0 XXX, 0000 Our Ref - Mineral Resources Tasmania

0 XXX, 0000 Our Ref - Mineral Resources Tasmania
REPORT
GROUND MAGNETICS SURVEY
Long Plains, Savage River
Tasmania
POST-ACTIVITY REPORT
Gap Geophysics Australia Pty Limited
[ABN 67 116 407 580]
Project Reference:
08065ABMS
Prepared For:
Australian Bulk Minerals
Issuing Office:
Brisbane Office
Date of Issue:
June 2008
© Gap Geophysics Australia Pty Limited, 2008
COMMERCIAL IN CONFIDENCE
Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
DISCLAIMER AND COPYRIGHT NOTICE
GAP GEOPHYSICS AUSTRALIA PTY LIMITED
DISCLAIMER
Please Read This Disclaimer
This Disclaimer is an important legal document. The use of this report is governed by and subject to this
Disclaimer.
The Client
The entity who commissioned this report and whis Gap Geophysics Australia Pty Limited’s (GAP’s)
client is Australian Bulk Minerals (ABMS).
Purpose of This Report
This report was commissioned for the purpose of a sub-surface geophysical investigation to map
geological features.
Disclaimer
GAP accepts no responsibility or liability for any use of this report or any reliance upon this report by any
person, other than the use of the whole of this report by the Client consistent with the Purpose.
GAP accepts no responsibility or liability to any person who relies upon a part of this report. This report
must at all times be considered in its entirety.
COPYRIGHT
Copyright
GAP is the owner of the copyright subsisting in this report.
License
GAP grants to the Client a non-exclusive license for the full term of copyright throughout the world to
use and reproduce this Report for any reason consistent with the Purpose.
Infringement
The reproduction of any part of this report by any person other than the Client, or for any reason not
consistent with the Purpose is an infringement of copyright, and will be prosecuted by GAP.
Report prepared by: ________________
Lucas Heape
Project Manager
Copy Number
1
2
3
© Gap Geophysics Australia Pty Limited, 2008
DOCUMENTATION CONTROL
Issued To
Australian Bulk Minerals
Australian Bulk Minerals
Gap Geophysics Australia Pty Limited
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
Table of Contents
EXECUTIVE SUMMARY............................................................................................. 4
SCOPE AND OBJECTIVES OF THE SURVEY.......................................................... 4
PROJECT PERSONNEL ............................................................................................ 4
SURVEY PROCEDURE AND INSTRUMENTATION ................................................. 5
SURVEY RESULTS .................................................................................................... 6
FINAL REMARKS ....................................................................................................... 8
APPENDIX A – IMAGES ............................................................................................ 9
Instrumentation .......................................................................................................................................................................13
The TM-6 Magnetometer .....................................................................................................................................................13
Base-Station ........................................................................................................................................................................14
© Gap Geophysics Australia Pty Limited, 2008
COMMERCIAL IN CONFIDENCE
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
GROUND MAGNETICS SURVEYS
POST-OPERATIONS REPORT
Long Plains, Savage River, Tasmania
EXECUTIVE SUMMARY
Gap Geophysics Australia Pty Limited (GAP) was commissioned by Australian Bulk Minerals to conduct
geophysical surveys using Ground Magnetics over one area at Long Plains, Savage River. The survey
was carried out during the period 8th to 10th May 2008.
SCOPE AND OBJECTIVES OF THE SURVEY
The Statement of Work (SOW) specified that GAP was to utilise its Ground Magnetics technology to
survey (in AMG/AGD 66 Zone 55 coordinates) one areas totalling approximately 4 line km.
The deliverables for the project were as follows:

A brief report on field activities.

A digital copy of the Total Magnetic Intensity data in ASCII XYZ and CSV (.XYZ) format.

A digital copy of the Total Magnetic Intensity and data in Geosoft grid (.GRD) format.

Colour images of the processed data as JPEG images.
PROJECT PERSONNEL
The Client representative was Michael Everitt for Australian Bulk Minerals who arranged the survey and
provided on site assistance. Lucas Heape led the project for GAP, with field operations carried out by
Lucas Heape, Glen Uebergang and Alyson Foster.
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COMMERCIAL IN CONFIDENCE
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
SURVEY PROCEDURE AND INSTRUMENTATION
A summary of the instrumentation and data processing parameters applied to the surveys is shown in
Table 1.
Roving Magnetometer Acquisition System
Magnetometer
Geophysical Technology TM-6 Magnetometer Controller
- Synchronised with GPS 1PPS pulse
Sensor
Geometrics 822AS Cs Vapour
Sensor Elevation
~2.0 m
Sample Rate
1200 Hz
Sample Resolution
0.01nT
Base Station
Magnetometer
Geometrics G856 Proton Precession
Sample Rate
0.1 Hz
Sample Resolution
0.1 nT
Navigation & Positioning
GPS
UBlox
Differential Corrections
None applied
Software
SurvNav - Gap Geophysics Australia Pty Limited
Datum
AGD 66 / - AMG Zone 55
Sample Rate
1 Hz
Nominal Survey Direction
East West
Nominal Line Spacing
25m or where line traverses were cut
Data Processing Parameters
Table 1
TMI Sample Interval
~ 0.05m
Gridding
Minimum Curvature
Cell Size
5m
TMI Filtering
None unless specified.
Images Produced
TMI, TMI_RTP,TMI_1VD
Instrumentation and data processing parameters used for the survey.
© Gap Geophysics Australia Pty Limited, 2008
COMMERCIAL IN CONFIDENCE
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
SURVEY RESULTS
The data were processed as described in Appendix B. Colour images of the data were produced and
are provided on the accompanying CD as JPEG images.
Images were produced of the following:




