Gawler Craton 3D model

• About the Gawler Craton 3D model
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About the Gawler Craton 3D model

This is the 2nd version of the 3D model provided to demonstrate the current direction of the Gawler Project's research. New data and features include: new gravity and magnetics images, "strings", basement units, inversion models, iso-surfaces and improved navigation features.

Geographic extent

Eastern Gawler Craton, South Australia.

Contents

Digital elevation model, magnetics and gravity images, basement topography, cross-sections, fault planes, "strings", basement units and inversion models.

Size

Around 30 MB. Startup download is around 100 KB - the remaining datasets download when selected.

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Metadata

This VRML model has been developed to assist in visualising and understanding the three-dimensional distribution of principal geological elements within the Earth's crust across the Olympic Copper-Gold province of South Australia, which hosts the giant Olympic Dam deposit.

Knowledge of spatial and temporal relationships between crustal architecture, the generation of structures and fluid flow is essential to understanding a mineral system. In regions dominated by cover, as in the Olympic province, such knowledge strongly depends on interpretation of potential field data.

A large number of datasets have been included in the model, but most of the interpretation is based on regional gravity and magnetic data compilations. The magnetic grid is a composite, compiled by Geoscience Australia from more than a hundred individual airborne surveys.

• Specifications for the individual surveys, which comprise the gravity and magnetic compilations are available from Geoscience Australia.
• Data for individual surveys are available by accessing the SARIG website of PIRSA Minerals.
• Contact the project leader, Roger Skirrow, for more information regarding the datasets included in the model. Alternatively, check the metadata pages within the model for more information.

A significant component of our modelling used the potential field inversion software, MAG3D and GRAV3D, developed at the University of British Columbia Geophysical Inversion Facility (UBC-GIF). Hitherto, the MAG3D and GRAV3D programs have largely been used at the deposit-scale, but we have modified the approach and settings for use at a regional-scale.

The volume of crust chosen for the inversion modelling is a subset of the Olympic province centred on the Olympic Dam deposit and measuring 150 kmx 150 kmy 10 kmz with cells of 1 km 1 km 0.5 km. It comprises Archaean granulites, Palaeoproterozoic orthogneiss and metasediments (including BIFs), and early Mesoproterozoic felsic and mafic intrusives and extrusives. Zones of magnetite, haematite, and sulphides are distributed throughout the upper parts of the crustal volume, providing clear targets for magnetic and gravity data.

Results of inversions included in the VRML model are our interpretations of possible distributions of structures, units and alteration distribution. We have used constrained inversions of the potential field data to restrict the infinite number of possible models to a single model of densities and susceptibilities that is consistent with both our limited understanding of the geology of the area and the observed regional magnetic and gravity data.

The VRML model presented here reflects an estimate of the major geological features of the crystalline basement in the area. The model may be significantly improved and refined with the addition of more geological constraints and ground-truthing.