Knowledge of the spatial and temporal relationships between fluid flow, the generation of structures, and crustal architecture is essential to understanding a mineral system. In regions dominated by cover, such knowledge leans heavily on interpretation of potential field data. Forward modelling and inversion of cross-sections, based on solid geology maps, provide better than a first approximation but reliability decreases with extrapolation from the sections. Stereo-models of crustal architecture are possible using closely spaced sections but they are more rigorously produced by 3D inversion. Inversion programs derive a physical property distribution that reproduces potential field observations in a manner consistent with a series of model parameters and geological constraints. The inversion techniques used in this study are based on the smooth-model potential field inversion software, MAG3D and GRAV3D, developed at the University of British Columbia?Geophysical Inversion Facility (UBC?GIF). We tuned some of the parameters and modified the methods for use in regional-scale rather than deposit-scale inversions. The volume of crust chosen for study, centred on the Olympic Dam deposit, is 150 kmx ? 150 kmy ? 10 kmz. Because a buffer is required to minimise edge effects, we model a volume of 198 kmx ? 198 kmy ? 18 kmz, discretised into 1 kmx ? 1 kmy ? 0.5 kmz cells. A series of trial inversions were run on a desktop PC with an Intel? Pentium? 4 2.0 GHz processor and 2 GB of RAM. The initial trials were designed to investigate the feasibility of doing regional-scale inversions and to show where development of methods and software support were needed. For tractable computation, it is necessary to split each volume into a number of overlapping tiles that can be processed independently then rejoined. Even so, runs took up to 40 hours. The time elapsed can be substantially reduced if processing is performed as a distributed application across a network with each PC dedicated to a single tile. The inherent non uniqueness of potential field inversion means that, even after some models have been rejected on `geo-logical? grounds, a number of reasonable models will remain. Tests that prove or disprove the models may be devised but actual physical testing may not be practical. However, we can make, probabilistic determinations of the distribution of Fe oxide alteration, which may be used to map likely fluid pathways and as guides to ore. Such predictions are amenable to testing available in exploration programs.

The Tanami region is one of Australia?s premier Proterozoic gold provinces, having already produced ~150 t of gold, and still has high exploration potential. This region contains more than 60 gold occurrences including the Dead Bullock Soak, Groundrush and The Granites gold mines as well as several significant gold prospects (Coyote, Crusade and Kookaburra). The Callie deposit (>5 Moz Au total resource) located in the Dead Bullock Soak goldfield is currently the largest mine in this region. Previous studies of the mineral systems associated with the gold deposits in the Tanami region indicate that they formed over a range of depths and were hosted in both greenstone and sedimentary units. Fluid inclusion studies have shown that the ore-bearing fluids were generally of low to moderate salinity with varying amounts of CO2?N2?CH4. Trapping temperatures ranged from 220 to 430 ?C. In order to determine the extent of these gold mineral systems, we have investigated the chemistry of the fluids in regional quartz veins that outcrop in both the Tanami, Birrindudu and northern Arunta. 40Ar/39Ar dating of veins containing mica was also carried out to determine the timing of the veins with respect to the mineralisation in the Tanami region. Epithermal veins outcrop along the southern margin of the Wiso Basin, the northern Arunta, the western Tanami and in the Birrindudu region. Two populations of fluid inclusions were observed in the epithermal veins: a low salinity fluid (<1 wt. % NaCl eq), and a high salinity fluid (>18 wt. % NaCl eq). No gases were detected in either type of fluid inclusion and both homogenised over the range from 120 to 180 ?C. Regional E-W trending mesothermal quartz veins outcrop in the southern Tanami region and a distinctive zone of ENE trending quartz veins outcrop in the northern Arunta whereas both NW trending and ENE trending veins occur in the Birrindudu region. Two populations of fluid inclusions were also observed in these mesothermal quartz veins. The first contained low salinity fluids with CO2>CH4?(N2?graphite). These inclusions homogenised between 320 and 360 ?C. The second population contained high salinity fluids with no detectable gases and they homogenised between 120 and 230 ?C. 40Ar/39Ar dating of quartz veins containing mica showed a distinct difference in the age of the veins in the Tanami and northern Arunta. Mesothermal veins in the Tanami region had ages ranging from 1700 to 1741 Ma while quartz veins in the northern Arunta gave ages ranging from 1432 to 1518 Ma. This suggests that these vein sets formed from two separate fluid flow events.

