The Treasure Mine, Hatches Creek, is believed to have been discovered in 1914 and has been one of the most consistent producers of wolfram to the present time. This report gives an account of the economic geology of the mine. The ore type, reefs and workings, ore localization, and ore reserves are described.

The Late Archaean granite-greenstone terranes of the Yilgarn Craton WA are the host to Australia's premier world-class orogenic Au deposits. The Eastern Goldfields Superterrane (EGST) within this region hosts the majority of Au deposits and is therefore data rich, with high-resolution gravity, magnetics, geological and geochemical maps and databases, augmented with a number of high-quality deep seismic reflection profiles, teleseismic and magnetotelluric studies. Research within Geoscience Australia and the Predictive Mineral Discovery Cooperative Research Centre (pmd*CRC) have integrated these data into a set of new 3D maps at a range of scales. Integration of these data in 3D space has enabled greater understanding of the giant Au mineral systems. At the craton scale a tomographic survey was deployed to investigate whether anomalous crustal and/or upper mantle velocities exist beneath the highly mineralised EGST compared to "normal" velocities beneath barren regions in the Yilgarn Craton as a whole. The resulting velocity data were spatially represented in 3D using Gocad, enabling spatial links to be drawn between dramatic velocity variations in the tomographic data and zones of mineralisation in the upper crust. At the crustal/upper mantle scale, 2D seismic reflection lines throughout the EGST have imaged crustal penetrating shear zones that are often spatially coincident with mineralised corridors. Multiple 2D seismic reflection profiles, combined with geological and potential field data, have enabled the sub-surface geometries of faults to be constructed in three dimensions, providing insight into potential fluid pathways. A 130 km long magnetotellurics survey located along the EGF01 seismic line was also used to explore the relationship between seismic architecture and the crustal/upper mantle-scale conductivity distribution. At the camp-scale, 3D technologies have greatly improved our ability to compare complex relationships between spatially referenced 2D and 3D data, leading to improved targeting. The construction and display of the 3D distribution of lithological units and complex fault arrays, as surfaces and solid volumes, has enabled the 3D geology of a region to be statistically analysed in a quantitative way that is not possible using conventional techniques. Mine- to camp-scale 3D faults, lithologies and alteration assemblages are used to define preferential zones of fluid flow and Au deposition. This process involves detailed structural analysis of mineralisation at mine-scale to determine stress vectors during mineralisation, combined with numerical modelling of preferentially orientated structures. Favourably orientated faults calibrated with known mineralisation and alteration assemblages provide a framework to statistically analyse the relationship between structural architecture, alteration signatures and mineral deposition. 3D maps provide a tool to analyse data at a range of scales and better integrate a wide range of datasets. These technologies enable spatial and temporal relationships to be compared in a more quantitative way and also provide a 3D interpretation of geology that can be statistically analysed for predictive mineral discovery.

The poster/panel summarises result of preliminary fluid flow and chemical modelling in the Frome Embayment

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.

Fluid inclusion studies of the major deposits and prospects in the Tanami region indicate that they formed over a range of temperatures and depths. Gold mineralisation is structurally controlled with the highest grades occurring in brittle, dilational structures or at the intersection of quartz veins and anticlines. Mineralisation occurs in a number of different rock assemblages including amphibolite facies sediments, greenschist facies sediments, intercalated units of basalt and sediments, and dolerite intrusives, but in all cases there is a close relationship between mineralisation and carbonaceous shales or iron-rich lithologies. The ore-bearing fluids appear to range in composition but are generally moderate to low-salinity fluids (<13 wt% NaCl eq), which contain CO2 to a greater or lesser extent. The different gas compositions of the fluids result from fluid-rock interaction leading to generation of CH4 or N2 depending on whether the fluids have interacted with mafic or sedimentary sequences. Microthermometric and laser Raman microprobe data indicate that the Groundrush deposit formed at the greatest temperatures and depths (260 ? 430 ?C and up to 11 km), from moderate salinity fluids (?13.9 wt.% NaCl eq.) that were enriched in CH4 ? CO2. The Granites deposit formed at temperatures ranging from 220 ? 312 ?C and depths between 2.3 and 9.8 km. The ore-fluids contained CO2 ? N2 ? CH4 and were of low to moderate salinity (0 ? 14 wt.% NaCl eq.). The Coyote prospect formed over the range 290 ? 360 ?C and at depths between 3.4 and 7.5 km. This deposit contained CO2-rich inclusion (some with graphite crystals), CH4-rich inclusions (also some with graphite crystals), and CO2 ? N2-bearing inclusions, all with salinities below 6.7 wt.% NaCl eq. The Callie deposit formed at temperatures ranging from 254 ? 326 ?C and depths between 2.3 and 6.0 km. The ore-forming fluids contained CO2 ? N2 and had salinities ?13 wt.% NaCl eq., but there is also evidence for isothermal mixing with higher salinity fluids. Deposits in the region of the Tanami Gold Mine formed at temperatures ranging from 260 ? 380 ?C and depths between 1.5 and 5.6 km. Low to moderate salinity (?13 wt.% NaCl eq.),CO2-bearing inclusions were only observed in quartz veins from 2 of the open-cut pits but these inclusions are believed to represent the mineralising fluids in this region. The quartz veins from these deposits typically contain ubiquitous 2-phase, aqueous inclusions with evidence for isothermal mixing between high- and low-salinity fluids at temperatures between 100 and 200 ?C. Hydrogen, oxygen, and carbon isotopic data from fluid inclusions and mineralised quartz veins indicate that the source of the mineralising fluids was either a metamorphic or mixed magmatic/metamorphic fluid. However, as most deposits in the Tanami region appear to post-date the main period of magmatic activity, a metamorphic origin for the mineralising fluids appears the most likely. Gold mineralisation in the Tanami region resulted from fluid/rock interaction and reduction of the ore-bearing fluids by Fe-rich rocks or graphitic sediments. However, at higher crustal levels, boiling/effervescence due to pressure fluctuations may have enhanced gold deposition. There is also evidence for fluid mixing which, particularly for the deposits of the Tanami Gold Mine, occurs at lower temperatures than those estimated for mineralisation, indicating that it is a late stage process with little effect on the main stage of mineralisation.

