Product catalogue
The North Australian Craton 3D Gravity and Magnetic Inversion Models - A trial for first pass modelling of the entire Australian continent
As part of the Exploring for the Future program, whole-of-crust 3D gravity and magnetic inversion models have been produced for an area encompassing the North Australia Craton. These models were created to aid 3D geological mapping and identification of large-scale mineral systems such as those associated with iron oxide copper-gold deposits.
The inversion models were derived using the University of British Columbia - Geophysical Inversion Facility MAG3D and GRAV3D programs. The inversions were constrained with geological reference models that had layers for Phanerozoic sediments, Proterozoic 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.
To allow cross-referencing, both the density and magnetic susceptibility models were designed to occupy the same physical space with identical volumes and cell sizes. A horizontal cell size of 1 km was used with 61 vertical layers, whose thickness increased with depth. The area of interest is 2450 km by 1600 km and extends to a depth of 70 km below the geoid, resulting in a total volume with ~239 million cells. Ultimately, it was not possible to invert a model of this size. Instead, the volume was broken down into a grid of overlapping tiles with 8 rows and 10 columns. Each tile was independently inverted before being recombined into a single coherent output model.
When the overall model was reconstructed using the core region of each tile, some low-level edge effects were observed, increasing in significance with depth. These effects were satisfactorily attenuated by applying cosine weighting from the centre of each tile out to the edge of the overlap region during reconstruction.
The coincident density and magnetic susceptibility models show a relationship with known iron oxide copper-gold deposits and regions of >2.80 g/cm3 and >0.01 SI in the Tennant Creek and Cloncurry regions. It is suggested that these regions of high-density and high-magnetic susceptibility are related to the magnetite-forming hydrothermal alteration stages of an iron oxide copper-gold deposit.
The success of the NAC modelling exercise has demonstrated that this method can be expanded to produce coincident gravity and magnetic inversion models for the entire Australian region.
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DOWNLOADS
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Input Data: The input gravity, magnetic and elevation data (.ers and .tif).
Geological Reference Models: The geological reference model as surfaces and 3D volumes (.sg, .ts, and UBCGIF).
Observed vs Predicted Data: The input gravity/magnetic data compared to the predicted data (.png).
Recombined Models: The recombined (cosine weighted) density and magnetic susceptibility models (.sg, and UBCGIF).
Magnetite Proxies: Proxies for magnetite alteration related to IOCG deposits (.ers).
Video: Video describing the method and results (.mp4).
Simple
Identification info
- Date (Creation)
- 2021-10-01
- Date (Publication)
- 2021-12-15T02:42:43
- Citation identifier
- Geoscience Australia Persistent Identifier/https://pid.geoscience.gov.au/dataset/ga/145901
- Citation identifier
- Digital Object Identifier/http://dx.doi.org/10.11636/Record.2021.033
- Cited responsible party
-
Role Organisation / Individual Name Details Author Goodwin, J.A.
External Contact Author Lane, R.J.L.
External Contact
- Name
-
Record
- Issue identification
-
RECORD 2021/033
- Purpose
-
GA Record and associated 3D models
- Status
- Completed
- Point of contact
-
Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Point of contact Goodwin, J.
MEG Internal Contact Resource provider Minerals, Energy and Groundwater Division
External Contact
- Spatial representation type
Spatial resolution
- Level of detail
-
1000 m horizontal cell size
- Topic category
-
- Geoscientific information
Extent
Extent
))
Vertical element
- Minimum value
- 1500
- Maximum value
- -70000
Identifier
- Codespace
-
EPSG
- Version
-
8.6
- Maintenance and update frequency
- As needed
Resource format
- Title
-
Product data repository: Various Formats
- Website
-
Data Store directory containing the digital product files
Data Store directory containing one or more files, possibly in a variety of formats, accessible to Geoscience Australia staff only for internal purposes
- theme.ANZRC Fields of Research.rdf
-
-
EARTH SCIENCES
-
- Product
-
-
density
-
- Product
-
-
magnetic susceptibility
-
- Process
-
-
3D inversion
-
- Place
-
-
North Australian Craton
-
- Process
-
-
cosine weighting
-
- Process
-
-
UBC-GIF
-
- Process
-
-
MAG3D
-
- Process
-
-
GRAV3D
-
- Project
-
-
Exploring for the Future
-
- Project
-
-
EFTF
-
- Keywords
-
-
Published_External
-
Resource constraints
- Title
-
Creative Commons Attribution 4.0 International Licence
- Alternate title
-
CC-BY
- Edition
-
4.0
- Access constraints
- License
- Use constraints
- License
Resource constraints
- Title
-
Australian Government Security ClassificationSystem
- Edition date
- 2018-11-01T00:00:00
- Classification
- Unclassified
- Language
- English
- Character encoding
- UTF8
Distribution Information
- Distributor contact
-
Role Organisation / Individual Name Details Distributor Commonwealth of Australia (Geoscience Australia)
Voice
- OnLine resource
-
Download the Record (pdf) [17.6 MB]
Download the Record (pdf) [17.6 MB]
- Distribution format
-
-
pdf
-
- OnLine resource
-
Download the input data [157 MB]
Download the input data [157 MB]
- Distribution format
-
-
ers tfw tif txt
-
- OnLine resource
-
Download the geological reference model [1.58 GB]
Download the geological reference model [1.58 GB]
- Distribution format
-
- OnLine resource
-
Download the observed vs predicted data [75.1 MB]
Download the observed vs predicted data [75.1 MB]
- Distribution format
-
- OnLine resource
-
Download recombined models [2.7 GB]
Download recombined models [2.7 GB]
- Distribution format
-
- OnLine resource
-
Download the magnetite proxies [490 KB]
Download the magnetite proxies [490 KB]
- Distribution format
-
-
ers
-
- OnLine resource
-
Download the video (mp4) [345 MB]
Download the video (mp4) [345 MB]
- Distribution format
-
-
mp4
-
Resource lineage
- Statement
-
Models completed in 2021.
Reference System Information
- Reference system identifier
- EPSG/GDA94 / Australian Albers (EPSG:3577)
Metadata constraints
- Title
-
Australian Government Security Classification System
- Edition date
- 2018-11-01T00:00:00
- Classification
- Unclassified
Metadata
- Metadata identifier
-
urn:uuid/62226edb-0487-4311-be5c-57c969f0bdbb
- Title
-
GeoNetwork UUID
- Language
- English
- Character encoding
- UTF8
- Contact
-
Role Organisation / Individual Name Details Point of contact Commonwealth of Australia (Geoscience Australia)
Voice Owner Goodwin, J
Internal Contact Point of contact Goodwin, J.
MEG Internal Contact
Type of resource
- Resource scope
- Document
- Name
-
GA publication: GA Record
Alternative metadata reference
- Title
-
Geoscience Australia - short identifier for metadata record with
uuid
- Citation identifier
- eCatId/145901
- Date info (Creation)
- 2019-04-08T01:55:29
- Date info (Revision)
- 2019-04-08T01:55:29
Metadata standard
- Title
-
AU/NZS ISO 19115-1:2014
Metadata standard
- Title
-
ISO 19115-1:2014
Metadata standard
- Title
-
ISO 19115-3
- Title
-
Geoscience Australia Community Metadata Profile of ISO 19115-1:2014
- Edition
-
Version 2.0, September 2018
- Citation identifier
- https://pid.geoscience.gov.au/dataset/ga/122551