Kipf-etal Marie-Byrd-Seamounts GondwanaResearch 2014

Gondwana Research 25 (2014) 1660–1679
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Gondwana Research
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Seamounts off the West Antarctic margin: A case for non-hotspot
driven intraplate volcanism
A. Kipf a,⁎, F. Hauff a, R. Werner a, K. Gohl b, P. van den Bogaard a, K. Hoernle a, D. Maicher a, A. Klügel c
a
b
c
GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstr. 1-3, D-24148 Kiel, Germany
Alfred-Wegener-Institute for Polar and Marine Research, Postfach 120161, D-27515 Bremerhaven, Germany
University of Bremen, Postfach 330440, D-28334 Bremen, Germany
a r t i c l e
i n f o
Article history:
Received 21 December 2012
Received in revised form 28 May 2013
Accepted 11 June 2013
Available online 16 July 2013
Handling Editor: I. Safonova
Keywords:
Antarctica
Marie Byrd Seamounts
Intraplate volcanism
40
Ar/39Ar age dates
Major and trace element and Sr–Nd–Pb–Hf
Isotope geochemistry
a b s t r a c t
New radiometric age and geochemical data of volcanic rocks from the guyot-type Marie Byrd Seamounts
(MBS) and the De Gerlache Seamounts and Peter I Island (Amundsen Sea) are presented. 40Ar/39Ar ages of
the shield phase of three MBS are Early Cenozoic (65 to 56 Ma) and indicate formation well after creation
of the Pacific–Antarctic Ridge. A Pliocene age (3.0 Ma) documents a younger phase of volcanism at one
MBS and a Pleistocene age (1.8 Ma) for the submarine base of Peter I Island. Together with published data,
the new age data imply that Cenozoic intraplate magmatism occurred at distinct time intervals in spatially
confined areas of the Amundsen Sea, excluding an origin through a fixed mantle plume. Peter I Island appears
strongly influenced by an EMII type mantle component that may reflect shallow mantle recycling of a continental raft during the final breakup of Gondwana. By contrast the Sr–Nd–Pb–Hf isotopic compositions of the
MBS display a strong affinity to a HIMU-type mantle source. On a regional scale the isotopic signatures overlap with those from volcanics related to the West Antarctic Rift System, and Cretaceous intraplate volcanics in
and off New Zealand. We propose reactivation of the HIMU material, initially accreted to the base of continental lithosphere during the pre-rifting stage of Marie Byrd Land/Zealandia to explain intraplate volcanism
in the Amundsen Sea in the absence of a long-lived hotspot. We propose continental insulation flow as the
most plausible mechanism to transfer the sub-continental accreted plume material into the shallow oceanic
mantle. Crustal extension at the southern boundary of the Bellingshausen Plate from about 74 to 62 Ma may
have triggered adiabatic rise of the HIMU material from the base of Marie Byrd Land to form the MBS. The De
Gerlache Seamounts are most likely related to a preserved zone of lithospheric weakness underneath the De
Gerlache Gravity Anomaly.
© 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.
1. Introduction
Seamounts are common bathymetric features on the seafloor and
most are of volcanic origin. Although only a fraction of them have
been mapped by ship-based echo-sounding, satellite altimetry has
identified more than 13,000 seamounts taller than 1.5 km and predicts more than 100,000 seamounts higher than 1 km (e.g., Smith
and Sandwell, 1997; Wessel et al., 2010). Seamounts are important
probes of the composition and dynamics of the oceanic mantle and,
if they form parts of hotspot tracks, they can also be important recorders of past plate motions (Hofmann, 2003; Tarduno et al., 2003;
Koppers et al., 2012). They also form oases for marine life and biodiversity (e.g., Shank, 2010 for a recent review) and are significant components of hydrogeological systems focusing the exchange of heat and
fluids between the oceanic lithosphere and the oceans (e.g., Fisher et al.,
2003; Harris et al., 2004; Hutnak et al., 2008; Klügel et al., 2011). The
latter processes can lead to the formation of economically important
⁎ Corresponding author. Tel.: +49 431 600 2645.
E-mail address: akipf@geomar.de (A. Kipf).
mineral deposits (e.g., Hein et al., 2010), which are, for example, commercially mined in some accreted seamount complexes (e.g., Safonova,
2009). Seamounts are also sites of geological hazards such as tsunamis
through sector collapse during their growth stage (e.g., McMurtry et al.,
2004). Upon subduction of the ocean floor, seamounts can also serve as
prominent asperities generating earthquakes (e.g., Watts et al., 2010
for a recent review). As the subduction process can lead to crustal accretion of seamounts, they can be preserved in the accessible geological record, providing important insights from the evolution of hotspot tracks
and continental margins to biological exchange between continents
(e.g., Hoernle et al., 2002; Geldmacher et al., 2008; Portnyagin et al.,
2008; Buchs et al., 2011; Safonova and Santosh, 2012). Despite the
manifold contributions of seamounts to the dynamics of diverse earth
systems, their process of formation is still debated. Most commonly
the occurrence of isolated volcanoes distant from plate boundaries
is attributed to the upwelling of mantle plumes (e.g., Wilson, 1963;
Morgan, 1971; Courtillot et al., 2003). The absence of linear volcanic
chains and lack of spatially age progressive magmatism in many
areas has stimulated a vigorous debate on the origin of intraplate volcanism (e.g., Anderson, 2000; Foulger and Natland, 2003; see also “Great
1342-937X/$ – see front matter © 2013 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.gr.2013.06.013
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
Plume debate”, www.mantleplumes.org). Other important mechanisms of seamount formation include off-axis volcanism in the vicinity
of spreading ridges by lateral expansion of the ridge melting regime
(e.g., Batiza et al., 1990; Brandl et al., 2012 and references therein),
recycling of delaminated continental lithosphere (Hoernle et al., 2011)
and plate fracturing (e.g., Winterer and Sandwell, 1987; Natland and
Winterer, 2005). In this paper, we report for the first time an integrated
bathymetric, geochronological and geochemical data set from three
seamount provinces off West Antarctica and show that these intraplate
volcanoes are not directly linked to the activity of a mantle plume but
rather reflect remobilization and transfer of fertile mantle from beneath
West Antarctica.
The Marie Byrd Seamounts (MBS), located in the western Amundsen
Sea north of the continental shelf of Marie Byrd Land, West Antarctica
(Fig. 1), are a good example of enigmatic intraplate volcanism. They are
located on oceanic crust possibly older than 72 Ma (Heinemann et al.,
1999; Eagles et al., 2004a,b) and form an elongated cluster of volcanic edifices, that extends for more than 800 km between ~114° and ~131°W,
and ~68° and ~71°S. Based on rock fragments found in corers and
dredges carried out at a single MBS (Hubert Miller Seamount), Udintsev
et al. (2007) assumed that this structure represents a relict fragment of
continental crust which was destructed and altered by a mantle plume.
The authors, however, admit that the material recovered cannot unambiguously be interpreted as in situ rocks. Although the MBS form a vast
seamount province covering over 200,000 km2, their remote location
made sampling difficult, inhibiting elucidation of their age, magma
sources and volcanic evolution. Moreover, the relationship of the MBS
to the magmatism associated with the final break-up of Gondwana
and/or to the widespread but low volume intraplate volcanism in the
SW Pacific region (e.g., Weaver et al., 1994; Storey et al., 1999; Rocchi
et al., 2002a; Finn et al., 2005; Hoernle et al., 2006, 2010; Timm et al.,
2010) was poorly constrained.
In 2006, the R/V Polarstern cruise ANT-XXIII/4 conducted a bathymetric mapping and dredge sampling survey of five MBS and associated structures. Samples from two other volcanic complexes in the
Amundsen Sea, namely the previously studied ocean island volcano
Peter I Island (e.g., Prestvik et al., 1990; Prestvik and Duncan, 1991;
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Hart et al., 1995) and the Belgica Seamount (De Gerlache Seamounts,
Hagedorn et al., 2007) (Fig. 1), are included in our study to more fully
characterize the sources and spatial evolution of intraplate magmatism
in this region. Both Peter I Island and the De Gerlache Seamounts have
been related to hotspot activity by most previous authors.
Here, we present results of the bathymetric surveys together with
40
Ar/39Ar ages and geochemical data (major and trace element and
radiogenic Sr–Nd–Pb–Hf isotope ratios) of the recovered rocks. We
show that magmatism in the Amundsen Sea occurred at distinct
time intervals in spatially confined areas ruling out an origin through
a single stationary hotspot. Notably this volcanism appears predominantly influenced by HIMU (high time-integrated 238U/204Pb) type
mantle, requiring emplacement and upwelling of such material in the
depleted upper oceanic mantle well after the breakup of Zealandia
from Antarctica. After briefly summarizing the tectonic and magmatic
evolution affecting this part of the SW Pacific over the past 100 Ma,
we discuss our results and evaluate processes, which may cause
non-hotspot related HIMU-type intraplate volcanism in the Amundsen
Sea.
2. Tectonic and magmatic evolution of the SW-Pacific over the
past 100 Ma
Plate-kinematic reconstructions (Fig. 2) demonstrate that Marie
Byrd Land was attached to the southeastern margin of Zealandia prior
to the final breakup of Gondwana (Fig. 2a; e.g., Eagles et al., 2004a).
After the collision of the Hikurangi Plateau with the Gondwana margin
(e.g., Davy et al., 2008; Hoernle et al., 2010) and cessation of subduction
along the northern margin of Zealandia at c. 100 Ma (e.g., Weaver et al.,
1994), extensional processes set in, causing Zealandia to rift from Marie
Byrd Land (e.g., Larter et al., 2002; Eagles et al., 2004a; Boger, 2011 for a
recent review). The continental breakup initiated with the Chatham Rise
separating from the Amundsen Sea Embayment sector during the Cretaceous Normal Polarity Superchron (CNS) at about 90 Ma (Fig. 2b).
Thereafter the southwestward rift propagation jumped farther south
and separated the Campbell Plateau from Marie Byrd Land just before
chron C33 (83–79 Ma), leaving a rifted West Antarctic continental
Fig. 1. Overview map of West Antarctica and the Amundsen Sea. The three seamount/ocean island volcanic provinces of the Amundsen Sea are marked by yellow circles. Dashed red
lines indicate major tectonic lineaments (WARS — West Antarctic Rift System from Müller et al. (2007); DGGA — De Gerlache Gravity Anomaly). The map is based on the GEBCO_08
Grid (version 20091120, http://www.gebco.net).
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A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
Fig. 2. Plate-tectonic reconstruction from 100 Ma to 22 Ma, using rotation parameters by Eagles et al. (2004a). Illustrated are the collision of Hikurangi Plateau with Zealandia at
around 100 Ma, the breakup between Zealandia and West Antarctica at 90–80 Ma, the development of the Bellingshausen Plate and the subsequent volcanism along the West
Antarctic margin. Double lines mark spreading ridge plate boundaries, single solid lines mark other plate boundary types, and dashed lines in West Antarctica illustrate lineaments
of the West Antarctic Rift System (Eagles et al., 2009; Gohl et al., 2013). Abbreviations are: SNS South Island New Zealand, HIK Hikurangi Plateau, CP Campbell Plateau, CR Chatham
Rise, GSB Great South Basin, BS Bollons Seamount, BT Bounty Trough, WA West Antarctica, MBL Marie Byrd Land, AP Antarctic Peninsula, ASE Amundsen Sea Embayment, WARS
West Antarctic Rift System, PAC Pacific Plate, PHO Phoenix Plate, BP Bellingshausen Plate, MBS Marie Byrd Seamounts (red area marks volcanic activity of the shield phase),
DGS De Gerlache Seamounts, PI Peter I Island, DGGA De Gerlache Gravity Anomaly (suture of former PHO-BP ridge jump).
margin bordering the Amundsen Sea (Fig. 2c, d; Larter et al., 2002;
Eagles et al., 2004a).
During the late Cretaceous/Early Tertiary the southern Pacific region was sectioned into a minimum of three major tectonic plates
(Bradshaw, 1989; Larter et al., 2002; Eagles et al., 2004a; Wobbe et al.,
2012), the Pacific Plate, the Bellingshausen Plate, and the Phoenix or
Aluk Plate adjacent to the Antarctic Plate (Fig. 2e). While the Phoenix
Plate subducted beneath the eastern portion of the Antarctic Plate, the
other plate boundaries were divergent or transform margins. During
C27 (61 Ma) the Bellingshausen Plate ceased from being a separate
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
plate and became incorporated into the Antarctic Plate (Fig. 2f; Eagles
et al., 2004a,b; Wobbe et al., 2012). Heinemann et al. (1999) and Stock
(1997) suggest that the MBS province formed in the vicinity of the
Antarctic–Pacific–Bellingshausen triple junction. Between C27 and C25/
C24 (57–54 Ma), a substantial drop in spreading rate occurred at the
Pacific–Antarctic Ridge, and together with a gradual rotation of the
spreading direction (Müller et al., 2000), an increase in fracture zone
density is notable (Eagles et al., 2004a). At the same time, the West Antarctic Rift System (WARS) continued its crustal extension in Marie Byrd
Land and possibly into the Amundsen Sea Embayment just south of the
MBS (Gohl et al., 2013). The De Gerlache Seamounts and Peter I Island
are aligned along the so-called De Gerlache Gravity Anomaly (DGGA)
(Gohl et al., 1997a; McAdoo and Laxon, 1997; Hagedorn et al., 2007)
(Fig. 2g + h) which was initially interpreted as a fracture zone of the
earlier Phoenix–Antarctic Ridge (Hart et al., 1995). However, magnetic
seafloor spreading data imply that this is a tectonic scar caused by a
westward jump of the Pacific–Phoenix ridge at chron C27 (Larter et al.,
2002; Eagles et al., 2004a). Müller et al. (2007) suggested that this
zone of possible lithospheric weakness was reactivated by a northward
extension of a later WARS branch (Figs. 1 and 2h).
The Late Cretaceous tectonic events were accompanied by intense
volcanism in East Gondwana and Marie Byrd Land at c. 95–110 Ma
(e.g., Hart et al., 1997; Storey et al., 1999). This magmatism has been related to large-scale mantle upwelling in conjunction with extensioninduced rifting (Finn et al., 2005). Others assume an active mantle
plume in the area of the Bellingshausen–Amundsen Sea or beneath
East Gondwana (Hole and LeMasurier, 1994; Weaver et al., 1994;
Rocholl et al., 1995; Hart et al., 1995, 1997; Panter et al., 2000; Hoernle
et al., 2010; Sutherland et al., 2010), which may have caused the final
break-up of Zealandia from Antarctica (e.g., Weaver et al., 1994; Storey
et al., 1999; Hoernle et al., 2010). As the region underwent further
plate reorganization, a second phase of volcanism occurred (Rocchi
et al., 2002a,b; Nardini et al., 2009 and references therein, LeMasurier
et al., 1990). This younger magmatism (30–25 Ma until recent) is mainly
of alkaline nature and has been related to rifting and crustal extension
associated with the WARS. Based on a HIMU (high time-integrated
U/Pb) component found in many WARS volcanics, many authors suggest reactivation of old plume material embedded at the base of the
continental lithosphere (e.g., Weaver et al., 1994) others favor a metasomatic origin (e.g., Nardini et al., 2009).
