New Insights from Key Proterozoic Mineral Provinces

• Summary
• Download the presentation
• Further information

Summary

Ore deposits of Proterozoic age account for more than 90% of Australia’s known iron ore, uranium and lead resources, most of Australia’s known zinc (84%) and copper (71%) resources, and significant gold (17%) resources. Most of these deposits were formed by mineralising systems in the period 2000-1500 Ma, with the most fertile being the period 1690-1500 Ma. Recent GA regional projects conducted under the National Geoscience Agreement with State and NT partners have brought new understanding to the controls on distribution of these deposits.

The Gawler Craton project, conducted in partnership with PIRSA, defined a belt along the eastern margin of the craton that is prospective for iron oxide copper-gold-uranium deposits (IOCGU) associated with high-temperature 1590 Ma A-type granitoids. The major mineral deposits including Olympic Dam lie above a crustal-scale boundary defined by the GA Gawler seismic survey conducted in 2003. The IOCGU belt is spatially separate from gold mineralisation associated with I-type granitoids of the same age in the central Gawler Craton. Integrated geological, geophysical and geochemical studies have enabled development of a prospectivity map of the Gawler Craton that ranks domains in terms of their potential to host IOCGU deposits and provides a firmer framework for exploration.

Key outcomes from the Tanami Project, a partnership between GA, the NTGS, GSWA, and industry were a better understanding of the geology, geochronology, geochemistry and controls on lode-gold mineralisation in the Tanami region. A key feature is the identification of a major suture between the Tanami and Aileron Provinces, and recognition that mineral deposits in the region are associated with major crustal-penetrating shear zones and/or anticlinal stacks. The collision between the Tanami and Aileron crustal blocks is interpreted to have occurred prior to ~1840 Ma, as rocks of the overlying ~1700 Ma Tanami–Lander package blanket this suture.

The Paterson Project, conducted in partnership with GSWA, is ongoing and has already provided an improved basis for exploration through new magnetic, gravity, geochemistry and geochronology datasets. A significant outcome is the identification of a belt of 1590-1550 Ma igneous rocks that are potentially linked to a continent-wide event of metallogenic significance.

GA has also undertaken a synthesis of Proterozoic geological events to better define the event framework and geodynamic setting of key provinces during the period 2,000-1,000 Ma with the objective of predicting where undiscovered mineral systems may exist in relation to particular tectonic settings. The project has compiled available geological information to determine permissible tectonic settings which are then defined as polygons in a GIS of 2,000 – 1,000 Ma terranes age of the Australian continent.

The Prime Minister announced in August 2006 that the Government would provide $58.9 million over five years to GA to identify new onshore energy sources such as petroleum and geothermal energy. Three new national onshore projects focused on energy commodities have begun under the Onshore Energy Security Program (OESP)—uranium, hydrocarbon and geothermal. Data acquisition for these projects is underway, including a continent-wide radiometric survey that commenced in March and the National Geochemical Survey of Australia. The program will develop a better understanding of Australia’s geothermal potential through an improved database of heat flow information and use of geophysics to define the extent of buried high heat producing granites and other geothermal thermal sources. The National Geochemical Survey will sample transported regolith at outlets of ~1400 catchments and analyse samples from 2 depths for more than 60 elements.

The national-scale projects will be supported by targeted regional projects over two years to assess the potential for energy resources in specific regions. The projects will involve seismic reflection, airborne electromagnetic (AEM), magnetotelluric and other geophysical surveys, as well as multidisciplinary research through the acquisition of new geochronological, geological and geochemical data. Important early phases of these projects (to be undertaken in collaboration with State and Northern Territory geological surveys) will include the compilation of available information and the definition of specific scientific problems to guide new data acquisition, interpretation, synthesis and delivery phases. A key element will be deep regional seismic reflection surveys in targeted provinces, commencing with a major seismic survey in the Mount Isa–Georgetown–Charters Towers regions of northwest and north Queensland that will build on the 2006 Mt Isa seismic survey. Plans for follow-on seismic surveys aimed at delineating uranium, hydrocarbon, and geothermal potential are well advanced. AEM acquisition will define depth of cover over prospective basement, outline palaeochannel systems, and define structures in both basement and cover sequences in targeted provinces in the NT, SA and northern WA, commencing with a survey in the Paterson Province of WA.

The new OESP will deliver precompetitive data packages and fresh, scientifically based assessments of the potential for onshore energy resources such as oil, gas, uranium, thorium and geothermal energy and is expected to significantly boost investment in exploration for onshore energy resources.

Download the presentation slides

New Insights from Key Proterozoic Mineral Provinces (PDF 1.7MB)

Further information

For more information on the presentation please email James Johnson.
For information on the Onshore Energy Security Program please email Bill McKay.