Authors / CoAuthors
Goodwin, J.
Abstract
Two coincident, crustal-scale models, one of magnetic susceptibility and one of density, have been produced for a volume covering the Australian continent and extending down to 55.5 km depth. These models were produced using the UBC GIF MAG3D and GRAV3D inversion programs, respectively. The inversions were constrained with geological reference models with layers for sediments, undifferentiated crust and the mantle. The reference model for the magnetic inversion incorporated a Curie depth surface below which magnetic susceptibility was set to zero. Due to the size of the inversion problem to be solved, the volume was divided into 235 overlapping inversions, which were inverted separately and then recombined. The method of recombining the inversions relies on a cosine function to determine the weight of each property and then takes a weighted average. This method successfully attenuated the edge effects that would otherwise occur between models and allows them to be viewed as one seamless model that covers the whole of Australia. Regions of coincident high-density (>2.83 g/cm<sup>3</sup>) and high-magnetic susceptibility (>0.0125 SI) within the top 10 km of the undifferentiated crust (termed magnetite proxies) are suggested to be related to ultramafic rocks and the magnetite-forming hydrothermal alteration stages of potentially fertile IOCG systems (see download link: Magnetite region grids) . <b>Download Link & Description</b> <b>•</b> GA Record (.pdf) - The report describing the method and model results. PDF document. <b>•</b> Intermediate grids (.ers) - The Australia-wide intermediate grids of elevation, gravity, and total magnetic intensity. ERMapper (.ers) format. <b>•</b> Magnetite region grids (.ers, .tif) - The Australia-wide magnetite proxy regions projected onto a 2D surface. ERMapper (.ers) and GeoTiff (.tif) format. <b>•</b> Subset_[1-17] (.sg, .den, .sus) - The Australia-wide 3D density and magnetic susceptibility models in SGrid (.sg) and UBC-GIF (.den, .sus) formats. Also includes the geological reference model surfaces (.ts). <b>•</b> Individual inversion files - GRAV3D and MAG3D input and output files for the 235 individual UBC-GIF inversions (before being recombined using cosine weighting). <b>Individual inversion input/output files for A1-V2 are available on request from clientservices@ga.gov.au - Quote eCat# 149226</b> Due to their size, the Australia-wide models have been divided into subsets (labelled 1-17) for download. Please refer to the image below for the extent of the subsets.
Product Type
document
eCat Id
149226
Contact for the resource
Resource provider
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Point of contact
Digital Object Identifier
Keywords
- ( Project )
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- Geophysical Acquisition and Processing Section
- ( Project )
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- Australian Resources Framework
- ( Project )
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- EFTF – Exploring for the Future
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- Total Magnetic Intensity (TMI)
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- gravity
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- Magnetic Susceptibility
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- density
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- geophysical inversion
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- UBC-GIF
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- MAG3D
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- GRAV3D
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- full-crustal
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- 3D model
- theme.ANZRC Fields of Research.rdf
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- Magnetism and palaeomagnetismGravimetrics
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- Published_External
Publication Date
2024-10-10T03:09:11
Creation Date
2024-03-06T12:00:00
Security Constraints
Legal Constraints
Status
completed
Purpose
This GA Record documents the method for how the first seamless, crustal-scale, Australia-wide models of density and magnetic susceptibility were produced. It is combined with a release of the models and their supporting data.
Maintenance Information
asNeeded
Topic Category
geoscientificInformation
Series Information
GA Record 2024/54
Lineage
<div>Produced by the Geophysical Acquisition and Processing Section. A continuation of work presented by Goodwin and Lane (2021) on the North Australian Craton (NAC) 3D density and magnetic susceptibility models.</div> <div>Version 1.1 Updates (13/01/2025): <br> • Fixed an issue in the recombined density models where values increased towards the edges of the model. <br> • Included an SGrid format for the density and magnetic susceptibility models (see subsets 1-17). <br> </div>
Parent Information
Extents
[-44, -9, 112, 154]
Reference System
Spatial Resolution
Service Information
Associations
Downloads and Links
Download Record (pdf) [12.5 MB]
Download Intermediate grids (.ers) [169.5 MB]
Download Magnetite region grids (.ers, .tif) [6.4 MB]
Download subset 1 (zip) [344.8 MB]
Download subset 2 (zip) [285.7 MB]
Download subset 3 (zip) [272.3 MB]
Download subset 4 (zip) [324.8 MB]
Download subset 5 (zip) [290.8 MB]
Download subset 6 (zip) [205.7 MB]
Download subset 7 (zip) [322.2 MB]
Download subset 8 (zip) [330.5 MB]
Download subset 9 (zip) [233.3 MB]
Download subset 10 (zip) [293.0 MB]
Download subset 11 (zip) [298.3 MB]
Download subset 12 (zip) [318.8 MB]
Download subset 13 (zip) [194.4 MB]
Download subset 14 (zip) [218.1 MB]
Download subset 15 (zip) [321.5 MB]
Source Information