3. Bathymetry and morphology of Marie Byrd Seamounts and
Peter I Island
During cruise ANT-XXIII/4, the onboard Atlas Hydrosweep DS-2
multi-beam echo-sounding system of the R/V Polarstern was used to generate maps of five MBS (summarized in Table 1; Fig. 3a) and of the submarine base of Peter I Island (Gohl, 2007). Combined with bathymetric
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data of previous cruises (RV Nathaniel B. Palmer in 1996, RV Polarstern
ANT-XI/3 in 1994, and ANT-XVIII/5a in 2001; e.g., Miller and Grobe,
1996; Feldberg, 1997), these data reveal that the MBS are characterized
by steep sides with relatively flat tops and additional small cones
on the upper flanks and/or on the platforms. The guyot-like morphology of the main edifices is attributed to seamount growth
above sea level to form ocean island volcanoes, which subsequently
eroded to sea level and then subsided to their present position. The
small cones must have formed after subsidence of the erosional platforms below wave base and therefore represent a late stage or
post-erosional phase of volcanism.
The westernmost studied seamount, Seamount 6 (informal name),
has an elongate WNW–ESE striking base (Fig. 3b). The steep-sided edifice
is topped by a flat plateau, on which several well-preserved small volcanic cones are scattered, rising up to 200 m above the plateau. Seamount 9
(informal name) is located about 45 km east of Seamount 6. One track
was surveyed across Seamount 9 (not shown in Fig. 3), which revealed
an oval shaped guyot and a c. 10 km long WNW–ESE-trending ridge emanating from its western base. This ridge is composed of several aligned
small volcanic cones and interpreted as volcanic rift zone. Haxby Seamount (named by the ANT-XIII/4 cruise participants) (Fig. 3c), which
has been mapped previously on RV Nathaniel B. Palmer Cruise in 1996
(Feldberg, 1997), has a slightly curvilinear volcanic rift system with numerous cones on its top emanating from the eastern flank of the guyot
and extending N 30 km to the east. Two less pronounced, c. 12–15 km
long chains of cones and ridges emanating from the western flank may
be the western continuation of the volcanic rift. Hubert Miller Seamount
(Fig. 3d) is located ~75 km ESE of Haxby Seamount. This seamount is
the largest MBS with frequent small cones and ridges scattered along
its flanks but infrequent on the plateau. Several up to 8 km long volcanic
rift zones extend from the base of Hubert Miller Seamount. The easternmost mapped seamount, Seamount C (informal name; Fig. 3e), is
the smallest of the studied volcanoes. Its guyot-shaped edifice has a
crudely circular base and a plateau of ~7 km diameter. Volcanic rifts extend from the base in northern and southern directions and NNE–SSW
trending, curvilinear graben and ridge structures are adjacent to its
eastern flank. The existence of further, most likely sediment covered,
volcanic cones and ridge-like basement structures between the main
MBS cluster and Marie Byrd Land are predicted from satellite gravity
data (Smith and Sandwell, 1997) and observed in seismic data (Gohl
et al., 1997b; Uenzelmann-Neben and Gohl, 2012). The original volume
of MBS magmatism, however, remains unclear because of incomplete
data and the largely unknown initial volume of the eroded islands.
Based on the available bathymetric data (multi-beam and satellite
gravity), the total volume of all present MBS can roughly be estimated
to more than 20,000 km3. The aerial extent of the former Marie Byrd
Islands were similar in size to Canary Islands, such as La Palma
(compared to Hubert Miller Seamount) or El Hierro (compared to
Table 1
Morphological features of the Marie Byrd Seamounts.
Seamount 6
Seamount 9
Haxby Seamount
Hubert Miller Seamount
Seamount C
Coordinates (center)
Shape
Secondary features
69°47′S, 126°17′W
Oval shaped guyot
Small cones on flanks
and plateau
69°40′S, 124°45′W
Oval shaped guyot
Small cones on flanks and
plateau; WNW–ESE
trending rift zone
69°17′S, 121°20′W
Oval shaped guyot
Small cones on flanks and
plateau; several rift zones,
most of them ~SW–NE
Base level (mbsl)
Diameter at base (km)
Water depth of plateau (mbsl)
Edifice height (m)
Volume estimate (km3)
Dredge samplesa
3000–2800
80 × 20
1600–1350
~1650
~2000
–
3600–3400
Long axis 25
1600–1400
~2200
–
–
69°07′S, 123°35′W
Oval shaped guyot
Small cones on flanks and
plateau; WNW–ESE trending
major rift zone, minor W–E
and WSW–ENE rifts
4000
30
1800–1600
~2400
~1600
PS69/317-1
69°12′S, 117°30′W
Crudely circular guyot
Small cones on flanks and
plateau; rift zones mainly
trending from SSW–NNE to
SSE–NNW
3500
17
2400–2200
~1300
~200
PS69/327-1
a
A detailed description of dredge operations and recovered material is provided in Gohl (2007).
4000–3600
75 × 50
1600–1200
~2800
~8000
PS69/321-1
PS69/324-1
PS69/325-1
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Fig. 3. (a) Overview of the Marie Byrd Seamount Province. Red arrows mark the MBS surveyed during R/V Polarstern cruise ANT-XXIII/4 in 2006, letters in bold signify those which
have been successfully dredged. Predicted bathymetry is after Smith and Sandwell (1997). (b) Multi-beam bathymetry of the eastern part of Seamount 6. This is the westernmost
studied during ANT-XXIII/4 and has not been mapped before. It appears to be one of the largest MBS. (c) Haxby Seamount (named by the ANT-XIII/4 cruise participants) has
completely been mapped on the R/V N.B. Palmer cruise in 1996 and morphologically studied in detail by Feldberg (1997). (d) Combined ANT-XVIII/5a (2001) and ANT-XXIII/4
multi-beam bathymetry of Hubert Miller Seamount. This Seamount is located ~40 nm ESE of Haxby and appears to be the largest of the MBS. (e) Combined ANT-XVI/3 (Miller
and Grobe, 1996) and ANT-XXIII/4 multi-beam bathymetry of Seamount C. This seamount does not appear in the bathymetric maps derived from satellite gravity data. Note
that Seamount C differs in size, high, and morphology from the other surveyed MBS guyots. The red dots with numbers mark dredge station of cruise ANT-XXIII/4 which yielded
in situ volcanic rocks.
Seamount 6), which are believed to be the product of a mantle plume
(e.g., Montelli et al., 2006).
The submarine base of Peter I Island was only partially surveyed
prior to ANT-XXIII/4 and, except for dredge hauls directly off the
coast of the island (Broch, 1927), un-sampled (Fig. 4). The island is
elongated in N–S direction and represents the top of a large volcano,
which measures ~ 65 km in diameter at its base and rises from the
abyssal plain at ~3500–4000 m to an elevation of 1640 m above sea
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
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Fig. 4. Multi-beam bathymetry of the base of Peter I Island. The map reveals several small cone- and ridge-like structures on its flanks and a steep canyon at its eastern side which
most likely has been formed by slope failure or sector collapse. The red dots indicate locations sampled during cruise during R/V Polarstern cruise ANT-XXIII/4 in 2006 (244 — dredge
station at the eastern base of Peter I Island; PI 1–4 — subaerial samples taken on Michajlovodden Peninsula).
level. Volcanic rifts emanate from the submarine flank of the island mainly in northern and southern directions. A striking feature of Peter I Island
is a c. 9 km wide depression in the eastern flank of its base, which most
likely has been formed by a major slope failure or sector collapse.
4. Sample background
Volcanic rocks were recovered at five dredge stations of the main
MBS edifices and associated small cones (Fig. 3b–e). In addition a
single dredge haul along the northeastern submarine flank of Peter I
Island has been carried out (Fig. 4). At all dredge sites discussed here,
the angular shape of the rocks, freshly broken surfaces and homogeneity of rock types within a single dredge were taken as evidence for an
in-situ origin (and non-ice rafted) of the rocks. Our samples represent
the first in-situ volcanic rocks recovered from the MBS. A detailed description of dredge operations and recovered material is provided in
chapter 7 of Gohl (2007).
At Haxby Seamount, dredge haul PS69-317-1 from the upper southern slope beneath the plateau edge contained freshly broken carbonate
cemented breccias, which consist of aphyric basaltic clasts up to 8 cm
in size (Fig. 5a). At Hubert Miller Seamount, three dredges yielded mainly lava fragments; dredge PS69-321-1 along a steep slope below the SE
plateau edge gave olivine (ol)–clinopyroxene (cpx)–phyric lava Fig. 5b,
dredge PS69-324-1 at the lower SE slope beneath a cone like structure
provided dense feldspar (fsp)–cpx–phyric basalt lava and (carbonate)
cemented Mn-encrusted volcanic breccia, and dredge PS69-325-1
obtained vesicular fsp–phyric lava from the upper southern flank. At
Seamount C, vesicular ol–fsp–phyric and dense fsp–phyric pillow fragments (Fig. 5c) were dredged from a cone on the lower western flank.
At Peter I Island, a 150 m high ridge located in ~ 1800 m water
depth on the NE slope of the volcano was dredged (PS69-244-1).
The rocks are predominantly vesicular pillow and sheet flow lava fragments (Fig. 5d). Both are feldspar (fsp)–phyric and have up to 1 cm
thick, fresh, glassy rims. Vesicles are generally unfilled and only a few
glassy surfaces show early stages of palagonitization. The subaerial
samples from Peter I Island were taken at the Michajlovodden Peninsula
(Fig. 4). They comprise vesicular lava (up to 15% vesicles; sample PI-1),
aphyric agglutinates of a N 1.5 m thick, partially red oxidized layer outcropping in the northern part of the peninsula (sample PI-3), and part of
a reddish volcanic bomb with 10–20% vesicles (sample PI-4).
Belgica Seamount is the easternmost edifice of the De Gerlache
Seamount group. It is guyot-shaped and has a N–S elongated base diameter of c. 60 × 90 km with a flat-topped summit at c. 400–500 m
below sea level. Belgica was dredge-sampled during Polarstern
cruise ANTXII-4 in 800 to 600 water depths (Hagedorn et al., 2007).
Hagedorn et al. (2007) initially determined K–Ar ages and major
and trace element geochemistry on the recovered samples. Here
we complement the existing data with Sr–Nd–Pb isotope data on a
subset of newly prepared sample material.
5. Petrography and rock classification
The petrography of the MBS volcanics is quite uniform being
slightly phyric with a few large phenocrysts of altered olivine and
zoned plagioclase in a fine-grained groundmass of olivine, plagioclase
and clinopyroxene. Occasionally, ilmenite and magnetite occur as
accessory phases. Olivine is commonly altered to iddingsite and the
latter is sometimes replaced by calcite. The groundmass is variably
altered by low temperature processes ranging from hydrated glass
at Haxby Seamount to replacement by secondary minerals such as
zeolite and dolomite at Hubert Miller Seamount and Seamount C.
The altered state of the MBS volcanic rocks is also manifested in elevated H2O contents of up to 2 wt.% in most samples, except that samples from Dredge 324 at Hubert Miller Seamount have b1 wt.% H2O
and those from Seamount C have 3 wt.% H2O (Table 2). CO2 contents
are generally low (b0.3 wt.%) and only two samples show slightly elevated CO2 N 0.5 wt.%, due to secondary carbonate. Unusually high
phosphorous contents were detected in 5 samples (marked with a
in Table 2) and are interpreted to reflect the presence of secondary
phosphate that is, however, not detected in thin section. Only samples
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Fig. 5. Basaltic rocks dredged at the MBS and the submarine base of Peter I Island. (a) Typical monomict breccia from Haxby Seamount composed of dense, aphyric irregular-shaped
and angular coarse lapilli set in a carbonaceous matrix (PS69/317-1). (b) Dense ol–cpx–phyric basaltic lava fragment from Hubert Miller Seamount, note angularity and freshly
broken surfaces of the sample (PS69/321-1). (c) Dense fsp–phyric pillow fragment of Seamount C (PS69/327-1). (d) Sheet lava flow fragment with fresh, 1 cm thick glassy rim
from the submarine base of Peter I Island (PS69/244-1).
with P2O5 ≤ 1 wt.% are considered meaningful when treating the major
element chemistry further below.
The submarine samples of Peter I Island are slightly porphyric
with zoned plagioclase laths and small, homogeneously distributed
clinopyroxene phenocrysts, set in a microcrystalline groundmass of
clinopyroxene and plagioclase. Magnetite occurs as an accessory mineral and fresh glass is common. The subaerial volcanics of Peter I Island are
more aphyric than those from the submarine flanks. The fine-grained
crystalline groundmass of these samples contains pyroxene, plagioclase
and possibly glass, and accessory minerals of magnetite, ilmenite and
hematite. All samples from Peter I Island are generally very fresh as
manifested by low H2O (0.3–0.9 wt.%) and CO2 (b 0.06 wt.%) contents
(Table 2).
The silica content of the entire sample suite ranges from 53.1 to
45.7 wt.% SiO2. On a total alkali vs. silica diagram (TAS; Fig. 6), the majority of the samples plots above the alkalic–sub-alkalic division line
and are classified as basalts, trachybasalts and basaltic trachyandesites.
All but one of MBS samples lie along an alkali basaltic differentiation
trend. The samples from the submarine flank of Peter I Island are tholeiitic basalts (SiO2 ~ 49 wt.%; Na2O + K2O 4.1–4.3 wt.%), whereas the
subaerial samples are slightly more alkaline transitional tholeiites
(SiO2 ~ 47 wt.%; Na2O + K2O 4.3–4.5 wt.%).
6. Analytical results
6.1. 40Ar/39Ar age dating
The 40Ar/39Ar age dating results are summarized in Table 3. Age
and alteration index spectra (based on the measured 36Ar/37Ar ratios
after Baksi, 2007) are shown in Fig. 7. A detailed description of the
methods and the full analytical data are provided in Appendix 1.
Glasses from two hyaloclastite breccia samples at Haxby Seamount
yield plateau ages of 64.2 ± 0.9 Ma (317-1-1gls) and of 62.3 ± 0.4
(317-1-2gls) and 61.2 ± 0.5 Ma (317-1-2gl2), slightly outside of the
two sigma analytical errors. Alteration indices are relatively high even
in the plateau sections (0.001 to 0.01), reflecting partial hydration of
the basalt glass and uptake of atmospheric 36Ar.