Palaeolatitudes for Precambrian Australia were last reported in 1988. A serious limitation at that time was the sparseness of palaeomagnetic data. While the Australian Precambrian still lacks palaeomagnetic data on the whole, two intervals within it have since become much better defined. These are the late Palaeoproterozoic to earliest Mesoproterozoic and late the Mesoproterozoic to middle Neoproterozoic. Improvements to the former resulted from multidisciplinary studies in the 1990s by AGSO to provide a geological framework for mineral exploration in northern Australia; improvements to the latter are largely due a quest led by the University of Western Australia to determine the configuration of the late Proterozoic supercontinent Rodinia. This report incorporates the improvements in data for an update on Australian Precambrian palaeolatitudes.

In June 2010, Geoscience Australia was tasked by the Australian Government Department of Resources, Energy and Tourism to undertake a qualitative mineral resource [1] potential assessment of the Woomera Prohibited Area (WPA) in central South Australia. The assessment was undertaken in collaboration with the Department of Primary Industries and Resources, South Australia (PIRSA). The mineral resource potential assessment determines the deposit types likely to occur within geological frameworks known or interpreted to exist in the WPA. Geologically prospective areas that contain particular types of deposits are identified and ranked low to high potential, and similarly the level of certainty categorised from lowest (A) to highest (D). [1] 'Mineral resource' is used in this report and maps in the sense defined by United States Geological Survey as a concentration of naturally occurring solid, liquid, or gaseous material in such form and amount that economic extraction is currently or potentially feasible.

Legacy product - no abstract available

Legacy product - no abstract available

Australian mineral exploration spending in 2002-03 rose by 14.4% to $732.5, the first significant increase since 1996-97. Global non-ferrous mineral exploration budgets rose 26% to an estimated US$2.4 billion in 2003. Australia's share of reported world budgets was US$339.3 million (15.5%). All States and the Northern Territory recorded increases in mineral exploration activity. Western Australia dominated with $423.6 million, 57.8% of total Australian mineral exploration expenditure in 2002-03. Gold was the major commodity sought with spending of $378.4 million, 51.7% of the total. There were significant increases in iron ore, coal and nickel exploration. Company exploration activities generated a significant number of drill intersections of economic interest, particularly for gold and nickel, in several mineral provinces. A number of junior companies commenced production of nickel and/or have nickel projects at an advanced stage.

The global distribution of mineral deposits in cratons, belts and districts shows that they are not equally and uniformly endowed with metal. Some cratons are highly fertile (e.g. Yilgarn Craton for Archaean greenstone gold and nickel) and there are those which are almost barren (e.g. Archaen greenstone belts in the Pilbara Craton). Within belts the distribution is equally non-uniform. For instance more than 80% of gold resources in the Yilgarn are concentrated in the Kalgoorlie Terrane of the Eastern Goldfields. At a first level the total endowment can be used to compare mineralised belts and districts, however the distribution of deposit sizes in them can provide a second level constraint on their fertility, in particular the nature and intensity of metal accumulation versus metal dispersion. More enigmatic from this point of view are belts and districts in which the total metal endowment is contained in one or two giant and/or super-giant deposits, such as the Broken Hill in New South Wales, Norilsk-Talnakh in Western Siberia, and Olympic Dam in South Australia. These mjaor deposits represent single "bull elephants" in an "elephant country". Cumulative frequency distribution curves of metals of major mineralized cratons, belts and districts are used to compare the nature of their metal endowment. The analysis shows that the curves of "elephant-bearing" belts and districts are remarkably different from those of "average" belts and districts, and that regional and/or district scale geological factors could have played a significant role in controlling metal endowment. A comparison of curves for belts and districts with similar endowment can be used to assess potential for yet to be discovered deposits and to assess their relative size.

