Authors / CoAuthors
Foss, C. A. | Hope, J. | Patabendigerada, S. | Hope, J. | Foss, C. A.
Abstract
<div>As part of the Australia's Resources Framework Project, in the Exploring for the Future Program, Geoscience Australia and CSIRO have undertaken a magnetic source depth study across four areas. These are: 1) the western part of Tasmania that is the southernmost extension of the Darling-Curnamona-Delamerian (DCD) project area; 2) northeastern Queensland; 3) the Officer Basin area of western South Australia and southeastern West Australia; and 4) the 'Eastern Resources Corridor' (ERC) covering eastern South Australia, southwest Queensland, western New South Wales and western Victoria. This study has produced 2005 magnetic estimates of depth to the top of magnetization. The solutions are derived by a consistent methodology (targeted magnetic inversion modelling, or TMIM; also known as ‘sweet-spot’ modelling). </div><div><br></div><div>The magnetic depth estimates produced as part of this study provide depth constraints in data-poor areas. They help to construct a better understanding of the 3D geometry of the Australian continent, and aid cover thickness modelling activities. </div><div><br></div><div>A supplementary interpretation data release is also available through Geoscience Australia's enterprise catalogue (ecat) at https://pid.geoscience.gov.au/dataset/ga/149499.</div><div><br></div><div>Geoscience Australia’s Exploring for the Future program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to net zero emissions, strong, sustainable resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government. This work contributes to building a better understanding of the Australian continent, whilst giving the Australian public the tools they need to help them make informed decisions in their areas of interest.</div>
Product Type
dataset
eCat Id
149239
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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- Australia’s Resources Framework
- ( Project )
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- EFTF – Exploring for the Future
- ( Project )
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- Darling-Curnamona-Delamerian
- ( Project )
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- Officer-Musgrave-Birrindudu
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- Magnetics
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- depth estimates
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- cover modelling
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- 3D geological model
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- cover thickness
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- depth to basement
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- EGGS
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- Estimates of Geological and Geophysical Surfaces Database
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- Eastern Resources Corridor
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- Darling-Curnamona-Delamerian (DCD)
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- ARF - Australia’s Resources Framework
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- ARF
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- DCD
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- ERC
- theme.ANZRC Fields of Research.rdf
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- Magnetism and palaeomagnetismApplied geophysics
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- Published_External
Publication Date
2024-05-29T07:08:40
Creation Date
2024-04-03T04:00:00
Security Constraints
Legal Constraints
Status
Purpose
This study exclusively used aeromagnetic data publicly available by download from either Geoscience Australia’s GADDS (Geophysical Archive Data Delivery System) portal or from Mineral Resources Tasmania, Geological Survey of Queensland, Geological Survey of Western Australia, Geological Survey of South Australia, Geological Survey of New South Wales, and Geological Survey of Victoria. Much of this data has been acquired as part of exploration initiative programs to encourage and provide support for geological mapping and mineral exploration. In most cases the surveys were flown on either east-west or north-south flightlines at line spacings of between 100 and 400 m and with terrain clearances of 60 to 100 m. We generated depth to magnetisation estimates on flightline data using the TMIM (targeted magnetic inversion modelling) or ‘sweet-spot’ method, which is a semi-automated inversion process. Solutions were generated from a selection of suitable magnetic field features chosen to sample anomalies of different characteristics and clearly different source depths. In some areas, the combination of suitable magnetisations and appropriately located flightlines produce many sweet-spots from which a selection can be chosen. In other areas of fewer sweet-spots a compromise is required in selection of less suitable anomalies that yield less reliable depth values. In all cases for this study, the magnetic data were modelled with tabular bodies, and the body parameters (including depth to top body, body width, strike length, depth extent, dip, dip azimuth, and magnetic susceptibility (SI units)) are included in the Estimates of Geological and Geophysical Surfaces (EGGS) spreadsheets released as a supplementary interpretation data package (https://pid.geoscience.gov.au/dataset/ga/149499). We also assign a subjective measure of ‘depth confidence’ with values of high (H), moderate (M) and low (L); in some instances we also use ‘moderately high’ (HM), and ‘moderately low’ (ML), to reduce step differences in the size of the resulting uncertainty values). These subjective estimates are made from evaluation of the data quality and confidence with which the magnetic field variation is defined, together with evaluation of the suitability of the expected source geometry to support depth estimation. Data quality also incorporates the confidence with which the ground surface can be located. The expected shape of field variations over magnetisations most suitable for source depth estimation can be reasonably predicted and sought-for. We considered these key factors in assigning the depth confidence classification and then use that classification to assign a percentage ‘depth uncertainty’ value. The depth uncertainty value is highly subjective and is indicative only. We assigned an uncertainty of 10% of depth from sensor elevation to the estimated top of magnetisation for ‘high’ confidence values, 25% for ‘moderate’ and 40% for ‘low’ confidence values (low confidence solutions were only used where no other solution was available in the vicinity). ‘Moderately high’ and ‘moderately low’ solutions have percentage uncertainties of 20% and 30% respectively. The aim of this dataset is to provide depth constraints in data-poor areas. They help to construct a better understanding of the 3D geometry of the Australian continent, and aid cover thickness modelling activities. This work, especially when combined with the supplementary interpretation data package, contributes to building a better understanding of the Australian continent, whilst giving the Australian public the tools they need to help them make informed decisions in their areas of interest.
Maintenance Information
asNeeded
Topic Category
geoscientificInformation
Series Information
Lineage
<div>The study began in late 2021, and was initially focused on generating targeted magnetic inversion model (TMIM) magnetic depth estimates over the ERC and Western Tasmania areas to support work in the regional Darling-Curnamona-Delmarian project. In 2022, the project was expanded to acquire additional TMIM estimates across the Officer Basin and northeast Queensland areas, to add to the national coverage of TMIM magnetic depth estimates in the Estimates of Geological and Geophysical Surfaces (EGGS) database.</div><div><br></div><div>All magnetic estimates were generated using Tensor Research's ModelVision software, initially in version 17.0 and then using version 17.5. </div><div><br></div><div>This dataset includes QGIS project deliverables of hyperlinked model images for each of the depth estimate points as well as the national magmap version 7 (2019) gridded data. A report summarising the methodology employed for generating the magnetic depth estimates and describing the results is also provided as part of this dataset release.</div><div><br></div><div>The excel spreadsheets uploaded into EGGS are provided for each of the four study areas (ERC, Tasmania, northeast Queensland and Officer Basin) as a supplementary dataset, and are available at https://dx.doi.org/10.26186/149499. </div>
Parent Information
Extents
[-44.00, -9.00, 112.00, 154.00]
Reference System
GDA94 / geographic 2D (EPSG: 4283)
Spatial Resolution
Service Information
Associations
Association Type - largerWorkCitation
Estimates of Geological and Geophysical Surfaces (EGGS) database
eCat Identifier - 126254,
UUID - 426402a1-df24-43b2-9943-84399344240c
Association Type - largerWorkCitation
Putting all your EGGS in one basket: the Estimates of Geological and Geophysical Surfaces database
eCat Identifier - 132526,
UUID - 23fcf14a-34eb-429a-adeb-7b1200e9716f
Association Type - generated
Regional magnetic depth estimates for Eastern Resources Corridor (ERC), Officer Basin, Tasmania and Northeast Queensland -- Interpretation Data Package
eCat Identifier - 149499,
UUID - 9df7d633-f2a0-48eb-bb59-2c674a53c6b8
Source Information