Three samples of porphyric lava from Hubert Miller Seamount
yield plagioclase step-heating plateau ages of 56.7 ± 1.9 Ma
(321-1-2), 56.5 ± 0.6 Ma (325-1-2B) and 57.0 ± 0.9 Ma (321-1-5).
Alteration indices are high in the low-temperature heating steps indicating partial alteration of the feldspars, but systematically low in the
plateau steps (b0.0002) indicating degassing from little or un-altered
sites. Matrix step-heating analyses from the same rock samples yield
plateau age results within error of the feldspar step-heating results
(321-1-2: 58.9 ± 0.6 Ma; 321-1-5: 55.7 ± 0.5 Ma), but are considered inferior with respect to scatter and alteration effects.
The matrix step-heating analysis of aphyric basalt lava sample
324-1-3, in contrast, yields a plateau age of 3.0 ± 0.5 Ma. Alteration
indices are high in the plateau section (0.003 to 0.01), possibly indicating
a partial loss of radiogenic 40Ar. Nevertheless, the analysis shows that
Hubert Miller Seamount comprises both Paleocene and Pliocene lavas.
The least-altered aphyric lava sample from Seamount “C” (327-1-2)
yields a low-probability plateau age of 58.7 ± 0.8 Ma, with intermediate plateau-step alteration indices (0.002 to 0.008). Fresh basaltic glass
from Peter I Seamount yields plateau steps alteration indices of b0.0009
(244-1-1) and b 0.0001 (244-1-3), and plateau ages of 1.9 ± 0.3 Ma,
1.7 ± 0.3 Ma respectively.
6.2. Major and trace elements
A total of 19 samples from the MBS and Peter I Island were analyzed for major and trace elements compositions and the results are
Table 2
Results of major and trace element analyses.
PS69/317-1-1
Haxby Smt
a
46.13
3.39
16.33
14.81
0.21
3.46
7.72
3.82
1.54
0.91
1.91
0.06
100.29
28.1
330
4.79
1.52
70.3
4.21
49.6
106
2.75
13.1
55.6
760
12.1
8.06
404
3.79
10.8
1.45
7.98
1.43
42.3
3.59
0.457
3.13
0.450
PS69/317-1-2
Haxby Smt
PS69/321-1-2
Hubert Miller Smt
PS69/321-1-4
Hubert Miller Smt
PS69/321-1-5
Hubert Miller Smt
PS69/321-1-12a
Hubert Miller Smt
PS69/324-1-3
Hubert Miller Smt
PS69/324-1-4
Hubert Miller Smt
PS69/324-1-6
Hubert Miller Smt
28.1
330
4.72
1.52
70.6
4.18
48.9
106
2.35
13.1
55.2
756
12.1
8.02
402
3.75
10.7
1.47
7.89
1.46
42.0
3.72
0.479
3.14
0.447
42.03
3.57
18.2
15.91
0.21
3.41
9.02
3.51
0.74
1.44a
2.38
0.17
100.59
6.66
264
4.60
0.427
68.1
4.27
64.4
114
2.41
14.4
57.6
1219
13.3
8.35
413
4.14
11.4
1.56
8.36
1.54
51.6
3.84
0.475
3.84
0.554
50.22
1.89
17.15
11.49
0.22
2.58
6.39
4.57
2.61
0.73
2.23
0.30
100.38
53.4
725
6.89
1.75
123
6.60
76.8
154
3.81
17.0
63.2
825
12.6
8.83
475
3.92
10.2
1.40
7.50
1.33
43.6
3.47
0.455
3.54
0.496
46.23
3.59
17.59
14.19
0.19
2.85
8.84
3.54
2.09
0.92
1.80
0.08
101.91
37.3
462
4.57
0.816
78.5
4.59
52.4
106
2.44
12.2
46.0
969
9.86
6.36
323
3.09
8.00
1.05
5.40
0.97
32.5
2.49
0.310
2.57
0.359
45.95
3.44
16.62
13.95
0.22
3.96
8.44
3.53
2.05
0.79
1.86
0.07
100.88
50.4
493
4.43
0.695
77.2
4.45
51.4
103
2.65
11.6
44.3
925
9.49
5.94
317
2.91
7.45
0.979
5.04
0.92
31.5
2.31
0.291
2.45
0.332
50.19
2.09
18.46
11.09
0.17
2.07
6.76
4.53
2.15
0.87
2.10
0.07
100.55
23.9
784
7.31
0.296
119
6.97
65.9
146
3.37
16.1
61.6
891
12.5
9.36
446
4.12
9.66
1.29
6.58
1.14
35.5
2.79
0.345
2.76
0.366
45.80
2.60
15.02
13.05
0.19
8.13
10.65
3.29
1.04
0.48
0.74
0.13
101.12
24.1
311
2.99
0.743
46.0
2.78
32.1
66.2
2.47
7.74
30.1
626
6.69
4.30
205
2.19
5.89
0.814
4.38
0.787
25.2
2.07
0.261
2.08
0.278
52.85
0.85
17.18
8.63
0.18
5.52
8.68
3.99
1.45
0.21
0.98
0.07
100.59
35.8
455
4.72
0.819
78.5
4.60
53.1
107
2.30
12.3
46.5
967
9.97
6.35
321
3.04
8.10
1.02
5.49
0.971
31.6
2.50
0.325
2.49
0.350
46.74
3.26
14.86
14.73
0.20
4.87
10.31
3.65
1.24
0.54
0.82
0.08
101.30
28.0
320
3.91
0.982
56.6
3.39
38.3
78.4
1.89
8.98
35.5
568
8.08
5.55
261
2.49
7.17
1.02
5.74
1.02
31.8
2.66
0.350
2.65
0.364
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
SiO2
TiO2
Al2O3
Fe2O3
MnO
MgO
CaO
Na2O
K2O
P2O5
H2O
CO2
Total
Rb
Ba
Th
U
Nb
Ta
La
Ce
Pb
Pr
Nd
Sr
Sm
Hf
Zr
Eu
Gd
Tb
Dy
Ho
Y
Er
Tm
Yb
Lu
PS69/317-1-1
Replicate ICP-MS
Results with unusual high values not shown in Fig. 6.
1667
1668
PS69/325-1-2b
Hubert Miller Smt
PS69/327-1-1
Seamount C
PS69/327-1-2
Seamount C
PS69/244-1-1
Peter I submarine
PS69/244-1-3
Peter I submarine
PS69/244-1-5
Peter I submarine
PS69/PI-1
Peter I subaerial
PS69/PI-3
Peter I subaerial
PS69/PI-4
Peter I subaerial
47.72
2.52
16.78
11.58
0.14
2.54
7.93
3.88
2.74
1.69a
2.12
0.59
100.23
90.1
469
6.93
1.34
95.6
5.38
73.5
141
3.38
16.3
62.4
674
12.9
7.99
412
3.59
10.9
1.48
7.39
1.35
48.7
3.50
0.458
3.63
0.515
47.72
2.49
17.24
12.02
0.14
1.34
7.40
4.19
3.24
2.12a
2.13
0.18
100.21
57.3
480
7.02
1.33
96.8
5.44
73.8
144
3.21
16.3
62.3
717
13.3
8.02
417
3.56
10.9
1.41
7.51
1.36
46.1
3.52
0.449
3.54
0.506
41.98
2.26
18.15
8.92
0.08
0.97
12.84
3.55
1.74
5.02a
2.92
0.56
98.99
27.2
404
5.21
1.78
55.6
3.48
66.2
80.4
3.07
10.4
39.0
811
8.09
4.99
250
2.45
7.78
1.07
6.32
1.33
66.5
3.71
0.509
4.21
0.674
46.00
2.70
20.31
11.30
0.15
1.24
8.73
3.44
1.38
1.62a
3.03
0.24
100.14
21.5
427
5.06
1.43
58.7
3.58
44.6
84.5
2.24
9.36
35.6
843
7.89
5.37
258
2.49
6.87
0.957
5.30
0.979
32.0
2.70
0.349
2.72
0.377
49.48
2.79
13.68
12.58
0.14
8.18
9.00
3.17
1.16
0.50
0.86
0.05
101.59
20.3
240
2.85
0.887
30.2
1.88
27.2
58.5
2.30
7.49
32.7
624
7.57
5.22
233
2.43
6.78
0.874
4.69
0.792
22.5
1.83
0.226
1.53
0.192
49.09
2.74
13.26
12.55
0.15
9.2
8.68
3.03
1.08
0.51
0.87
0.05
101.21
19.8
228
2.68
0.725
29.4
1.83
26.7
57.1
2.26
7.20
30.8
622
7.54
5.19
230
2.48
6.55
0.882
4.54
0.737
21.6
1.72
0.207
1.50
0.193
49.26
2.75
13.61
12.85
0.14
8.55
8.91
3.00
1.15
0.48
0.94
0.06
101.70
19.2
226
2.57
0.704
28.9
1.76
26.1
55.6
2.22
6.95
29.2
632
7.48
5.03
227
2.39
6.38
0.854
4.40
0.706
21.6
1.73
0.204
1.49
0.186
47.79
3.53
12.79
13.48
0.15
9.64
9.03
3.07
1.37
0.64
0.28
0.04
101.81
23.9
308
3.53
0.920
48.5
2.82
38.0
80.9
2.26
10.2
43.1
797
9.80
7.03
315
3.14
8.50
1.14
5.70
0.924
24.9
2.14
0.255
1.58
0.206
47.26
3.48
12.52
13.36
0.15
9.86
8.83
3.03
1.42
0.69
0.45
0.04
101.09
26.5
315
3.74
0.984
48.7
2.89
40.3
85.2
2.46
10.4
43.6
804
10.2
7.42
326
3.21
8.63
1.13
5.52
0.894
24.9
2.05
0.246
1.54
0.209
48.15
3.46
12.73
13.03
0.14
9.42
8.67
3.17
1.47
0.78
0.38
0.04
101.44
26.3
332
3.78
1.02
50.6
2.90
43.1
92.4
2.31
11.4
48.5
871
11.0
7.59
344
3.52
9.61
1.19
5.85
0.963
25.7
2.14
0.256
1.56
0.203
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
SiO2
TiO2
Al2O3
Fe2O3
MnO
MgO
CaO
Na2O
K2O
P2O5
H2O
CO2
Total
Rb
Ba
Th
U
Nb
Ta
La
Ce
Pb
Pr
Nd
Sr
Sm
Hf
Zr
Eu
Gd
Tb
Dy
Ho
Y
Er
Tm
Yb
Lu
PS69/325-1-2a
Hubert Miller Smt
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
1669
The new trace element data from Peter I Island also display trace
element patterns similar to OIB (Fig. 8b) that compares well with the
data of Prestvik et al. (1990) and Hart et al. (1995). Overall the subaerial
samples are slightly more enriched in incompatible elements than the
submarine sample but show similar HREE abundances (Fig. 8d), which
is consistent with lower degrees of melting for the subaerial lavas. In
contrast to the MBS, Peter I Island samples are slightly less enriched in
LREE and the most incompatible elements (Rb through Ta) and show
lower La/Sm ratios (Fig. 9a), indicating higher degrees of partial melting
than observed for the MBS. Notably the LREE are more strongly enriched
relative to the HREE through a more pronounced HREE depletion. The
higher (Sm/Yb)n ratios of the Peter I Island melts suggest that their
source had a higher garnet content (Fig. 9b).
6.3. Sr–Nd–Pb–Hf isotopes
Fig. 6. Total alkali versus SiO2 diagram illustrating the alkali basaltic to basaltic
trachyandesitic composition of most samples from MBS, Peter I Island, and Belgica Seamount.
Subdivision between alkalic and sub-alkaline rock suites is after Irvine and Baragar (1971).
All data are normalized to a 100% volatile free basis. Samples displaying unusual high phosphor contents are not shown in this diagram (cf. Table 2). Tb — Trachybasalt.
shown in Table 2. Descriptions of methods and uncertainties are given
in Appendix 1. A full table with sample locations, radiometric ages and
geochemical data is provided in Table A4 of the Appendix. The majority
of MBS samples are fairly evolved (8 to 2 wt.% MgO), whereas samples
from Peter I Island are more primitive and cluster between 10 and
8 wt.% MgO. Al2O3 shows a good negative correlation with decreasing
MgO, suggesting fractionation of pyroxene and olivine. In the most
evolved MBS lavas (b3 wt.% MgO), FeOt and TiO2 significantly decrease
which may reflect fractionation of ilmenite in late stage melts. Subaerial
and submarine samples of Peter I Island exhibit small compositional
differences. The submarine samples have higher SiO2 and Al2O3 and
slightly lower MgO, FeOt and TiO2 contents than the subaerial samples.
Trace elements patterns of the MBS are typical for ocean islands
basalts (OIB; Fig. 8a) with characteristic troughs for Pb and K and
strong enrichments for Nb and Ta relative to primitive mantle. The
Nb and Ta enrichments are most pronounced in samples from Hubert
Miller Seamount while Haxby Seamount and Seamount C are less
enriched in the most incompatible elements (Rb, Ba and Th). All MBS
samples show strong enrichment of the light REE (LREE) relative to
the heavy REE (HREE) (see Fig. 8c), suggesting small degrees of partial
melting while differentiation of the HREE indicates melting within the
garnet stability field (N70–80 km).
Sr–Nd–Pb–Hf isotopic ratios of representative samples from the
MBS, Belgica Seamount, and Peter I Island are shown in Table 4.
Descriptions of analytical methods and accuracy along with initial
isotopic ratios are given in Appendix 1 and Table A4. Figs. 10 and 11
compare the new MBS, Peter I Island and Belgica Seamount isotope
data with data of West Antarctic volcanic rocks, related to the WARS
(for data sources see figure captions) and the Hikurangi Seamounts
(Hoernle et al., 2010). Excluding two samples with anomalously high
87
Sr/86Sr isotope ratios that may have been affected by seawater alteration, the MBS samples form a crude negative array on the Sr–Nd isotope diagram (Fig. 10). The samples from Seamount C have the most
radiogenic Nd and least radiogenic Sr isotope ratios and fall between
Pacific MORB and the high 238U/204Pb (HIMU) mantle endmember.