The Gawler Craton has been defined as that region of South Australia where Archaean to Mesoproterozoic crystalline basement has undergone no substantial deformation (except minor brittle faulting) since 1450 Ma (Figure 1; Thomson, 1975; Parker, 1993; Daly et al, 1998). The eastern and southeastern boundaries conventionally are defined by the Torrens Hinge Zone (THZ), although Gawler Craton basement that was deformed during the Delamerian Orogeny is known to the east of the THZ (eg Barossa Complex, Peake and Denison Inliers). The southern boundary corresponds to the inboard edge of the continental shelf. The Gawler Craton and the East Antarctic Craton are rifted segments of the Mawson Continent (Fanning et al, 1995). Western, northwestern and northern boundaries of the Gawler Craton are defined by the faulted margins of thick Neoproterozoic and younger basins. As a consequence of the extensive surficial and sedimentary basin cover, the level of understanding of the craton's geology and prospectivity are limited in comparison with most other Australian Archaean and Proterozoic cratons. Application of high-resolution regional aeromagnetic surveying during the mid-1990s (South Australian Exploration Initiative - SAEI), for the first time allowed an integrated interpretation and synthesis of the geology of the craton (Fairclough and Daly, 1995a; Fairclough and Daly, 1995b; Schwarz, 1996). A revised interpretation of the tectonic evolution of the Gawler Craton incorporating SHRIMP U-Pb geochronology, was presented by Daly et al (1998). Three principal orogenies have been proposed: The Sleafordian Orogeny (peak metamorphism at ~2420-2440 Ma), the Kimban Orogeny (KD1-KD2-KD3: 1845-1700 Ma), and the Kararan Orogeny (~1650 Ma and 1565-1540 Ma). It has been suggested that the Kararan Orogeny in the western and northern Gawler Craton represents the continental collision of the 'eastern proto-Yilgarn' and the Mawson Continent (Daly et al, 1998). The geodynamic significance of the Sleafordian and Kimban Orogenies is unclear. Subdivision of the Gawler Craton into tectonic domains has evolved as further information has become available (Figure 1; eg Parker, 1993; Flint and Parker, 1982; Drexel et al, 1993; Teasdale, 1997). In general the definition and nature of the domain boundaries are not well understood - addressing this problem is a key objective of the Gawler Craton Project. The resultant framework will be important for assessing prospectivity because the ore-forming systems are products of crustal-scale processes that may vary between tectonic domains. The contents of this GA Record were written in 2000, and were presented on the Gawler Project website prior to the publication of this GA Record.

Australia's thorium resources currently amount to 452,000tonnes Th of which 364,000tonnes (80.5%) occur in heavy mineral sand deposits, 53,300tonnes (11.7%) in a vein type deposit at Nolans Bore in the Northern Territory and another 35,000tonnes (7.7%) are in an alkaline trachyte plug at Toongi in New South Wales. This distribution of thorium resources differs from the world wide distribution where 31.3% of the resources occur in carbonatites, 24.6% are in placers, 21.4% in vein type deposits and 18.4% in alkaline rocks. This variance is at least partly due to relatively more, although still inadequate, data on thorium resources being generated by the very active heavy mineral sand operations around Australia. Even where thorium analyses have been carried out for other types of deposits that host thorium, such results are not published since thorium is not considered to be economically important. All of Australia's thorium resources occur in multi-commodity deposits, dominantly the heavy mineral sands and in rare earth deposits where the extraction cost would be shared with if not totally supported by the other commodities in the deposit. Because there has been no large-scale demand for thorium, there has been little incentive for companies to assess the cost for the extraction of thorium resources. Hence there is insufficient information to determine how much of Australia's thorium resources are economic for purposes of electricity power generation in thorium nuclear reactors. Geoscience Australia is currently engaged in upgrading its database on thorium resources as part of the five-year Onshore Energy Security Program and Australia's figures on its thorium resources will be refined as a result of this work. Because of limited demand, there has been very little exploration for thorium in Australia. As part of its five year Onshore Energy Security Program, Geoscience Australia is in process of upgrading its continent wide airborne radiometric coverage and is conducting a low density geochemical sampling program across the continent. These programs will help to develop a better understanding of the geological and geochemical environment of thorium in Australia and provide basic pre-competitive data to reduce risk the level of risk for the mineral exploration industry. Assessment of thorium resources by the minerals industry in the future will depend upon the development of commercial-scale thorium nuclear reactors and the resulting demand for thorium resources.