Uranium mineralization at Coronation Hill is associated with rhyolitic rocks of Upper Proterozoic and sediments of Lower Proterozoic Age. The mineralization at and near the surface is in the form of Autunite and Torbernite; it occurs in a zone of strong fracturing, which effects rocks of both Lower and Upper Proterozoic age. Rubble and soil covers most of the area of interest at Coronation Hill and openings available to date do not allow a full appreciation of the geology of the prospect. A preliminary programme of diamond drilling is recommended to test and prospect and further testing should be guided by such information as is obtained from this drilling. The discovery of uranium mineralization in volcanic rocks of Upper Proterozoic age at Coronation Hill opens up an entirely new province for exploration for uranium in the Katherine-Darwin region of the Northern Territory. The linear belt of fracturing, the South Alligator Fault Zone, on which the Coronation Hill is situated, suggests an obvious zone to which future prospecting effort should be guided.

Sediments of the Brock's Creek Group and of the Phillips Creek Formation, and volcanics of the Edith River Formation were prospected with carborne radiometric equipment. A comparatively high background count was recorded in the Edith River Volcanics, but no significant radiometric anomaly was found. A geological party prospected ten shear zones south east of the Edith Siding, including a cupriferous one, and a strongly fractured belt near the granite contact. No radiometric anomaly was found. Future prospecting should be directed towards major faults within the sediments.

Gold deposits in the Archaean Eastern Goldfields Province in Western Australia were deposited in greenstone supracrustal rocks by fluids migrating up crustal scale fault zones. Regional ENE-WSW D2 shortening of the supracrustals was delaminated from lower crustal shortening at a regional sub-horizontal detachment surface below the base of the greenstones. Major gold deposits lie close to D3 strike slip faults that extend through the detachment surface and into the middle to lower crust. The detachment originally formed at a depth corresponding to the brittle/ductile transition. In orogenic systems the brittle/ductile transition correlates with a low permeability pressure seal separating hydrostatic fluid pressure gradients in the upper crust from suprahydrostatic fluid pressure gradients in the lower crust. Fluid pressures near the base of the low permeability pressure-seal can intermittently exceed lithostatic pressures, leading to tensile strength failure and fluid filled extension fractures. In orogens, the extension fractures will be sub-horizontal, have poor vertical connectivity and become fluids reservoirs. This would create an ideal depth to nucleate a regional detachment surface in a deforming crust. Seismic bright spots at ~6s TWT in Tibet and the western United States are probable examples. If the low permeability pressure seal is subsequently broken by a through going fault, the fluids will be drained into the upper crust. Large, deeply penetrating faults are therefore ideal for focussing fluid flow into the upper crust.

Y4 Presentation of introduction to Targeting and the terrane-scale targeting (presented to sponsors at the final PDT Meeting in Kalgoorie May 2007)

Initial 'straw man' used in the targeting exercise and developed from earlier Y4 (PDT) Meeting in May 2007

Australian Proterozoic Mineralising events on Australian Proterozoic Regions base, 1:4 000 000 July 2007 Version

<p>In February 2009, Geoscience Australia released a new national radiometric map and dataset. This improved radiometric map, shows the distribution of potassium (K), uranium (U) and thorium (Th) at the Earth's surface as measured using the airborne gamma-ray spectrometric method. The gridded data that underpin the map cover over 80 % of the Australian continent at 100m spatial resolution. These data were calibrated to be consistent with an Australian radioelement datum based on an Australia wide airborne geophysical survey (AWAGS2) completed in 2008, which was conducted under the Australian Government funded Onshore Energy Security Initiative. AWAGS provides the baseline for stitching and levelling of all publicly available airborne radiometric (and magnetic) surveys across Australia, which are of a range of ages and qualities, and for future airborne surveys. The new grids of K, eTh and eU can be used to reliably compare the radiometric signatures observed over different parts of Australia, enabling the assessment of key mineralogical and geochemical properties of bedrock and regolith materials from different geological provinces and regions across the continent. These data support a range of different applications including exploration, geological mapping, geomorphological studies and environmental mapping. </p> <p>Presented at AusIMM Uranium Conference, Darwin, 10 June 2009.</p>

Plans for the National Geochemical Survey of Australia were presented to the geoscience agencies of all States and the Northern Territory in early 2007. The presentation entitled National Geochemical Survey of Australia: outline of a new proposal was given to: Primary Industries and Resources South Australia in Adelaide on 20 February 2007 Geological Survey of Western Australia in Perth on 21 February 2007 New South Wales Department of Primary Industries in Maitland on 29 March 2007 Geological Survey of Queensland in Brisbane on 2 May 2007 Northern Territory Geological Survey in Darwin on 3 May 2007 Minerals Resources Tasmania in Hobart on 16 May 2007 GeoScience Victoria in Melbourne on 17 May 2007

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.