Samples from Hubert Miller Seamount have the least radiogenic Nd
isotope ratios and trend vaguely towards an enriched mantle (EM)
type component (Fig. 10). The Belgica samples plot within the Pacific
MORB field and the Peter I Island samples lie within the published
field for this island (Prestvik et al., 1990; Hart et al., 1995) and are
displaced to slightly more radiogenic Sr and less radiogenic Nd isotope
ratios i.e. to faintly more EM flavored compositions than the majority of
Hubert Miller Seamount samples. In Pb–Pb isotope space (Fig. 11a), the
MBS volcanic rocks do not form a simple two component mixing array
as the majority of samples extends from a HIMU-type component
with radiogenic Pb towards enriched mantle one (EMI) while two samples having significantly lower 207Pb/204Pb which displaces them towards the extension of the Pacific MORB field. Sample 324-1-4 from
Hubert Miller Seamount has the least radiogenic Pb composition of all
MBS and plots above the Pacific MORB field away from the main
MBS array while samples from Haxby Seamount possess the most radiogenic Pb composition. The Belgica Seamount samples plot near
the unradiogenic end of the main MBS field in Pb–Pb isotope space
(Fig. 11a) but possess more radiogenic 143Nd/144Nd compositions
than the MBS (Fig. 11b). The majority of MBS samples and all Belgica
Table 3
40
Ar/39Ar step heating analyses results.
Seamount
Sample ID PS69-
Analysis ID
Dated material
Plateau ± 2 sigma age
(Ma)
39
Haxby
317-1-1
317-1-2
317-1-2
321-1-2
321-1-2
321-1-5
321-1-5
325-1-2B
324-1-3
327-1-2
244-1-1
244-1-3
gls
gls
gl2
fss
mx2
fss
mx2
fss
mxs
mx2
gls
gl2
Glass
Glass
Glass
Plag
Matrix
Plag
Matrix
Plag
Matrix
Matrix
Glass
Glass
64.7
62.3
61.2
56.7
58.9
57.0
55.7
56.5
3.0
58.7
1.9
1.7
63.1
56.8
72.9
73.9
95.6
58.4
63.5
61.1
84.6
55.7
83.8
96.4
Hubert Miller
“C”
Peter Ia
a
Dated samples from Peter I Island are dredge samples from its submarine base.
±
±
±
±
±
±
±
±
±
±
±
±
0.8
0.4
0.5
1.9
0.6
0.9
0.5
0.6
0.5
0.8
0.3
0.3
Ar fraction
MSWD
Probability
0.95
0.99
1.19
0.61
1.10
1.30
0.78
1.20
1.30
1.90
1.03
0.58
0.46
0.44
0.27
0.72
0.34
0.23
0.45
0.30
0.21
0.04
0.41
0.87
1670
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
Table 4
Sr-Nd-Pb-Hf-Isotope analyses.
87
2 sigma
143
0.703093
0.704186
0.703384
0.703277
0.703335
0.703230
0.703094
0.704027
0.704043
0.703108
0.000003
0.000003
0.000003
0.000002
0.000002
0.000003
0.000003
0.000003
0.000003
0.000003
0.703502
0.703417
0.702888
0.702805
0.702831
De Gerlache Smts.
PS-2693-1_(1)e
PS-2693-1_(2)e
PS-2693-1_(3)e
PS-2693-1_(4)e
PS-2693-1_(5)e
PS-2693-1_(6)e
Peter I Island
PS69/244-1-1
PS69/244-1-3
PS69/PI-1f
PS69/PI-3
PS69/PI-4
Marie Byrd Smts.
PS69/317-1-1
PS69/317-1-2
PS69/321-1-2
PS69/321-1-4
PS69/321-1-5
PS69/321-1-12a
PS69/324-1-3
PS69/324-1-4
PS69/324-1-4d
PS69/324-1-6
PS69/324-1-6d
PS69/325-1-2a
PS69/325-1-2b
PS69/327-1-1
PS69/327-1-2
PS69/327-1-2d
d
Sr/86Sr
Nd/144Nd
2 sigma
206
0.512885
0.512881
0.512798
0.512806
0.512816
0.512811
0.512906
0.512881
0.512870
0.512899
0.000003
0.000003
0.000003
0.000002
0.000003
0.000003
0.000003
0.000003
0.000003
0.000003
0.000003
0.000002
0.000003
0.000003
0.000003
0.512809
0.512817
0.512913
0.512918
0.512927
0.000003
0.000003
0.000006
0.000009
0.000004
0.703015
0.703023
0.703029
0.703029
0.702998
0.702994
0.000005
0.000005
0.000005
0.000004
0.000005
0.000005
0.512967
0.512966
0.512966
0.512957
0.512983
0.512975
0.703748
0.703752
0.703759
0.703837
0.703871
0.000003
0.000003
0.000005
0.000002
0.000002
0.512759
0.512750
0.512805
0.512782
0.512775
Pb/204Pb
2 sigma
207
20.7725
20.4116
20.2467
20.1075
20.1005
19.9595
19.6713
18.7063
18.7110
19.8645
19.8661
20.1218
20.0871
19.8152
19.8530
0.0015
0.0020
0.0016
0.0006
0.0008
0.0008
0.0011
0.0006
0.0006
0.0009
0.0013
0.0008
0.0008
0.0010
0.0008
0.000002
0.000003
0.000003
0.000003
0.000004
0.000003
19.8515
19.8376
19.8278
19.9238
19.7441
19.7447
0.000002
0.000003
0.000002
0.000002
0.000003
19.2360
19.2517
19.3013
19.3015
19.3244
Pb/204Pb
2 sigma
208
15.7739
15.7561
15.7229
15.7153
15.7160
15.7082
15.6140
15.6189
15.6184
15.6339
15.6331
15.7193
15.7180
15.6835
15.6903
0.0016
0.0022
0.0017
0.0006
0.0008
0.0009
0.0013
0.0007
0.0007
0.0009
0.0014
0.0006
0.0006
0.0010
0.0008
0.0021
0.0025
0.0032
0.0037
0.0025
0.0016
15.6878
15.6795
15.6804
15.6834
15.6641
15.6601
0.0015
0.0006
0.0012
0.0007
0.0007
15.7437
15.7520
15.7216
15.7409
15.7456
Pb/204Pb
2 sigma
176
Hf/177Hf
40.1472
39.9679
40.0393
39.9521
39.9815
39.9274
39.5216
38.4900
38.4973
39.7163
39.7173
39.9100
39.8863
39.2970
39.3447
0.0056
0.0075
0.0057
0.0018
0.0028
0.0028
0.0044
0.0020
0.0019
0.0027
0.0048
0.0016
0.0017
0.0031
0.0024
0.282871
0.282875
0.282879
0.282880
0.000005
0.000004
0.000003
0.000004
0.282875
0.282787
0.282877
0.000004
0.000007
0.000004
0.283003
0.000004
0.282862
0.000004
0.282927
0.000004
0.0018
0.0021
0.0027
0.0030
0.0024
0.0012
39.5057
39.4705
39.4777
39.4845
39.3550
39.3438
0.0049
0.0056
0.0063
0.0081
0.0069
0.0032
0.0017
0.0006
0.0010
0.0006
0.0006
39.3779
39.4162
39.3230
39.3865
39.4265
0.0056
0.0019
0.0026
0.0015
0.0014
0.282798
0.000003
2 sigma
Replicate analyses.
Sr/86Sr determined on MAT262 TIMS.
Pb isotope ratios without Pb DS.
e 87
f
Seamount samples largely overlap with the fields of the West Antarctic
volcanics and the Hikurangi Seamounts (Fig. 11). The Peter I Island samples overlap the published data from this island and have Pb isotope
compositions near the enriched mantle two (EMII) component.
The above mixing relations are also seen in co-variations of
206
Pb/204Pb versus 143Nd/144Nd (Fig. 11b) and εNd versus εHf
(Fig. 12). On the Pb vs Nd isotope diagram, it is clear that at least three
distinct components are required in the source of the MBS seamounts.
Haxby Seamount has radiogenic Pb and intermediate Nd isotope ratios,
similar to the HIMU mantle endmember. Seamount C and two Hubert
Miller Seamount samples have less radiogenic Pb and intermediate
Nd, trending toward Pacific MORB (or depleted mantle = DM). The
remaining Hubert Miller seamount samples except sample 324-1-4
have radiogenic Pb but the least radiogenic Nd, so that they are somewhat displaced toward EM like compositions. On the Nd–Hf isotope diagram, the MBS seamounts show a relatively restricted range in Nd but
a large range in Hf isotope ratios that fall between Pacific MORB (DM)
and the HIMU and EM mantle endmembers. The Belgica Seamount samples have the most MORB-like compositions in Nd, but their 206Pb/204Pb
isotopic compositions are more radiogenic than commonly found in
MORB. The Peter I Island samples have a clear EMII-type isotope signal
with respect to Pb while Sr, Nd and Hf isotopes are just EM indicative.
7. Discussion
7.1. Spatial distribution of Cenozoic volcanism in the Amundsen Sea and
Bellingshausen Sea
40
Ar/39Ar dating of six samples from the MBS yielded Early Cenozoic
ages ranging from 64 to 57 Ma. A clear spatial age progression between
the three dated MBS is not observed. The oldest ages are from Haxby
Seamount in the west (64–61 Ma) and clearly younger ages are from
Hubert Miller Seamount to the east (57 Ma, three feldspar ages).
Seamount C, the easternmost seamount, yielded an intermediate
age (59 Ma), but this matrix age with a very low probability should
be treated with caution. The Pliocene age of 3.0 ± 0.5 Ma determined for sample 324-1-3 was collected right beneath a small volcanic cone along the upper slope of Hubert Miller Seamount (Fig. 3d)
and most likely represents the age of this cone. Similar cones are
scattered on the plateau and slopes of all mapped MBS (cf. Fig. 3), indicating widespread and possibly long-lasting low volume post-erosional
volcanism, as has been observed at other seamount provinces worldwide
(e.g., Hoernle et al., 2004; Geldmacher et al., 2005; Hoernle et al., 2010).
Assuming that the 40Ar/39Ar ages obtained at the three MBS are
close (within a few million years) to the time when these islands
were eroded and submerged below sea-level, a minimum subsidence
rate can be calculated for each seamount taking the age and present
water depth of the plateau of the seamount into account. Seamount
C, the smallest and deepest edifice, displays the highest subsidence
rate of ~ 41 m/Ma if it is actually a guyot. In contrast, the larger
Haxby and Hubert Miller Seamounts both yield minimum subsidence
rates of ~ 28 m/Ma despite their apparent age difference of ~ 5 Ma. We
note that the plateau edges of the westernmost Seamounts 6 and 9 lie
at roughly similar water depth (1600–1350 m, Table 1) as observed
for Haxby and Hubert Miller Seamounts (1800–1200 m), which in
turn may indicate a comparable subsidence history provided similarities in lithospheric age and structure west of Haxby Seamount as well
as analogous formation ages of 60 ± 5 Ma.
The new ages (1.9 ± 0.3 Ma to 1.7 ± 0.3 Ma) for samples from
the eastern submarine flank of Peter I Island are significantly older
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
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Fig. 7. Age spectra and alteration indices (A.I.) from 40Ar/39Ar laser step-heating experiments. Plateau steps and corresponding range of alteration index values are accentuated by
gray shading. Stated errors are ±2σ.
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A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
Fig. 8. Multi-element diagram normalized to primitive mantle after Hofmann (1988) for (a) MBS and (b) Peter I Island samples. The trace elements patterns of all the samples are
similar to those of ocean islands basalts (OIB). OIB and E-MORB patterns are after Sun and McDonough (1989). REE diagrams normalized to C1 are after McDonough and Sun (1995)
for (c) MBS and (d) Peter I Island samples.
Fig. 9. (Sm/Yb)n (n = normalized to primitive mantle after Hofmann, 1988) versus
(a) La/Sm and (b) Zr/Hf ratios. Lower La/Sm ratios indicate slightly higher degrees of partial
melting for Peter I Island and Belgica Seamount than for MBS. Residual garnet and pyroxene
and/or eclogite in the magma source is indicated by high (Sm/Yb)n ratios of 2 to 8 and relatively high Zr/Hf ratios (N40), respectively. Zr/Hf ratios for depleted MORB mantle (32–40)
are after Salters and Stracke (2004) and Workman and Hart (2005).
Fig. 10. 87Sr/86Sr versus 143Nd/144Nd isotope correlation diagram for MBS, Peter I Island, and Belgica Seamount samples. Symbols are as in Fig. 9. The field for West Antarctic volcanics is defined by data of the WARS (Rocholl et al., 1995; Rocchi et al., 2002a),
the Jones Mountains in Ellsworth Land (Hart et al., 1995), and the Marie Byrd Land Volcanic Province (Hart et al., 1997; Panter et al., 1997, 2000), which extends along the Pacific margin of Marie Byrd Land. Most authors consider the volcanism at the Marie Byrd
Land Volcanic Province and Jones Mountains as related to the WARS (e.g., Hart et al.,
1995, 1997; Panter et al., 2000). The field for the Hikurangi Seamounts is based on
data by Hoernle et al. (2010), published data for Peter I Island comprise analyses of
subaerial basaltic lavas from Prestvik et al. (1990) and Hart et al. (1995). The field for
Cretaceous volcanics of New Zealand is based on Tappenden (2003); Panter et al.
(2006) and McCoy-West et al. (2010). HIMU, EM I, and EM II are after Zindler and
Hart (1986) and Hart et al. (1992). Fields for Pacific MORB are from PetDB (http://
www.earthchem.org/petdb) based on analyses of fresh glass.
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
1673
since ~ 2 Ma at Peter I Island. The three seamount/ocean island groups
are spatially arranged in a highly elongated triangle with the MBS
lying at its western tip and the De Gerlache Seamounts and Peter I Island forming the eastern limit (Fig. 1). The age distribution neither
shows a correlation with spatial distribution nor a correlation with
the age of the underlying ocean crust (e.g., Eagles et al., 2004a). A relationship between ages and plate motion cannot be observed, because neither the relative motion between the Bellingshausen Plate
and the Antarctic Plate nor the absolute plate motion of the Antarctic
Plate was significant for this time period (Eagles et al., 2004a,b;
Wobbe et al., 2012; Doubrovine et al., 2012).
Therefore, the irregular spatial distribution of seamount ages in the
Amundsen Sea and Bellingshausen Sea indicates that this magmatism
occurred at distinct time intervals in spatially confined areas. This observation excludes an origin through a single stationary hotspot sensu
Morgan (1971). Instead this regional age pattern of intraplate volcanism favors the presence of three melting anomalies independent in
space and time. Before we explore possibilities of non-plume related
intraplate volcanism, we will first briefly reiterate geochemical constraints on the origin of the magma sources.
7.2. Geochemical constraints on the origin of seamount magmatism
Fig. 11. (a) 206Pb/204Pb versus 207Pb/204Pb, and (b) 143Nd/144Nd isotope correlation diagrams for MBS, Peter I Island, and Belgica Seamount samples. Symbols and data
sources are as in Fig. 10.
than earlier published K–Ar ages (327 ± 88 ka to 111 ± 36 ka
[1 sigma errors], Prestvik and Duncan, 1991) obtained on subaerial
samples, which suggests that the fresh pillow glasses belong to an
earlier submarine phase of this volcano.
