Authors / CoAuthors
Apps, H.E. | Brodie, R.C. | Lawrie, K.C. | Highet, L.M. | Chan, R.A. | Gibson, D.L.
Abstract
The GILMORE project is a pilot study designed to test holistic systems approaches to mapping mineral systems and dryland salinity in areas of complex regolith cover. The project is coordinated by the Australian Geological Survey Organisation, and involves over 50 scientists from 14 research organisations. Research partners include: Cooperative Research Centres for Advanced Mineral Exploration Technologies (CRC AMET), Landscape Evolution and Mineral Exploration (CRC LEME), the CRC for Sensor Signal and Information Processing, and the Australian Geodynamics Cooperative Research Centre (AGCRC) Land and Water Sciences Division of Bureau of Rural Sciences (BRS) NSW Department of Land & Water Conservation and the NSW Department of Mineral Resources. Various universities including the Australian National University, University of Canberra, Macquarie University, Monash University, University of Melbourne, and Curtin University of Technology, and Australian National Seismic Imaging Resource (ANSIR). The project area lies on the eastern margin of the Murray-Darling Basin in central-west NSW. The project area was chosen for its overlapping mineral exploration (Au-Cu) and salinity management issues, and the availability of high-resolution geophysical datasets and drillhole materials and datasets made available by the minerals exploration industry. The project has research agreements with the minerals exploration industry, and is collaborating with rural land-management groups, and the Grains Research and Development Corporation. The study area (100 x 150 km), straddles the Gilmore Fault Zone, a major NNW-trending crustal structure that separates the Wagga-Omeo and the Junee-Narromine Volcanic Belts in the Lachlan Fold Belt. The project area includes tributaries of the Lachlan and the Murrumbidgee Rivers, considered to be two of the systems most at risk from rising salinities. This project area was chosen to compare and contrast salt stores and delivery systems in floodplain (in the Lachlan catchment) and incised undulating hill landscapes (Murrumbidgee catchment). The study area is characteristic of other undulating hill landscapes on the basin margins, areas within the main and tributary river valleys, and the footslopes and floodplains of the Murray-Darling Basin itself. Studies of the bedrock geology in the study area reveal a complex architecture. The Gilmore Fault Zone consist of a series of subparallel, west-dipping thrust faults, that juxtapose, from west to east, Cambro-Ordovician meta-sediments and granites of the Wagga Metamorphics, and further to the east, a series of fault-bounded packages comprising volcanics and intrusions, and siliciclastic meta-sediments. Two airborne electromagnetic (AEM) surveys were flown in smaller areas within the two catchments. Large-scale hydrothermal alteration and structural overprinting, particularly in the volcanics, has added to the complexity within the bedrock architecture. The data were originally published on 6 CDs. For ease of download the data have been zipped into the original structure. The contents are as follows: CD1 - An overview of the GILMORE Project with geophysical images, regolith map, drillhole locations, geophysical survey information and maghemite geochemistry. CD2 - Airborne Electromagnetic (AEM) images from the TEMPEST survey with vertical cross-sections linked to the flight lines CD3 - Integrated images of the Airborne Electromagnetic (AEM) data draped over the First Vertical Derivative of the Total Magnetic Intensity CD4 - Integrated images of the Airborne Electromagnetic (AEM) data draped over the First Vertical Derivative of the Total Magnetic Intensity CD5 - High resolution geophysical images from three detailed surveys and data from the Airborne Electromagnetic (AEM) QUESTEM survey CD6 - Geology, geochemistry, downhole data, 3 dimensional models, seismic data, and images linked to downhole point data.
Product Type
dataset
eCat Id
34652
Contact for the resource
Custodian
Owner
Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- GIS DatasetRegional
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- GIS
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- geophysics
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- magnetics
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- regolith
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- AEM
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- geology
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- AU-NSW
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_External
Publication Date
2001-01-01T00:00:00
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asNeeded
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geoscientificInformation
Series Information
Vol 2
Lineage
AIRBORNE ELECTROMAGNETICS (AEM) SURVEY Data Acquisition and Processing World Geoscience Corporation (WGC), now Fugro Airborne Surveys, flew the airborne electromagnetic survey under contract from January to March 1999 utilising the TEMPEST system developed by CRC AMET. The survey was flown at 150m line spacing along east-west lines. The nominal terrain clearance was 120m for the transmitter. The three component dB/dt towed bird receiver was towed 100 m behind and 5m below the aircraft. The TEMPESTsystem operated at a 25 Hz base frequency with a square waveform, 10 ms pulse width and average moment of 27,900 Am2. The sample rate of the receiver was 13 microseconds, giving the system a bandwidth of 25 Hz to 37.5 kHz. Streamed 13 microsecond data were recorded and later stacked into 0.2s (12 m) samples during processing. The stacked data were deconvolved using the high altitude reference waveform and the primary field was removed. These deconvolved ground response data were transformed to an equivalent B-field response for a perfect 100% duty cycle square wave. These data were binned into 15 windows with centres ranging from 13 microsecond to16.2 ms. AIRBORNE GEOPHYSICAL DATA Data have been compiled from 6 separate surveys. Magnetic and Gamma-ray Spectrometric Data The total magnetic intensity (TMI) point located data and each of the four channel (TC,K,U,TH) point located data for each survey were gridded separately at the optimal grid cell size of one fifth of the line spacing. From the composite TMI grid, the following grids were derived; -TMI reduced to the pole -First vertical derivative of TMI-RTP -Horizontal gradient of TMI REGOLITH Regolith landform units were compiled at 1:50 000 from interpretation of 1:60000 and 1:80 000 scale RC9 panchromatic aerial photographs and four weeks fieldwork. Subsidiary data was derived by analysis of drilling materials, down-hole geophysics, and airborne gamma-ray spectrometrics.
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Extents
[-35.0, -33.7, 147.0, 148.1]
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