Legacy product - no abstract available

The Ranger deposit is one of Australia's largest known uranium resources, with current open pit mining of the No. 3 orebody and a total resource of 109,600 tonnes of U3O8 grading 0.08% at this orebody (ERA, January 2011). This unconformity-related deposit is hosted by Paleoproterozoic metasedimentary rocks of the Cahill Formation which is unconformably overlain by sandstones of the Kombolgie Formation. A maximum depositional age of ~1818 Ma is inferred for the sandstones, based on the presence of the Nabarlek Granite of this age in the basement beneath the Kombolgie Formation. Most mineralisation occurs within a largely stratabound shear and breccia zone and is associated with intense proximal chlorite and distal white mica alteration. The Kombolgie Formation is weakly deformed, faulted and weakly chloritised above the mineralisation.

Legacy product - no abstract available

As part of the North Pilbara NGMA Project, AGSO (now Geoscience Australia), together with Newcastle University and the Geological Survey of Western Australia (GSWA), have been conducting a research program to document the geological setting, characteristics and genesis of Au deposits of the North Pilbara Terrane. This record summarises some results of this research program. This research has concentrated on turbidite-hosted lode Au deposits in the Indee and Nullagine areas as well as basalt and ultramafic-hosted deposits in the Mt York-Lynas Find area. In addition to these areas, AGSO's research also concentrated on epithermal deposits in the Indee area, and less detailed studies were undertaken on lode Au deposits at Gold Show Hill and Klondyke. This research program was designed to complement recent (e.g., Neumayr et al. [1993; 1998] on the York deposits and Zegers [1996] on the Bamboo Creek deposits) and ongoing (e.g., D. Baker, University of Newcastle] at Mt York-Lynas Find) programs conducted at the other institutions. This Pilbara Gold Record is supported by an extensive GIS dataset, providing many new digital data sets, including a number of variations of the magnetics, gravity, and gamma-ray spectrometry. A solid geology map, and derivative maps, mineral deposits, geological events, and Landsat 5-TM provide additional views. This data set complements the 1:1.5 Million scale colour atlas (Blewett et al., 2000).

A reconnaissance survey of the eastern half of the Canberra 4-mile sheet was made during the period January - February 1952. The area mapped may be arbitrarily divided into two sections: the western section includes the eastern halves of the Canberra, Michelago, and Bredbo 1-mile sheets, and the eastern section comprises four 1-mile sheets - Lake Bathurst, Braidwood, Araluen and Bendethera. Belts of strongly folded Ordovician, Silurian and Devonian strata, with associated elongate masses of granite rocks, were encountered; they trend gradually northwards. Graptolites collected from Ordovician strata provide means to date these rocks accurately, and further study of the corals collected from Silurian limestones will similarly permit precise dating. Three fossil localities were found in the Devonian strata, but the brachiopods collected, although well-preserved and representative of many genera, do not permit precise stratigraphical placing without more intensive examination. Outcrops are generally very good in all parts except the Lake Bathurst area, where an extensive cover of Tertiary and later deposits obscures the Palaeozoic rocks.