Together with published Upper Miocene K–Ar ages for the Belgica
Seamount (20–23 Ma, Hagedorn et al., 2007), the three seamount/
ocean island volcanic provinces of the Amundsen and Bellingshausen
Sea appear to have formed at distinct age intervals of 64–57 Ma for
the MBS, at ~ 22 Ma for the De Gerlache Seamounts and at least
Fig. 12. εNd versus εHf isotope correlation diagram for MBS and Peter I Island samples.
Figure modified after Geldmacher et al. (2003), symbols and data sources for Hikurangi
Seamounts and Pacific MORB are as in Fig. 10. The New Zealand Cretaceous field includes Nd values by Tappenden (2003) and Hf values analyzed by Timm et al. (2010)
for the Mandamus Complex, as well as data from McCoy-West et al. (2010) for Lookout
Volcanics.
Lavas of all three seamount provinces (MBS, De Gerlache and Peter
I Island) display a strong enrichment of the LREE relative to the HREE
(Fig. 8c + d), clearly indicating partial melting in the presence of garnet. Likewise (Sm/Yb)N, (Gd/Yb)N and (Dy/Yb)N are all N 1 which, is
consistent with residual garnet in the source (cf. Fig. 9b). Furthermore,
the slight enrichment of Zr relative to Hf on the mantle-normalized
plot (Fig. 8a + b) is also consistent with residual garnet (Hauri et al.,
1994). Consequently, melt segregation in all three areas must have occurred in the garnet stability field N60–80 km or 40–50 km if garnet pyroxenite was in the source (Hirschmann and Stolper, 1996). High
Zr/Hf (43–54, Fig. 9b), Nb/Ta (16–19) and low Zr/Sm (31–38) provide additional support for partial melting of eclogite/garnet pyroxenite (i.e. recycled ocean crust), rather than garnet peridotite,
consistent with a HIMU component in the mantle source.
The isotopic signatures of MBS volcanic rocks are consistent with the
presence of a HIMU-type mantle component in the source of these rocks
(Figs. 10–12). The extremely radiogenic 206Pb/204Pb of the HIMUendmember requires a high 238U/204Pb in the source; a component unlikely to develop in significant amounts within the convecting upper
oceanic mantle without crustal recycling (see Stracke, 2012 for a recent
review). HIMU is classically thought to reflect deep mantle recycling of
oceanic crust by mantle plumes, ascending from deep in the mantle
(Hofmann and White, 1982; White, 2010), however, from the lack of
clear indications for the long-term existence of a classical mantle
plume in the Amundsen Sea it is clear that alternative mechanisms
are required to explain the occurrence of HIMU-type intraplate volcanism in this area, as has also been proposed for HIMU-type volcanic
rocks in New Zealand (Hoernle et al., 2006).
Subaerial and submarine samples of Peter I Island exhibit small
compositional differences with the submarine samples having higher
SiO2 and Al2O3 and slightly lower MgO, FeOt and TiO2 contents than
the subaerial samples. The slight differences in MgO, FeOt, Al2O3
and TiO2 between submarine and subaerial lavas could be related
through fractionation of olivine, pyroxene and possibly ilmenite
from a subaerial melt composition, but this scenario cannot explain
the higher incompatible element abundances in the subaerial lavas.
Along with the slightly more alkaline character of the subaerial lavas
in our sample set, the data indicates that the subaerial lavas could reflect
slightly lower degrees of mantle melting, which would also explain
their higher incompatible element abundances. Variations in the extent
of partial melting are common during the life cycle of ocean island
volcanoes with more alkaline compositions of lavas during the subaerial
stage compared to less alkaline (tholeiitic) compositions during the
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A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
submarine shield stage (e.g., Frey et al., 1990). Even during the submarine stage, short-term variations in the degree of partial melting have
been observed at Loihi Seamount in the Hawaiian Islands (Garcia
et al., 1993).
The Pb isotopic composition of lavas from Peter I Island carries a
clear EM II source signal (Fig. 11a) that is commonly thought to reflect contributions from pelagic sediments or upper continental
crust (e.g., Zindler and Hart, 1986; Willbold and Stracke, 2010). The
mafic composition of Peter I Island lavas, negative Pb anomalies and
high Ce/Pb (~ 25 in submarine samples, 34–40 in subaerial samples)
argue against shallow AFC processes such as sediment assimilation
or preferred leaching of sedimentary Pb. This conclusion is similar
to that of Hart et al. (1995), who explain the high 207Pb/204Pb signature of Peter I Island melts as evidence for the involvement of a mantle plume with EM II characteristics. We also note that the majority of
global pelagic sediments have lower 206Pb/204Pb and 207Pb/204Pb ratios
than observed in the Peter I Island lavas and thus involvement of modern pelagic sediment seems less likely. This is consistent with the Hf–Nd
isotope ratios, which show that marine sediments did not influence the
submarine sample of Peter I Island (Fig. 12). Ce/Pb lying within (or
slightly above) the canonical array of 25 ± 5 for global OIB and MORB
(after Hofmann et al., 1986) provides additional evidence for derivation
from oceanic mantle rather than involvement of continental crust,
which has Ce/Pb of 3–5. The solitary location of Peter I Island suggests
that magmatism is related to a localized upwelling of EMII-like mantle
but it is unclear whether this is connected to a blob rising from a thermal boundary such as the SW Pacific superswell or melting of a continental raft that drifted into the oceanic upper mantle during the final
Gondwana breakup.
In summary, Cenozoic intraplate volcanism in the Amundsen Sea
and Bellingshausen Sea requires involvement of depleted MORB mantle in the source with significant contributions of enriched components of HIMU and EM affinity. Due to the lack of clear evidence for
the existence of a mantle plume in this region, a model is needed to
explain the evidence for enriched (plume like) components in the
source of Amundsen Sea intraplate volcanism and a non-plume related process to accomplish adiabatic mantle melting in an intraplate
environment.
7.3. Origin of the HIMU component in non-hotspot related
Southwest-Pacific and Antarctic volcanic provinces
Alkalic volcanism with HIMU-like incompatible-element and isotopic signatures, similar to the samples from MBS, is reported from
numerous locations throughout the SW Pacific and West Antarctica.
These include the Chatham Rise, Hikurangi Seamounts, intraplate volcanic fields in New Zealand, sub-Antarctic islands and West Antarctica
Fig. 13. Schematic sketch placing the origin of the MBS in a regional geodynamic context. (a) During the final stage of subduction of the Pacific Plate beneath the Zealandia/
West Antarctic Gondwana margin, the Hikurangi Plateau approaches the subduction
zone. (b) Forces acting upon the plate margin as, for example, the collision of the
Hikurangi Plateau with Zealandia (e.g., Bradshaw, 1989; Davy et al., 2008) cause cessation of subduction and slab detachment. The impact of a plume head at that time was
accompanied by large scale underplating of HIMU material beneath East Gondwana
(e.g., Weaver et al., 1994; Hart et al., 1997) and the Hikurangi Plateau (possibly by deflection of the plume material by the subducting plate; Hoernle et al., 2010), triggering
volcanism on West Antarctica and Zealandia and the formation of the Hikurangi Seamounts. (c) After subduction ended, extensional processes set in, causing the break-up
of Zealandia from Marie Byrd Land at ~90 Ma and subsequent rifting, forming the oceanic
crust of the Amundsen Sea (Eagles et al., 2004a). (d) Lateral temperature differences between warm mantle beneath the continental lithosphere and normal upper mantle drove
continental-insulation flow (model modified after King and Anderson, 1995), allowing
sub-continental mantle material to rise into the upper mantle beneath the adjacent oceanic
lithosphere. At the Cretaceous/Tertiary boundary lithospheric extension at the southern
margin of the Bellingshausen Plate (e.g., Wobbe et al., 2012) formed deep reaching faults
that allowed rise of plume type melts and formation of the MBS from a magma source
similar to that of the Hikurangi Seamounts and the West-Antarctic/Zealandia volcanoes.
For further details and references see text.
(e.g., Weaver and Pankhurst, 1991; Baker et al., 1994; Weaver et al.,
1994; Rocholl et al., 1995; Hart et al., 1997; Panter et al., 2000;
Tappenden, 2003; Panter et al., 2006; Nardini et al., 2009; Hoernle
et al., 2010). In all these localities, volcanic centers are diffusely distributed and do not show any age progression relative to plate motion.
Most commonly, models suggest localized extension/upwelling of asthenosphere that induces melting of metasomatized lithosphere in
thin spots to produce the diffuse alkaline magmatism.
Finn et al. (2005) postulate a “diffuse alkaline magmatic province
(DAMP)”, which formed without any rifting or plume upwelling. They
temporally extend the DAMP into the Cenozoic and explain this
magmatism by detachment of subducted slabs from the base of Gondwana lithosphere in the late Cretaceous. The sinking of material into
the mantle is thought to have introduced Rayleigh Taylor instabilities
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
along the Gondwana margin and activated lateral and vertical flow of
warm Pacific mantle. After Finn et al. (2005) the interaction of the
warm mantle with metasomatized lithosphere generated the HIMU
geochemical characteristics of the DAMP. A shortcoming of this model
is, however, that Finn et al. (2005) had to focus their study on old, continental fragments of East Gondwana, and could not include oceanic occurrences like the MBS, the De Gerlache Seamounts or the Hikurangi
Seamounts which are situated on top of Hikurangi Plateau off New
Zealand. An important difference between the seamounts and the continental alkaline provinces is that the majority of seamount provinces
formed on relatively young oceanic crust. While HIMU signatures can
be found in old continental terranes, HIMU-type volcanism in the
oceans either requires rise of HIMU material from depth or some sort
of refertilization of the upper mantle, especially when required shortly
after ocean crust formation. No doubt, small-scale heterogeneities
exist in the upper mantle away from mantle plumes as is evident
from small off-axis seamounts that often have more enriched element
and isotopic signatures than associated MORB (e.g., Brandl et al., 2012
and references therein). It seems, however, unlikely that such smallscale heterogeneities are present shortly after formation of the ocean
crust to an extent that can explain the c. 1000–8000 km3 of enriched
melt required to form individual MBS (see Table 1 for volume estimates).
In other words, even if Raleigh Taylor instabilities affected the Gondwana
margin it seems unlikely that upwelling of regular Pacific upper mantle
that underwent high degrees of melting shortly before can serve as the
source of the HIMU-type compositions without refertilization.
Alternatively, the superplume beneath the SW-Pacific could have
supplied a dense swarm of widely distributed and contemporaneously
active secondary plumes causing diffuse alkaline volcanism (Suetsugu
et al., 2009). Since it is in principle possible that secondary plumelets
or blobs are continuously rising from the SW Pacific superswell (presumed to have stalled at the 660 km transition zone; Courtillot et al.,
2003) they may also serve as the cause of volcanism forming the MBS
and De Gerlache Seamounts. The age–distance relationship between
MBS and the much farther north located Pacific Superswell is, however,
unclear. Alternatively, Timm et al. (2010 and references therein) identify
a low velocity anomaly extending from Chatham Rise off New Zealand to
western Antarctica in at 600–1500 km depth and suggest that this could
be the HIMU source polluting the upper mantle in this area since Cretaceous. Still it appears accidental that only the Marie Byrd Land margin
was hit by a short-lived swarm of plumelets and no other oceanic region
above this low velocity zone. Therefore we explore an alternative scenario for the oceanic seamount provinces off Marie Byrd Land based
on reactivation of (HIMU) material, added to the base of continental
lithosphere by plume activity during the pre-rifting stage of Marie
Byrd Land/Zealandia.
On a regional scale, the MBS and Belgica Seamount data overlap
with the data field of the Hikurangi Seamounts (Hoernle et al.,
2010) in most isotope correlation diagrams (Figs. 10–12). A similar
HIMU signature of Cretaceous rocks is also found at the Mandamus
complex, the Lookout Volcanics in southern New Zealand, and the
Chatham Islands (Weaver and Pankhurst, 1991; Tappenden, 2003;
Panter et al., 2006; McCoy-West et al., 2010). During the Cretaceous
these localities were assembled adjacent to Marie Byrd Land. It has
been proposed that a HIMU-type plume or plume head may have
caused breakup of the Gondwana margin in this region (e.g., Weaver
et al., 1994; Hart et al., 1997; Storey et al., 1999; Hoernle et al., 2010).
This plume event may have also influenced the source characteristics
of the Hikurangi Seamounts (Hoernle et al., 2010) and may have been
accompanied by large scale underplating of the Zealandia continental
lithosphere by HIMU material (e.g. Weaver et al., 1994; Hart et al.,
1997; Panter et al., 2000) (Fig. 13). During the mid Cretaceous the
plume head expanded and thus forced rifting and the breakup of Gondwana as it impacted at the base of the continental lithosphere (Weaver
et al., 1994). We note, however, that in contrast to other continental
breakup related mantle plumes such as the Tristan-Gough in the
1675
South-Atlantic (and related Paraná and Entendeka continental flood basalts), a flood basalt event is absent on Zealandia and West Antarctica,
possibly reflecting the convergent margin setting and associated thick
continental lithosphere along the Gondwana margin. Together with
the observation that the Cretaceous HIMU volcanism occurred only locally and was of relatively low volume, it seems likely that unmelted
HIMU-mantle got attached at the base the Gondwana lithosphere,
which underwent extension and rifting during that period. The proposed large-scale underplating of HIMU material beneath East Gondwana is consistent with the HIMU signature of many Cenozoic continental
volcanics from West Antarctica (e.g., Hobbs Coast, Marie Byrd Land Volcanic Province, and WARS; cf. Figs. 10 and 11). Accordingly, many authors relate the Cenozoic HIMU similarities in West Antarctica to the
reactivation of HIMU material, added to the base of the continental lithosphere during the earliest pre-rifting stage of the Marie Byrd Land
through plume activity (e.g., Weaver et al., 1994; Rocholl et al., 1995;
Hart et al., 1997; Panter et al., 2000). Alternatively Nardini et al. (2009
and references therein) call upon a late Cretaceous metasomatic event
that caused variable elevation of U/Pb ratios in the sub-lithospheric mantle to an extend that explains the high 206Pb/204Pb of b 20 Ma WARS volcanics and generation of their HIMU isotopic source signatures through
radiogenic ingrowth over extremely short time scales. The regional context, however, requires the presence of a HIMU component that is already
present in the Cretaceous, so that the metasomatic model of Nardini et al.
(2009) for the formation of HIMU appears less likely.