Survey Map - This map shows survey area with line paths and numbers coloured black.
Colour Image of Total Magnetic Intensity (TMI).
Colour Image of Total Magnetic Intensity – Reduced to Pole (TMI_RTP).
Colour Image of Total Magnetic Intensity – First Vertical Derivative (TMI_1VD).
Reduced scale copies of the images have been included in Appendix A for reference.
© Gap Geophysics Australia Pty Limited, 2008
COMMERCIAL IN CONFIDENCE
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
DIGITAL DATA PRODUCTS
The following files are supplied on the accompanying CD for each of the survey grids:
Files
Description
Grid Name.xyz
TMI in Geosoft XYZ Format
Grid Name.gdb
TMI in Geosoft Database Format
Grid Name TMI.grd
TMI grid file in Geosoft Format
Grid Name TMI RTP.grd
TMI Reduced to Pole grid file in Geosoft Format
Grid Name TMI .jpg
Colour Image of TMI in JPEG Format
Key:



TMI – Total Magnetic Intensity
RTP – Reduced To Pole
1VD – First Vertical Derivative
Also included on the CD is a copy of this report in Portable Document Format (PDF).
© Gap Geophysics Australia Pty Limited, 2008
COMMERCIAL IN CONFIDENCE
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
FINAL REMARKS

Data collection at Long Plains was carried out along lines cut through thick scrub and forest.
Lines are of irregular length and whilst the typical line spacing was 25m the southern end of the
grid had some lines 50m apart.

Due to the thick tree cover at Long Plains differential GPS (DGPS) was not utilised. An
OmniSTAR DGPS was trialled but found to be less accurate than a newer high gain non DGPS
unit (Ublox).

The survey was carried out in wet, drizzly weather which led to water laden foliage in the cover
above. It is likely that this contributed to the reduced satellite visibility and therefore the
accuracy of the GPS.

The poor positional information caused problems with the ABMS crew cutting lines. Some of the
lines from this survey varied enough to join into other lines. Where this has occurred the GAP
crew has bush bashed as much as possible to complete the required lines.

The data from the January 2007 and from this current survey were combined to form the grids
and images contained in this report. The data presented on the CD also a combination of the
two data sets.
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COMMERCIAL IN CONFIDENCE
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
APPENDIX A – IMAGES
Figure 1
Long plains grid Survey Area - showing the survey line paths from both 2007
and 2008 surveys.
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COMMERCIAL IN CONFIDENCE
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
Figure 2
Long Plains Grid – colour image of Total Magnetic Intensity.
© Gap Geophysics Australia Pty Limited, 2008
COMMERCIAL IN CONFIDENCE
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
Figure 3
Long Plains Grid – colour image of TMI Reduced to Pole (RTP).
© Gap Geophysics Australia Pty Limited, 2008
COMMERCIAL IN CONFIDENCE
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
Figure 4
Long Plains Grid – colour image of TMI First vertical Derivative (1VD).
© Gap Geophysics Australia Pty Limited, 2008
COMMERCIAL IN CONFIDENCE
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
Instrumentation
The TM-6 Magnetometer
A Geophysical Technology Model TM-6 magnetometer controller was used in conjunction with a
caesium-vapour magnetometer sensor for this survey. The TM-6 was programmed to record Total
Magnetic Intensity (TMI) readings to a resolution of 0.01nT. Measurements were logged to the TM-6
flash memory at a rate of 1200 per second.
In hand-held magnetic survey mode, the TM-6 normally requires two operators, one of whom holds the
sensor (see Figure 5). The sensor is connected to the controller by a 5m coaxial cable, which enables
the sensor to be separated from the controller by sufficient distance to ensure that the sensor is free
from any magnetic interference produced by the control electronics. GAP utilises differential GPS with
the Ground Magnetics acquisition system to assist survey navigation and positioning. This obviates the
costly requirement for the client to establish control grids in the survey areas.
The TM-6 system employs GAP’s proprietary TM6-UI navigation software running on a hand-held
computer and coupled with a Trimble AgGPS-132 differential GPS, using Fugro OmniStar real-time
differential corrections. The accuracy of the DGPS is described as less than 1m.
In Handheld mode the TM-6 and GPS units are mounted in a backpack as shown in Figure 6. Also
included in the backpack are batteries to power the units and a warning system should any of the
instruments malfunction.
Figure 5
The TM-6 magnetometer system in hand-held configuration. The operators
are separated by a distance of up to 5m to minimise magnetic interference
from the controller.
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
For hand held operation the Cs vapour magnetometer sensor and GPS antenna are mounted on a
second backpack, which enables variable sensor height. A typical sensor configuration is shown in
Figure 7.
Accurate timing information is provided via the AgGPS-132 receiver which outputs a 1s “strobe” pulse
every second. The strobe pulses are logged by the TM-6 in between Total Magnetic Intensity readings,
thus providing the GPS time-reference for magnetic field measurements.
Base-Station
A Geometrics G856 proton precession magnetometer is used to record temporal changes in the Earth’s
magnetic field. The magnetometer is generally set to record Total Magnetic Intensity readings to a
precision of 0.1nT once every 10 seconds.
The base-station magnetometer is located at safe distances from likely sources of cultural magnetic
noise during the surveys. Diurnal variation data is calculated as the base-station reading minus the
approximate average value at the base-station site(s) used for these surveys.
Figure 6
Backpack showing the TM-6 magnetometer controller, Trimble Ag-132
differential GPS unit and hand held PC’s, for navigation and survey controls.
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Project No. 08065ABMS
Ground Magnetics Survey – Long Plains, Savage River, Tasmania
08065ABMS_Report_v01
Figure 7
Typical sensor configuration showing the Cs vapour sensor on the left at a
survey height of 2.5m. The GPS antenna is mounted on the right side of the
backpack.
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