proportions of 1:4. The rhyodacite displays trace element
ratios similar to the basaltic andesite enclaves found in early
Los Chocoyos fall deposits, as well as, stratocone lavas
erupted around the caldera boundary before and after the Los
Chocoyos. In particular, the rhyodacite displays higher Sr/Y,
La/Yb and Ce/Y than the high silica rhyolites. Generation of
rhyolitic magmas by exclusive melting of old granitic crust is
inconsistent with trace element models and Sr isotopic data. Sr
isotopes for the rhyodacite and high silica rhyolite are slightly
elevated from the mafic enclave and unlike the Sr isotope
ratios for the more evolved granite. The rhyodacite can be
modeled to form via batch partial melting of the mafic
enclave, assumed to reflect the least differentiated end
member, with garnet in the residuum. The high silica rhyolite
can be modeled from 70% fractional crystallization of the
basaltic andesite and 15% assimilation of 15.2 Ma granitic
pluton exposed along the caldera boundary. Thus, partial
melting and differentiation of basaltic andesite stalled in the
crustal plumbing system with minor addition of granitic
crustal melts can account for the formation of rhyolitic
magmas at Atitlan Caldera. Thermal models project that a flux
rate of 10-2 km3/yr is required to provide enough heat to form
large volume rhyolitic eruptions. Stratocone eruption rates of
basaltic andesite at Atitlan Caldera since the Los Chocoyos are
4 x 10-3 km3/yr. Assuming a 3:1 intrusive:extrusive ratio,
current magma flux rates at Atitlan Caldera are at least 1.2 x
10-2 km/yr and able to sustain the formation of large volume
rhyolitic magmas.
www.minersoc.org
Goldschmidt Conference Abstracts
Understanding biological control and
environmental influence – unlocking
the secrets of biomineralisation
C, O and H isotope compositions of
the Wilmott and Yungul
‘carbonatites’ and the associated
fluorites in the Speewah Dome,
Kimberley Region, Australia
MAGGIE CUSACK
School of Geographical & Earth Sciences, University of
Glasgow, G12 8QQ, UK
In the natural world of biominerals elegant, functional
structures are produced from the most basic of resources.
Vertebrates have skeletons made from calcium phosphate
(apatite) while invertebrates tend to assemble mineral
structures from silica or calcium carbonate. Although the
ingredients are simple, the control of how these fundamental
building blocks are put together is very much under the
control of biological processes. Understanding this biological
control and its rôle in the formation of biominerals has
implications in a number of diverse areas. Understanding the
biomineralisation process will provide a much more accurate
interpretation of the climate information stored within marine
biominerals, e.g. brachiopods and corals. An exploration of
the biological control exerted in biomineral formation in
several phyla provides the context for the consideration of the
recording of environmental information.
Mineralogical Magazine
711
GY. CZUPPON1*, L.G. GWALANI2, A. DEMÉNY1, R.
RAMSAY2, K. ROGERS2, A. EVES2 AND CS. SZABÓ 3
Inst. for Geochemical Research, Hung. Acad. Sci., Budaorsi
ut 45, Budapest, 1112, Hungary (*correspondence:
[email protected], [email protected])
2
Speewah Metals, 22/77 Allendale Square, St Georges
Terrace, Perth, WA6000, Australia ([email protected],
[email protected], [email protected],
[email protected])
3
LRG, Dept. of Petrology and Geochemistry, Inst. of Geog.
and Earth Sci., Eötvös University, Pázmány 1/C, Budapest
1117, Hungary ([email protected])
1
The Yungul and newly discovered Wilmott ‘carbonatites’
(carbonate-cemented breccias and carbonate veins), as well as
the associated fluorite veins are located on the eastern margin
of the Kimberley Block (NW Australia). The C and O isotope
compositions of Wilmott carbonatites show a distinct negative
trend different from that observed for Yungul ‘carbonatites’,
in which the #13C and #18O values form a positive trend and
has been explained by high-temperature rock-fluid interaction
and H2O degassing. However, the observed #13C shift in
Wilmott ‘carbonatites’ requires additional processes such as
CO2 and H2O degassing. Inclusion-hosted H2O contents
(determined by vacuum crushing) range from 250 to 1300
ppm for Yungul, whereas the Wilmott ‘carbonatites’ yielded
H2O contents between 250 and 510 ppm. The H isotope
compositions determined for inclusion-hosted H2O show a
large range for Yungul ‘carbonatites’ (from -83‰ to -24‰)
with the Wilmott rocks at the lower end (from -85‰ to 60‰). #D-H2O variations in both ‘carbonatites’ indicate an
open system in which the H2O degassing took place at
relatively high temperature (>400°C). The associated fluorite
veins are characterized by high H2O contents (600-2300ppm)
with relatively high #D values (between -30‰ and -17‰)
forming a positive linear trend related to close system
evolution. The fluorite and ‘carbonatite’ trends converge to the
same isotopic composition, thus, although the fluid regimes
were likely different for fluorites and ‘carbonatites’ (i.e. open
– closed systems), the ultimate origin of the fluids could be the
same.
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