Notably, the field for continental volcanic rocks of West Antarctica
overlaps the data of the oceanic seamount provinces (Hikurangi
Seamounts, MBS, De Gerlache) (Figs. 10 and 11), which have been formed
close to the East Gondwana and West Antarctic margin, respectively. The
samples also fall within the range of Cretaceous volcanic rocks of southern
New Zealand, suggesting that all the above-mentioned volcanic suites
originate from a similar HIMU source. This material may therefore also
represent reactivation of fossil Cretaceous plume material that was originally attached to the base of the continental lithosphere during Marie
Byrd Land/Zealandia break up. In contrast to the above mentioned onshore occurrences of Cenozoic HIMU volcanism, an additional transport
mechanism and mode of reactivation is required to explain the marine
equivalents of HIMU volcanism, because this material needs first of all
be transferred into the oceanic mantle beneath the newly formed
ocean basins of the Amundsen/Bellingshausen Sea followed by decompression melting (see Section 7.4 for details).
Admittedly, the arguments for an initial upwelling of plume-like
material and storage at the base of the Gondwana lithosphere are
solely based on geochemistry, which points to a HIMU like mantle.
Such a source is unlikely to develop in situ in a mantle region affected
by long-term subduction zone volcanism and small scale convection
cells operating within the mantle wedge both leading to continuous
depletion and replenishment of the arc mantle. On the other hand,
upwelling of refertilized sub-continental lithospheric mantle (SCLM),
isolated from mantle circulation for several billion years, can lead to
the formation of EM type melts (e.g., Rudnick, 1995; Griffin et al.,
2009; Hoernle et al., 2011; Soager et al., 2013). Ancient SCLM, however,
features low 206Pb/204Pb and 143Nd/144Nd along with high 207Pb/204Pb
and 87Sr/86Sr ratios, reflecting an ancient source that evolved with low
U/Pb, Sm/Nd but high Rb/Sr (see Tang et al., 2013 for a recent review).
Mantle regions that underwent such a fractionation and/or metasomatic
event early in the earth's history are commonly thought to be involved in
the formation of the early continental crust, having resided thereafter in
the roots of stable Achaean cratons. In conclusion, SCLM seems to be a
very unlikely candidate as source of the Cretaceous HIMU-type intraplate
volcanism due the conflicting isotopic composition of SCLM (EM-like)
and the long-term subduction zone setting of this area. Therefore, our
preferred model for the origin of the HIMU component in the MBS and
De Gerlache lavas is reactivation of fossil Cretaceous plume material,
which was attached and stored at the base of the West Antarctic continental lithosphere during East Gondwana breakup.
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A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
7.4. Model for the formation of the Marie Byrd Seamounts
In the case of the West Antarctic volcanoes, underplated HIMU material may have been reactivated and caused to upwell during the WARS
extension (e.g., Hart et al., 1997). For the formation of the c. 99 to 67 Ma
Hikurangi Seamounts, Hoernle et al. (2010) propose the rise of
HIMU-type material directly beneath the Hikurangi Plateau — a
~118 Ma oceanic LIP (Hoernle et al., 2010) that formed in connection
with the Manihiki (Timm et al., 2011) and possibly the Ontong Java Plateaus (Taylor, 2006), through deflection of rising plume material beneath Zealandia by the subducting plate towards the Hikurangi
Plateau, which was about to collide with the Zealandia margin at that
time (Fig. 13a + b). For the MBS and De Gerlache Seamounts, however,
a mechanism is required that enables lateral transport of the earlier
emplaced HIMU material under Marie Byrd Land beneath the newly
formed bordering oceanic lithosphere.
When the new oceanic crust of the Amundsen Sea formed,
Zealandia (including the Hikurangi Plateau) rifted away from Marie
Byrd Land in a northward direction (Fig. 13c), whereas the West Antarctic continental margin remained more or less fixed and developed
as a relatively stable passive margin thereafter (e.g., Eagles et al.,
2004a; Wobbe et al., 2012). Mutter et al. (1988) proposed a transition
zone directly at the edge of thicker to thinner lithosphere where
small convective flow is focused. In case of the MBS and De Gerlache
Seamounts, the transition zone lies at the edge of the Antarctic continental lithosphere and the beginning of the adjacent oceanic crust. Several
mechanisms such as edge-driven convection (EDC), small-scale convection (SSC) or shear-driven upwelling (SDU) have been suggested to explain edge-driven buoyant flow between young, thin and old, thicker
lithosphere (e.g., King and Anderson, 1995, 1998; King and Ritsema,
2000; Huang et al., 2003; Dumoulin et al., 2008; Conrad and Behn,
2010 and references therein). For example, (super-) continents may
effectively insulate the upper mantle, leading to a buildup of heat
(Anderson, 1994; Lowman and Jarvis, 1995, 1996; Gurnis et al., 1998).
These lateral temperature differences between the warm mantle beneath the continental lithosphere and normal upper mantle can drive
an upper mantle convective flow pattern that leads to upwelling beneath the continent–ocean transition zone (Fig. 13d), the so-called
“continental-insulation flow” (e.g., King and Anderson, 1995, 1998).
From numerical modeling, King and Anderson (1998) suggest that lateral variations in temperature of at least 30 °C are required for continental
insulation flow to significantly modify or even shut off the normal,
downwelling EDC flow. Higher temperature anomalies (150–200 °C)
would drive major upper mantle convection cells. In case of the Cretaceous East Gondwana lithosphere, the impact of the hot plume head
may have caused additional heating of the mantle beneath the continental lithosphere and therefore reinforced the lateral variations in mantle
temperature and consequently mantle convection. Notably, the pattern
of flow resulting from continental insulation is opposite to that of normal EDC flow (King and Anderson, 1995, 1998). At the initial stages of
rifting of a continent, upwelling should occur as warm mantle from beneath the continent that occupies the space created by spreading between the continental masses. At the Late Cretaceous Marie Byrd Land
margin, this process would transfer mantle material directly from beneath the continent into the upper mantle under the adjacent oceanic
lithosphere on which the MBS started to form at that time (Fig. 13d).
Therefore we consider continental insulation flow as the most plausible
mechanism to bring the HIMU plume-like material previously attached
beneath Marie Byrd Land upwards beneath the adjacent oceanic lithosphere of the Bellingshausen/Antarctic Plate.
As the HIMU material was transported upwards beneath the
newly formed oceanic lithosphere from beneath the thick Antarctica
continental crust, the material will melt by decompression. The volcanism forming the De Gerlache Seamounts at ~ 22 Ma and the Pleistocene activity of Peter I Island, on the other hand, was most likely
related to the De Gerlache Gravity Anomaly (Figs. 1 and 2), which
represents a zone of lithospheric weakness resulting from a presumed WARS activity in this region (Müller et al., 2007), where
pre-existing N–S striking faults allowed rise (and decompression
melting) of HIMU-type material brought up beneath the oceanic lithosphere by mantle convection. The formation of the MBS may therefore
have been triggered by a complex sequence of plate reorganization
events that affected the West Antarctic margin and the Bellingshausen
Plate in Late Cretaceous and Early Cenozoic (e.g., Eagles et al., 2004a;
Wobbe et al., 2012). Shortly before the Bellingshausen Plate became incorporated into the Antarctic Plate at 61 Ma (Eagles et al., 2004a,b;
Wobbe et al., 2012), a change in rotation of the Bellingshausen Plate
from counterclockwise to clockwise was accompanied by lithospheric
extension on its southern margin between 74 and 62 Ma (Wobbe
et al., 2012). Contemporaneously the MBS started to form in that area
(Fig. 2) (Fig. 13d), suggesting that lithospheric extension lead to upwelling of sub-lithospherically attached HIMU material and deep
reaching faults that allowed rise of the HIMU-type melts and formation
of large volcanic islands (Fig. 13d).
8. Conclusions
Our new morphological, geochronological, and geochemical data
for the MBS combined with additional data for the De Gerlache and
Peter I Island volcanic complexes (complementing previously published data) permit for the first time a comprehensive reconstruction
of the origin and evolution of Cenozoic intraplate volcanism in the
Amundsen Sea. The most important results are:
(1) Intraplate volcanism occurred during the entire Cenozoic at distinct time intervals in spatially confined areas in the Amundsen
Sea, excluding an origin of this volcanism by a single stationary
hotspot.
(2) The MBS and De Gerlache Seamount lavas show OIB signatures
and posses a distinct HIMU component in their magma source
similar to Late Cretaceous–Cenozoic volcanics of the Hikurangi
Seamounts off New Zealand, intraplate volcanic fields in New
Zealand, sub-Antarctic islands and the WARS, suggesting a common mantle source for these volcanic provinces.
(3) Peter I Island displays a strong EM affinity probably caused by
shallow mantle recycling of a continental fragment.
Consequently, the formation of the MBS and De Gerlache Seamounts
intraplate volcanism requires an alternative, non-hotspot scenario,
which takes distinct melting anomalies independent in space and time
and a non-hotspot related HIMU source into account.
Placing the morphological, geochronological, and geochemical
data in a regional plate tectonic context, we conclude that the most
plausible explanation for the HIMU-type intraplate volcanism in
the Amundsen Sea is reactivation of HIMU-material, added to the
base of the Antarctic lithosphere by a Late Cretaceous plume event.
Major tectonic events, namely the separation of Zealandia from
Antarctica during the final stage of the Gondwana break-up and
subsequent formation of ocean crust give way for transport of the
sub-lithospheric HIMU material beneath the Amundsen Sea oceanic
crust by continental insulation flow. Extension caused by plate tectonic reorganization (MBS) and/or lithospheric weakening underneath
the De Gerlache Gravity Anomaly (De Gerlache, Peter I Island) allow rise
and adiabatic melting of the HIMU material resulting in the formation of these volcanic edifices. Reactivation of the MBS magmatism
resulting in Pliocene low volume volcanism and the Pleistocene
formation of Peter I Island documents ongoing magmatism in the
Amundsen Sea.
The new model for the Amundsen Sea volcanism presented here
adds to case examples for non-hotspot intraplate volcanism and provides additional evidence that HIMU-type intraplate volcanism is not
necessarily a direct consequence of an actively upwelling, stationary
mantle plume or hotspot.
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
Supplementary data to this article can be found online at http://
dx.doi.org/10.1016/j.gr.2013.06.013.
Acknowledgments
We are grateful to Captain Pahl, the crew, and shipboard scientific
party for their excellent support during RV Polarstern cruise ANT-XXIII/
4. R. Gersonde (AWI) kindly provided the dredge samples from Belgica
Seamount. D. Rau, S. Hauff, J. Sticklus (GEOMAR) and H. Anders
(Uni-Bremen) are thanked for technical assistance during lab work
and S. Gauger for help with processing of the bathymetric data. Discussions with Maxim Portnyagin, Jan Grobys, Graeme Eagles, and
Christian Timm significantly helped to develop this paper. Furthermore,
we are grateful for the constructive reviews of John Gamble and
Tsuyoshi Komiya that helped to improve an earlier version of the manuscript. We thank Inna Yu Safonova for editorial handling and useful
comments that helped to emphasize the importance of seamount formation. The German Research Foundation (DFG; Grants HO1833/15-1
to -3 to KH and FH) funded this research.
References
Anderson, D.L., 1994. Superplumes or supercontinents? Geology 22, 39–42. http://
dx.doi.org/10.1130/0091-7613(1994)022b0039:SOSN2.3.CO;2.
Anderson, D.L., 2000. The thermal state of the upper mantle; no role for mantle plumes.
Geophysical Research Letters 27 (22), 3623–3626. http://dx.doi.org/10.1029/
2000GL011533.
Baker, I.A., Gamble, J.A., Graham, I.J., 1994. The age, geology, and geochemistry of the
Tapuaenuku Igneous Complex, Marlborough, New Zealand. New Zealand Journal of Geology and Geophysics 37, 249–268. http://dx.doi.org/10.1080/00288306.1994.9514620.
Baksi, A.K., 2007. A quantitative tool for detecting alteration in undisturbed rocks and
minerals — I: water, chemical weathering, and atmospheric argon. Special Paper
of the Geological Society of America 430 (1197), 285–303. http://dx.doi.org/
10.1130/2007.2430(16).
Batiza, R., Niu, Y., Zayac, W.C., 1990. Chemistry of seamounts near the East Pacific Rise:
implications for the geometry of subaxial mantle flow. Geology 18, 1122–1125
(doi:1122-112510.1130/0091-7613(1990)018 b 1122:COSNTE N 2.3.CO;2).
Boger, S.D., 2011. Antarctica — before and after Gondwana. Gondwana Research 19 (2),
335–371. http://dx.doi.org/10.1016/j.gr.2010.09.003.
Bradshaw, J.D., 1989. Cretaceous geotectonic patterns in the New Zealand region. Tectonics 8, 803–820. http://dx.doi.org/10.1029/TC008i004p00803.
Brandl, P.A., Beier, C., Regelous, M., Abouchami, W., Haase, K.M., Garbe-Schönberg, D.,
Galer, S.J.G., 2012. Volcanism on the flanks of the East Pacific Rise: quantitative
constraints on mantle heterogeneity and melting processes. Chemical Geology
298–299, 41–56. http://dx.doi.org/10.1016/j.chemgeo.2011.12.015.
Broch, O.A., 1927. Gesteine von der Peter I.-lnsel, West Antarktis. Avhandlinger/Det
Norske Videnskaps-Akademi, I, Matematisk-Naturvidenskapelig Oslo KL 9, 1–41.
Buchs, D.M., Arculus, R.J., Baumgartner, P.O., Ulianov, A., 2011. Oceanic intraplate volcanoes exposed: example from seamounts accreted in Panama. Geology 39, 335–338.
http://dx.doi.org/10.1130/G31703.1.
Conrad, C.P., Behn, M.D., 2010. Constraints on lithosphere net rotation and asthenospheric
viscosity from global mantle flow models and seismic anisotropy. Geochemistry, Geophysics, Geosystems 11, Q05W05. http://dx.doi.org/10.1029/2009GC002970.
Courtillot, V., Davaille, A., Besse, J., Stock, J., 2003. Three distinct types of hotspots in the
Earth's mantle. Earth and Planetary Science Letters 205, 295–308. http://dx.doi.org/
10.1016/S0012-821X(02)01048-8.
Davy, B.W., Hoernle, K., Werner, R., 2008. Hikurangi Plateau: crustal structure, rifted
formation, and Gondwana subduction history. Geochemistry, Geophysics, Geosystems
9, Q07004. http://dx.doi.org/10.1029/2007GC001855.
Doubrovine, P.V., Steinberger, B., Torsvik, T.H., 2012. Absolute plate motions in a reference
frame defined by moving hot spots in the Pacific, Atlantic, and Indian oceans. Journal
of Geophysical Research 117, B09101. http://dx.doi.org/10.1029/2011JB009072.
Dumoulin, C., Choblet, G., Doin, M.P., 2008. Convective interactions between oceanic
lithosphere and asthenosphere: influence of a transform fault. Earth and Planetary
Science Letters 274, 301–309. http://dx.doi.org/10.1016/j.epsl.2008.07.017.
