A 3D map of the Cooper Basin region has been produced over an area of 300 x 450 km to a depth of 20 km (Figure 1). The 3D map was constructed from 3D inversions of gravity data using geological data to constrain the inversions. It delineates regions of low density within the basement of the Cooper/Eromanga Basins that are inferred to be granitic bodies. This interpretation is supported by a spatial correlation between the modelled bodies and known granite occurrences. The 3D map, which also delineates the 3D geometries of the Cooper and Eromanga Basins, therefore incorporates both potential heat sources and thermally insulating cover, key elements in locating a geothermal play. This study was conducted as part of Geoscience Australia's Onshore Energy Security Program, Geothermal Energy Project. This 3D data release constitutes the first version of the Cooper Basin region 3D map. A future data release (version 2 of the 3D map) will extend the area to the north and east to encompass the entire Queensland extension of the Cooper Basin. The version 2 3D map will incorporate more detailed 3D models of the Cooper and Eromanga Basins by delineating the major internal sedimentary sequences within the basins. Thermal properties will then be incorporated into the 3D map to produce a 3D thermal model. The goal is to produce a 3D thermal model of the Cooper Basin region that not only matches existing temperature and heat flow data in the region, but also predicts regions of high heat flow and elevated temperatures in regions where no heat flow or temperature data exists.

Within the Central Australian region, nominally constrained by 22.5oS 134oE and 31.5oS 144oE for this study, lie several systems of stacked basins beneath the extensive Mesozoic Eromanga Basin. Remnants of Proterozoic basins are largely inferred from gravity, unexplored, and are not everywhere differentiated from an extensive cover of the lower Palaeozoic Warburton Formation. This sequence is the central link between the contiguous Amadeus, Officer and Georgina Basins, and the Thomson Fold Belt. Since the Carboniferous, the region has largely experienced intracratonic sag and has accumulated continental sediments, including thick coal measures, with intermittent tectonism and uplift. In late Early Cretaceous, marine conditions briefly invaded this subsiding region, but continental sedimentation resumed in the Late Cretaceous. Tectonism occurred in the Tertiary with basin inversion and subsequent formation of the Great Artesian Basin. In the Cainozoic, the region is again in subsidence and accommodating fluvial and aeolian sediment slowly into the Eyre Basin. The preserved depocentres of the Carboniferous-Permian-Triassic Cooper, Pedirka-Simpson, and Galilee Basins are spatially separate, although all contain comparable, largely organically-mature continental coal measure sequences.

Valuable new insights into the distribution and geological settings of U, Th and K rich (HHP) granites in Australia have come from interrogation of national datasets, supplemented by wide-ranging regional studies and inversion modelling conducted under a major Government energy security initiative. The increasing attention being paid to these granites in Australia reflects their importance in relation to geothermal energy and uranium mineralisation, which will be outlined. The oldest HHP granites in Australia are potassic, siliceous I-type late Archean (2.85 and 2.65-2.63 Ga) granites in the Pilbara and Yilgarn Cratons, Western Australia. These were produced by melting of Archean TTG-rich crust. The HHP granites were produced on a massive craton-wide scale in a geodynamic environment that is poorly understood, although high geothermal gradients appear necessary. This magmatism effectively redistributed U and Th into the middle and upper crust and stabilized the Pilbara and Yilgarn Cratons. The Proterozoic in Australia, particularly in the age range 1.8-1.5 Ga, is typified by granites with high K and, locally, very high U and Th abundances. In general, these HHP granites were also emplaced late in the evolution of the Proterozoic crust and are considered to be the result of crustal reworking, under high geothermal gradients. It is probable that there was associated crustal thinning, and mantle contributions of heat and some material. I- and S-type HHP granites also occur within the Australian Paleozoic. Their chemical compositions, including the elevated U and Th contents in the majority of these rocks, reflect extensive and efficient fractional crystallisation processes in magmas derived predominantly by crustal melting. Geodynamic environments are considered to range from late syn-tectonic, to post-collisional and back-arc extension.

Work conducted at the Bureau of Mineral Resources (now Geoscience Australia) in the early 1990s was instrumental in bringing hot rocks geothermal research and development to Australia. Following the announcement of the Australian Government's Energy Initiative in August 2006, a new geothermal project has been started at Geoscience Australia. This paper, presented at 3rd Hot Rock Energy Conference in Adelaide, August 2007, outlines the scope of the Onshore Energy Security Program and the development, implementation and progress to date of the Geothermal Energy Project.

Geoscience Australia's $58.9M 5-year Onshore Energy Security Program began in 2006 and included a new Geothermal Energy Project. The OESP concluded in June 2011 but the Geothermal Energy Section continues albeit with reduced funding. The project aims to assist the development of a geothermal industry in Australia by: providing precompetitive geoscience information, including acquisition of new data; informing the public and government about Australia's geothermal potential; providing technical advice to government; and partnering with industry in international promotional events for the purpose of attracting investment. This abstract gives a brief summation of activities undertaken by Geoscience Australia within the Onshore Energy Security Program potentially of interest to geothermal explorers.

Extended abstract describing metallogenic significance of georgina-Arunta seismic line. The abstract discusses mainly the Neoproterozoic and Phanerozoic mineral potential, including implications to U, Cu-Co, Au, Cu-U and energy.

This dataset represents the results of the assessment of the potential for uranium and geothermal energy systems in the southern Northern Territory. Four uranium systems were targeted: 1) sandstone-hosted, 2) uranium-rich iron oxide-copper-gold, 3) unconformity-related, and 4) magmatic-related. These were assessed for using a 2D, GIS-based approach, and utilised a mineral systems framework. In addition to the uranium systems investigated, the potential for hot rock and hot sedimentary aquifer geothermal systems was also assessed. Only the results of the hot rock geothermal assessment are presented here, since the assessment for hot sedimentary aquifer geothermal systems is more qualitative in nature. The assessment for hot rock geothermal systems was undertaken in a 3D environment, with temperatures at depth predicted using the 3D GeoModeller software package.

Significant volumes of Big Lake Suite granodiorite intrude basement in the Cooper Basin region of central Australia. Thick sedimentary sequences in the Cooper and overlying Eromanga Basins provide a thermal blanketing effect resulting in elevated temperatures at depth. 3D geological maps over the region have been produced from geologically constrained 3D inversions of gravity data. These density models delineate regions of low density within the basement that are interpreted to be granitic bodies. A region was extracted from the 3D geological map and used as a test-bed for modelling the temperature, heat flow and geothermal gradients. Temperatures were generated on a discretised version of the model within GeoModeller and were solved by explicit finite difference approximation using a Gauss-Seidel iterative scheme. The thermal properties that matched existing bottom hole temperatures and heat flows measurements were applied to the larger 3D map region. An enhancement of the GeoModeller software is to allow the input thermal properties to be specified as distribution functions. Multiple thermal simulations are carried out from the supplied distributions. Statistical methods are used to yield the probability estimates of the temperature and heat flow, reducing the risk of exploring for heat.

A regional seismic survey in north Queensland, with acquisition paremeters set for deep crustal imaging, show a potential geothermal target beneath about 2 km of sediments. Beneath the sedimentary structure there appears to be an area of low seismic reflection signal from about 1 s to 4 s. Combined with the relatively low gravity signature over this location, this area of low seismic reflection signal could be interpreted as a large granite body, overlain by sediments. This body lies near an area of high crustal temperature and suggests a potential geothermal energy target.

Examination of developing geothermal exploration techniques and a geothermal play systems framework in Australia.