Eagles, G., Gohl, K., Larter, R., 2004a. High-resolution animated tectonic reconstruction
of the South Pacific and West Antarctic Margin. Geochemistry, Geophysics,
Geosystems 5, Q07002. http://dx.doi.org/10.1029/2003GC000657.
Eagles, G., Gohl, K., Larter, R., 2004b. Life of the Bellingshausen Plate. Geophysical Research Letters 31, L07603. http://dx.doi.org/10.1029/2003GL019127.
Eagles, G., Larter, R., Gohl, K., Vaughan, A.P.M., 2009. West Antarctic Rift System in the
Antarctic Peninsula. Geophysical Research Letters 36, L21305. http://dx.doi.org/
10.1029/2009GL040721.
Feldberg, M.J., 1997. A Geophysical Study of Seamount E, Bellingshausen Sea, Antarctica. Diploma Degree of Bachelor of Arts Wesleyan University, USA.
Finn, C.A., Müller, R.D., Panter, K.S., 2005. A Cenozoic diffuse alkaline magmatic province in the SW Pacific without rift or plume origin. Geochemistry, Geophysics,
Geosystems 6, Q02005. http://dx.doi.org/10.1029/2004GC000723.
1677
Fisher, A.T., Davis, E.E., Hutnak, M., Spiess, V., Zühlsdorff, L., Cherkaoui, A., Christiansen,
L., Edwards, K., Macdonald, R., Villinger, H., Mottl, M.J., Wheat, C.G., Becker, K., 2003.
Hydrothermal recharge and discharge across 50 km guided by seamounts on a
young ridge flank. Nature 421, 618–621. http://dx.doi.org/10.1038/nature01352.
Foulger, G.R., Natland, J.H., 2003. Is “hotspot” volcanism a consequence of plate tectonics? Science 300, 921–922. http://dx.doi.org/10.1126/science.1083376.
Frey, F.A., Wise, W.S., Garcia, M.O., West, H., Kwon, S.-T., Kennedy, A., 1990. Evolution of
Mauna Kea Volcano, Hawaii: petrologic and geochemical constraints on postshield
volcanism. Journal of Geophysical Research 95 (B2), 1271–1300. http://dx.doi.org/
10.1029/JB095iB02p01271.
Garcia, M.O., Jorgenson, B.A., Mahoney, J.J., Ito, E., Irving, A.J., 1993. An evaluation of
temporal geochemical evolution of Loihi Summit Lavas: results from Alvin submersible dives. Journal of Geophysical Research 98 (B1), 537–550. http://dx.doi.org/
10.1029/92JB01707.
Geldmacher, J., Hanan, B.B., Blichert-Toft, J., Harpp, K., Hoernle, K., Hauff, F., Werner, R.,
und Kerr, A., 2003. Hf isotopic variations in volcanic rocks from the Caribbean Large
Igneous Province and Galápagos hotspot tracks. Geochemistry, Geophysics,
Geosystems 422 (7). http://dx.doi.org/10.1029/2002GC000477.
Geldmacher, J., Hoernle, K., van den Bogaard, P., Duggen, S., Werner, R., 2005. New
40
Ar/39Ar age and geochemical data from seamounts in the Canary and Madeira
volcanic provinces: support for the mantle plume hypothesis. Earth and Planetary
Science Letters 237, 85–101. http://dx.doi.org/10.1016/j.epsl.2005.04.037.
Geldmacher, J., Hoernle, K., van den Bogaard, P., Hauff, F., Klügel, A., 2008. Age and geochemistry of the Central American forearc basement (DSDP Leg 67 and 84): insights into Mesozoic arc volcanism and seamount accretion on the fringe of the
Caribbean LIP. Journal of Petrology 49, 1781–1815. http://dx.doi.org/10.1093/petrology/egn046.
Gohl, K., 2007. The expedition ANTARKTIS-XXIII/4 of the research vessel Polarstern in
2006. Berichte zur Polar- und Meeresforschung (Reports on Polar and Marine Research), no. 557. Alfred Wegener Institute for Polar and Marine Research, Bremerhaven (166 pp. http://epic.awi.de/26756/).
Gohl, K., Nitsche, F.O., Miller, H., 1997a. Seismic and gravity data reveal Tertiary
interplate subduction in the Bellingshausen Sea, Southeast Pacific. Geology 25,
371–374. http://dx.doi.org/10.1130/0091-7613(1997)025b0371:SAGDRTN2.3.CO;2.
Gohl, K., Nitsche, F., Vanneste, K., Miller, H., Fechner, N., Oszko, L., Hübscher, C., Weigelt,
E., Lambrecht, A., 1997b. Tectonic and sedimentary architecture of the Bellingshausen
and Amundsen Sea Basins, SE Pacific, by seismic profiling. In: Ricci, C.A. (Ed.), The Antarctic Region: Geological Evolution and Processes. Terra Antartica Publication, Siena,
pp. 719–723.
Gohl, K., Denk, A., Wobbe, F., Eagles, G., 2013. Deciphering tectonic phases of the
Amundsen Sea Embayment shelf, West Antarctica, from a magnetic anomaly
grid. Tectonophysics 585, 113–123. http://dx.doi.org/10.1016/j.tecto.2012.06.036.
Griffin, W.L., O'Reilly, S.Y., Afonso, J.C., Begg, G.C., 2009. The composition and evolution
of lithospheric mantle: a re-evaluation and its tectonic implications. Journal of Petrology 50, 1185–1204. http://dx.doi.org/10.1093/petrology/egn033.
Gurnis, M., Mueller, R.D., Moresi, L., 1998. Dynamics of Cretaceous vertical motion of
Australia and the Australian–Antarctic discordance. Science 279, 1499–1504.
http://dx.doi.org/10.1126/science.279.5356.1499.
Hagedorn, B., Gersonde, R., Gohl, K., Hubberten, H.-W., 2007. Petrology, geochemistry
and K–Ar age constraints of the eastern De Gerlache Seamount alkaline basalts
(Bellingshausen Sea, Southeast Pacific). Polarforschung 76 (3), 87–94 (http://
epic.28876.d001).
Harris, R.N., Fisher, A.T., Chapman, D.S., 2004. Fluid flow through seamounts and implications
for global mass fluxes. Geology 32, 725–728. http://dx.doi.org/10.1130/G20387.1.
Hart, S.R., Hauri, E.H., Oschmann, L.A., Whitehead, J.A., 1992. Mantle plumes and entrainment: isotopic evidence. Science 256, 517–520. http://dx.doi.org/10.1126/
science.256.5056.517.
Hart, S.R., Blusztajn, J., Craddock, C., 1995. Cenozoic volcanism in Antarctica: Jones
Mountains and Peter I Island. Geochimica et Cosmochimica Acta 59, 3379–3388.
http://dx.doi.org/10.1016/0016-7037(95)00212-I.
Hart, S.R., Blusztajn, J., LeMasurier, W.E., Rex, D.C., 1997. Hobbs Coast Cenozoic volcanism, implications for the West Antarctic Rift System. Chemical Geology 139,
223–248. http://dx.doi.org/10.1016/S0009-2541(97)00037-5.
Hauri, E.H., Whitehead, J.A., Hart, S.A., 1994. Fluid dynamic and geochemical aspects of
entrainment in mantle plumes. Journal of Geophysical Research 99 (B12),
24275–24300. http://dx.doi.org/10.1029/94JB01257.
Hein, J.R., Conrad, T.A., Staudigel, H., 2010. Seamount mineral deposits: a source of rare
metals for high-technology industries. Oceanography 23, 184–189. http://
dx.doi.org/10.5670/oceanog.2010.70.
Heinemann, J., Stock, J., Clayton, R., Hafner, K., Cande, S., Raymond, C., 1999. Constraints
on the proposed Marie Byrd Land–Bellingshausen Plate boundary from seismic reflection data. Journal of Geophysical Research 104 (B11), 25321–25330. http://
dx.doi.org/10.1029/1998JB900079.
Hirschmann, M.M., Stolper, E.M., 1996. A possible role for garnet pyroxenite in the origin of the “garnet signature” in MORB. Contributions to Mineralogy and Petrology
124, 185–208. http://dx.doi.org/10.1007/s004100050184.
Hoernle, K., van den Bogaard, P., Werner, R., Lissina, B., Hauff, F., Alvarado, G., GarbeSchönberg, D., 2002. Missing history (16–71 Ma) of the Galápagos hotspot: implications
for the tectonic and biological evolution of the Americas. Geology 30, 795–798. http://
dx.doi.org/10.1130/0091-7613(2002)030b0795:mhmotgN2.0.co;2.
Hoernle, K., Hauff, F., Werner, R., Mortimer, N., 2004. New insights into the origin and
evolution of the Hikurangi Oceanic Plateau (Southwest Pacific) from multi-beam
mapping and sampling. Eos, Transactions of the American Geophysical Union 85
(41), 401–408. http://dx.doi.org/10.1029/2004EO410001.
Hoernle, K., White, J.D.L., van den Bogaard, P., Hauff, F., Coombs, D.S., Werner, R., Timm, C.,
Garbe-Schoenberg, D., Reay, A., Cooper, A.F., 2006. Cenozoic intraplate volcanism on
1678
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
New Zealand: upwelling induced by lithospheric removal. Earth and Planetary Science Letters 248, 350–367. http://dx.doi.org/10.1016/j.epsl.2006.06.001.
Hoernle, K., Hauff, F., van den Bogaard, P., Werner, R., Mortimer, N., Geldmacher, J.,
Garbe-Schoenberg, D., Davy, B., 2010. Age and geochemistry of volcanic rocks
from the Hikurangi and Manihiki Oceanic Plateaus. Geochimica et Cosmochimica
Acta 74 (24), 7196–7219. http://dx.doi.org/10.1016/j.gca.2010.09.030.
Hoernle, K., Hauff, F., Werner, R., van den Bogaard, P., Gibbons, A.D., Conrad, S., Müller, R.D.,
2011. Origin of Indian Ocean Seamount Province by shallow recycling of continental
lithosphere. Nature Geoscience 4, 883–887. http://dx.doi.org/10.1038/ngeo1331.
Hofmann, A.W., 1988. Chemical differentiation of the Earth: the relationship between
mantle, continental and oceanic crust. Earth and Planetary Science Letters 90,
297–314. http://dx.doi.org/10.1016/0012-821X(88)90132-X.
Hofmann, A.W., 2003. Sampling mantle heterogeneity through oceanic basalts: isotopes and trace elements. In: Carlson, R.W. (Ed.), The Mantle and Core. Elsevier,
Amsterdam, pp. 61–101. http://dx.doi.org/10.1016/B0-08-043751-6/02123-X.
Hofmann, A.W., White, W.M., 1982. Mantle plumes from ancient oceanic crust. Earth and
Planetary Science Letters 57, 421–436. http://dx.doi.org/10.1016/0012-821X(82)
90161-3.
Hofmann, A.W., Jochum, K.-P., Seufert, M., White, W.M., 1986. Nb and Pb in oceanic basalts: new constraints on mantle evolution. Earth and Planetary Science Letters 79,
33–45. http://dx.doi.org/10.1016/0012-821X(86)90038-5.
Hole, M.J., LeMasurier, W.E., 1994. Tectonic controls on the geochemical composition of
Cenozoic, mafic alkaline volcanic rocks from West Antarctica. Contributions to
Mineralogy and Petrology 117, 187–202. http://dx.doi.org/10.1007/BF00286842.
Huang, J., Zhong, S., van Hunen, J., 2003. Controls on sub-lithospheric small-scale convection. Journal of Geophysical Research 108 (B8), 2405. http://dx.doi.org/10.1029/
2003JB002456.
Hutnak, M., Fisher, A.T., Harris, R., Stein, C., Wang, K., Spinelli, G., Schindler, M., Villinger, H.,
Silver, E., 2008. Large heat and fluid fluxes driven through mid-plate outcrops on
ocean crust. Nature Geoscience 1, 611–614. http://dx.doi.org/10.1038/ngeo264.
Irvine, T.N., Baragar, W.R.A., 1971. A guide to the chemical classification of the common
volcanic rocks. Canadian Journal of Earth Sciences 8, 523–548. http://dx.doi.org/
10.1139/e71-055.
King, S.D., Anderson, D.L., 1995. An alternative mechanism to flood basalt formation.
Earth and Planetary Science Letters 136, 269–279. http://dx.doi.org/10.1016/
0012-821X(95)00205-Q.
King, S.D., Anderson, D.L., 1998. Edge-driven convection. Earth and Planetary Science
Letters 160, 289–296. http://dx.doi.org/10.1016/S0012-821X(98)00089-2.
King, S.D., Ritsema, J., 2000. African hotspot volcanism: small-scale convection in the
upper mantle beneath cratons. Science 290, 1137–1140. http://dx.doi.org/10.1126/
science.290.5494.1137.
Klügel, A., Hansteen, T.H., van den Bogaard, P., Strauss, H., Hauff, F., 2011. Holocene
fluid venting at an extinct Cretaceous seamount, Canary Archipelago. Geology 39,
855–858. http://dx.doi.org/10.1130/G32006.1.
Koppers, A.A.P., Yamazaki, T., Geldmacher, J., Gee, J.S., Pressling, N., IODP Expedition
330 Scientific Party, 2012. Limited latitudinal mantle plume motion for the Louisville hotspot. Nature Geoscience 5, 911–917. http://dx.doi.org/10.1038/ngeo1638.
Larter, R.D., Cunningham, A.P., Barker, P.F., Gohl, K., Nitsche, F.O., 2002. Tectonic evolution of
the Pacific margin of Antarctica — 1. Late Cretaceous tectonic reconstructions. Journal of
Geophysical Research 107 (B12), 2345. http://dx.doi.org/10.1029/2000JB000052.
LeMasurier, W.E., Thomson, J.W., Baker, P., Kyle, P., Rowley, P., Smellie, J., Verwoerd, W.
(Eds.), 1990. Volcanoes of the Antarctic Plate and Southern Oceans. Antarctic Research Series, 48. AGU, Washington, D.C., p. 487. http://dx.doi.org/10.1029/AR048.
Lowman, J.P., Jarvis, G.T., 1995. Mantle convection models of continental collision and
breakup incorporating finite thickness plates. Physics of the Earth and Planetary
Interiors 88, 53–68. http://dx.doi.org/10.1016/0031-9201(94)05076-A.
Lowman, J.P., Jarvis, G.T., 1996. Continental collisions in wide aspect ratio and high Rayleigh number two-dimensional mantle convection models. Journal of Geophysical
Research 101 (B11), 25485–25497. http://dx.doi.org/10.1029/96JB02568.
McAdoo, D.C., Laxon, S., 1997. Antarctic tectonics: constraints from an ERS-1 satellite marine
gravity field. Science 276, 556–560. http://dx.doi.org/10.1126/science.276.5312.556.
McCoy-West, A.J., Baker, J.A., Faure, K., Wysoczanski, R., 2010. Petrogenesis and origins
of mid-Cretaceous continental intraplate volcanism in Marlborough, New Zealand:
implications for the long-lived HIMU magmatic mega-province of the SW Pacific.
Journal of Petrology 51, 2003–2045. http://dx.doi.org/10.1093/petrology/egq046.
McDonough, W.F., Sun, S.-S., 1995. The composition of the earth. Chemical Geology
120, 223–253. http://dx.doi.org/10.1016/0009-2541(94)00140-4.
McMurtry, G.M., Fryer, G.J., Tappin, D.R., Wilkinson, I.P., Williams, M., Fietzke, J., GarbeSchönberg, D., Watts, P., 2004. Megatsunami deposits on Kohala Volcano, Hawaii, from
flank collapse of Mauna Loa. Geology 32, 741–744. http://dx.doi.org/10.1130/G20642.1.
Miller, H., Grobe, H., 1996. The expedition ANTARKTIS-XI/3 of RV ‘Polarstern’ in 1994.
Berichte zur Polarforschung, no. 188 (http://epic.10189.d001).
Montelli, R., Nolet, G., Dahlen, F.A., Masters, G., 2006. A catalogue of deep mantle
plumes: new results from finite-frequency tomography. Geochemistry, Geophysics, Geosystems 7, Q11007. http://dx.doi.org/10.1029/2006GC001248.
Morgan, W.J., 1971. Convection plumes in the lower mantle. Nature 230, 42–43. http://
dx.doi.org/10.1038/230042a0.
Müller, R.D., Gaina, C., Tikku, A., Mihut, D., Cande, S.C., Stock, J.M., 2000. Mesozoic/Cenozoic tectonic events around Australia. Geophysical Monograph 121, 161–188.
http://dx.doi.org/10.1029/GM121p0161.
Müller, R.D., Gohl, K., Cande, S.C., Goncharov, A., Golynsky, A.V., 2007. Eocene to Miocene geometry of the West Antarctic Rift System. Australian Journal of Earth Sciences 54, 1033–1045. http://dx.doi.org/10.1080/08120090701615691.
Mutter, J.C., Buck, W.R., Zehnder, C.M., 1988. Convective partial melting 1. A model for
the formation of thick basaltic sequences during the initiation of spreading. Journal of
Geophysical Research 93 (B2), 1031–1048. http://dx.doi.org/10.1029/JB093iB02p01031.
Nardini, I., Armienti, P., Rocchi, S., Dallai, L., Harrison, D., 2009. Sr–Nd–Pb–He–O isotope
and geochemical constraints on the genesis of Cenozoic magmas from the West
Antarctic Rift. Journal of Petrology 50 (7), 1359–1375. http://dx.doi.org/10.1093/
petrology/egn082.
Natland, J.H., Winterer, E.L., 2005. Fissure control on volcanic action in the Pacific. In:
Foulger, G.R., Natland, J.H., Presnall, D.C., Anderson, D.L. (Eds.), Plumes, Plates
and Paradigms. Geological Society of America, Boulder CO, pp. 687–710. http://
dx.doi.org/10.1130/0-8137-2388-4.687.
Panter, K.S., Kyle, P.R., Smellie, J.L., 1997. Petrogenesis of a phonolite–trachyte succession at Mount Sidley, Marie Byrd Land, Antarctica. Journal of Petrology 38 (9),
1225–1253. http://dx.doi.org/10.1093/petroj/38.9.1225.
Panter, K.S., Hart, S.R., Kyle, P., Blusztanjn, J., Wilch, T., 2000. Geochemistry of Late Cenozoic basalts from the Crary Mountains: characterization of mantle sources in
Marie Byrd Land, Antarctica. Chemical Geology 165, 215–241. http://dx.doi.org/
10.1016/S0009-2541(99)00171-0.
Panter, K.S., Blusztanjn, J., Hart, S.R., Kyle, P.R., Esser, R., McIntash, W.C., 2006. The origin of HIMU in the SW Pacific: evidence from intraplate volcanism in southern
New Zealand and Subantarctic islands. Journal of Petrology 47, 1673–1704.
http://dx.doi.org/10.1093/petrology/egl024.
Portnyagin, M., Savelyev, D., Hoernle, K., Hauff, F., Garbe-Schönberg, D., 2008. MidCretaceous Hawaiian tholeiites preserved in Kamchatka. Geology 36, 903–906.
http://dx.doi.org/10.1130/g25171a.1.
Prestvik, T., Duncan, R.A., 1991. The geology and age of Peter I Øy, Antarctica. Polar Research 9, 89–98. http://dx.doi.org/10.1111/j.1751-8369.1991.tb00404.x.
Prestvik, T., Barnes, C.G., Sundvoll, B., Duncan, R.A., 1990. Petrology of Peter I Øy (Peter I
Island), West Antarctica. Journal of Volcanology and Geothermal Research 44,
315–338. http://dx.doi.org/10.1016/0377-0273(90)90025-B.
Rocchi, S., Armienti, P., D'Orazio, M., Tonarini, S., Wijbrans, J., Di Vincenzo, G., 2002a.
Cenozoic magmatism in the western Ross Embayment: role of mantle plume versus plate dynamics in the development of the West Antarctic Rift System. Journal
of Geophysical Research 107 (B9), 2195. http://dx.doi.org/10.1029/2001JB000515.
Rocchi, S., LeMasurier, W.E., Di Vincenzo, G., 2002b. Uplift and erosion history in
Marie Byrd Land as a key to possible mid-Cenozoic plate motion between East
and West Antarctica. Geological Society of America Abstracts with Programs 34
(6), 238.
Rocholl, A., Stein, M., Molzahn, M., Hart, S.R., Wörner, G., 1995. Geochemical evolution
of rift magmas by progressive tapping of a stratified mantle source beneath the
Ross Sea Rift, Northern Victoria Land, Antarctica. Earth and Planetary Science Letters 131, 207–224. http://dx.doi.org/10.1016/0012-821X(95)00024-7.
Rudnick, R.L., 1995. Making continental crust. Nature 378, 571–578. http://dx.doi.org/
10.1038/378571a0.
Safonova, I.Y., 2009. Intraplate magmatism and oceanic plate stratigraphy of the PaleoAsian and Paleo-Pacific Oceans from 600 to 140 Ma. Ore Geology Reviews 35,
137–154. http://dx.doi.org/10.1016/j.oregeorev.2008.09.002.
Safonova, I.Y., Santosh, M., 2012. Accretionary complexes in the Asia–Pacific region:
tracing archives of ocean plate stratigraphy and tracking mantle plumes. Gondwana Research 25, 126–158.
Salters, V.J.M., Stracke, A., 2004. Composition of the depleted mantle. Geochemistry,
Geophysics, Geosystems 5, Q05B07. http://dx.doi.org/10.1029/2003GC000597.
Shank, T.M., 2010. Seamounts: deep-ocean laboratories of faunal connectivity, evolution, and endemism. Oceanography 23, 108–122. http://dx.doi.org/10.5670/
oceanog.2010.65.
Smith, W.H.F., Sandwell, D.T., 1997. Global sea floor topography from satellite altimetry
and ship depth soundings. Science 277, 1956–1962. http://dx.doi.org/10.1126/
science.277.5334.1956.
Soager, N., Holm, P.M., Llambias, E.J., 2013. Payenia volcanic province, southern Mendoza, Argentina: OIB mantle upwelling in a backarc environment. Chemical Geology
349–350, 36–53. http://dx.doi.org/10.1016/j.chemgeo.2013.04.007.
Stock, J.M., 1997. Geophysical secrets beneath Antarctic waters. Engineering Sciences
60 (3), 18–27.
Storey, B.C., Leat, P.T., Weaver, S.D., Pankhurst, R.J., Bradshaw, J.D., Kelley, S., 1999.
Mantle plumes and Antarctica–New Zealand rifting; evidence from MidCretaceous mafic dykes. Journal of the Geological Society 156, 659–671. http://
dx.doi.org/10.1144/gsjgs.156.4.0659.
Stracke, A., 2012. Earth's heterogeneous mantle: a product of convection-driven interaction between crust and mantle. Chemical Geology 330–331, 274–299. http://
dx.doi.org/10.1016/j.chemgeo.2012.08.007.
Suetsugu, D., Isse, T., Tanaka, S., Obayashi, M., Shiobara, H., Sugioka, H., Kanazawa, T.,
Fukao, Y., Barruol, G., Reymond, D., 2009. South Pacific mantle plumes imaged by
seismic observation on islands and seafloor. Geochemistry, Geophysics, Geosystems
10, Q11014. http://dx.doi.org/10.1029/2009GC002533.
Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematics of oceanic basalts:
implications for mantle composition and processes. In: Saunders, A.D., Norry, M.J.
(Eds.), Magmatism in the Ocean Basins. Geological Society Special Publications,
42, pp. 313–345. http://dx.doi.org/10.1144/GSL.SP.1989.042.01.19.
Sutherland, R., Spasojevic, S., Gurnis, M., 2010. Mantle upwelling after Gondwana subduction
death explains anomalous topography and subsidence history of eastern New Zealand
and West Antarctic. Geology 38, 155–158. http://dx.doi.org/10.1130/G30613.1.
Tang, Y.-J., Zhang, H.-F., Ying, J.-F., Su, B.-X., 2013. Widespread refertilization of cratonic
and circum-cratonic lithospheric mantle. Earth-Science Reviews 118, 45–68.
http://dx.doi.org/10.1016/j.earscirev.2013.01.004.
Tappenden, V.E., 2003. Magmatic Response to the Evolving New Zealand Margin of
Gondwana During the Mid–Late Cretaceous. (PhD thesis) University of Canterbury,
Christchurch, New Zealand.
Tarduno, J.A., Duncan, R.A., Scholl, D.W., Cottrell, R.D., Steinberger, B., Thordason, T.,
Kerr, B.C., Neal, C.R., Frey, F.A., Torii, M., Carvallo, C., 2003. The Emperor Seamounts:
A. Kipf et al. / Gondwana Research 25 (2014) 1660–1679
southward motion of the Hawaiian hotspot plume in earth's mantle. Science 301,
1064–1069. http://dx.doi.org/10.1126/science.1086442.
Taylor, B., 2006. The single largest oceanic plateau: Ontong Java–Manihiki–Hikurangi.
Earth and Planetary Science Letters 241, 372–380. http://dx.doi.org/10.1016/
j.epsl.2005.11.049.
Timm, C., Hoernle, K., Werner, R., Hauff, F., van den Bogaard, P., White, J., Mortimer, N.,
Garbe-Schoenberg, D., 2010. Temporal and geochemical evolution of the Cenozoic
intraplate volcanism of Zealandia. Earth-Science Reviews 98, 38–64. http://
dx.doi.org/10.1016/j.earscirev.2009.10.002.
Timm, C., Hoernle, K., Werner, R., Hauff, F., van den Bogaard, P., Michael, P., Coffin, M.,
Koppers, A., 2011. Age and geochemistry of the oceanic Manihiki Plateau, SW Pacific: new evidence for a plume origin. Earth and Planetary Science Letters 304 (1–2),
135–146. http://dx.doi.org/10.1016/j.epsl.2011.01.025.
Udintsev, G.B., Kurentsova, N.A., Teterin, D.E., Roshchina, I.A., 2007. Petrology of the
Hubert Miller Seamount, Marie Byrd Seamounts Province, West Antarctic, Southern Ocean. Doklady Earth Sciences 415A (6), 895–900. http://dx.doi.org/10.1134/
S1028334X07060141.
Uenzelmann-Neben, G., Gohl, K., 2012. Amundsen Sea sediment drifts: archives of
modifications in oceanographic and climatic conditions. Marine Geology
299–302, 51–62. http://dx.doi.org/10.1016/j.margeo.2011.12.007.
Watts, A.B., Koppers, A.A.P., Robinson, D.P., 2010. Seamount subduction and
earthquakes. Oceanography 23 (1), 166–173. http://dx.doi.org/10.5670/
oceanog.2010.68#sthash.6fn0xSSg.dpuf.
Weaver, S.D., Pankhurst, R.J., 1991. A precise Rb–Sr age for the Mandamus Igneous
Complex, North Canterbury, and regional tectonic implications. New Zealand
Journal of Geology and Geophysics 34, 341–345. http://dx.doi.org/10.1080/
00288306.1991.9514472.
1679
Weaver, S.D., Storey, B.C., Pankhurst, R.J., Mukasa, S.B., DiVenere, V.J.,
Bradshaw, J.D., 1994. Antarctica–New Zealand rifting and Marie Byrd Land
lithospheric magmatism linked to ridge subduction and mantle plume activity.
Geology 22, 811–814. http://dx.doi.org/10.1130/0091-7613(1994)022b0811:
ANZRAMN2.3.CO;2.
Wessel, P., Sandwell, D.T., Kim, S.-S., 2010. The global seamount census. Oceanography
23, 24–33. http://dx.doi.org/10.5670/oceanog.2010.60.
White, W.M., 2010. Oceanic island basalts and mantle plumes: the geochemical perspective. Annual Review of Earth and Planetary Sciences 38, 133–160. http://
dx.doi.org/10.1146/annurev-earth-040809-152450.
Willbold, M., Stracke, A., 2010. Formation of enriched mantle components by recycling
of upper and lower continental crust. Chemical Geology 276, 188–197. http://
dx.doi.org/10.1016/j.chemgeo.2010.06.005.
Wilson, J.T., 1963. Evidence from islands on the spreading of the ocean floor. Nature
197, 536–538. http://dx.doi.org/10.1038/197536a0.
Winterer, E.L., Sandwell, D.T., 1987. Evidence from en-echelon cross-grain ridges
for tensional cracks in the Pacific Plate. Nature 329, 534–537. http://dx.doi.org/
10.1038/329534a0.
Wobbe, F., Gohl, K., Chambord, A., Sutherland, R., 2012. Structure and breakup history
of the rifted margin of West Antarctica in relation to Cretaceous separation from
Zealandia and Bellingshausen Plate motion. Geochemistry, Geophysics, Geosystems
13, Q04W12. http://dx.doi.org/10.1029/2011GC003742.
Workman, R.K., Hart, S.R., 2005. Major and trace element composition of the depleted
MORB mantle (DMM). Earth and Planetary Science Letters 231, 53–72. http://
dx.doi.org/10.1016/j.epsl.2004.12.005.
Zindler, A., Hart, S.R., 1986. Chemical geodynamics. Annual Review of Earth and Planetary
Sciences 14, 493–571. http://dx.doi.org/10.1146/annurev.ea.14.050186.002425.