We collected 38 groundwater and two surface water samples in the semi-arid Lake Woods region of the Northern Territory to better understand the hydrogeochemistry of this system, which straddles the Wiso, Tennant Creek and Georgina geological regions. Lake Woods is presently a losing waterbody feeding the underlying groundwater system. The main aquifers comprise mainly carbonate (limestone and dolostone), siliciclastic (sandstone and siltstone) and evaporitic units. The water composition was determined in terms of bulk properties (pH, electrical conductivity, temperature, dissolved oxygen, redox potential), 40 major, minor and trace elements as well as six isotopes (δ18Owater, δ2Hwater, δ13CDIC, δ34SSO4=, δ18OSO4=, 87Sr/86Sr). The groundwater is recharged through infiltration in the catchment from monsoonal rainfall (annual average rainfall ~600 mm) and runoff. It evolves geochemically mainly through evapotranspiration and water–mineral interaction (dissolution of carbonates, silicates, and to a lesser extent sulfates). The two surface waters (one from the main creek feeding the lake, the other from the lake itself) are extraordinarily enriched in 18O and 2H isotopes (δ18O of +10.9 and +16.4 ‰ VSMOW, and δ2H of +41 and +93 ‰ VSMOW, respectively), which is interpreted to reflect evaporation during the dry season (annual average evaporation ~3000 mm) under low humidity conditions (annual average relative humidity ~40 %). This interpretation is supported by modelling results. The potassium (K) relative enrichment (K/Cl mass ratio over 50 times that of sea water) is similar to that observed in salt-lake systems worldwide that are prospective for potash resources. Potassium enrichment is believed to derive partly from dust during atmospheric transport/deposition, but mostly from weathering of K-silicates in the aquifer materials (and possibly underlying formations). Further studies of Australian salt-lake systems are required to reach evidence-based conclusions on their mineral potential for potash, lithium, boron and other low-temperature mineral system commodities such as uranium. <b>Citation:</b> P. de Caritat, E. N. Bastrakov, S. Jaireth, P. M. English, J. D. A. Clarke, T. P. Mernagh, A. S. Wygralak, H. E. Dulfer & J. Trafford (2019) Groundwater geochemistry, hydrogeology and potash mineral potential of the Lake Woods region, Northern Territory, Australia, <i>Australian Journal of Earth Sciences</i>, 66:3, 411-430, DOI: 10.1080/08120099.2018.1543208

The extended abstract describes the geophysical characteristics of the granite dominated geophysical map units of the Yilgarn Craton and the relationship between their deformation and gold mineralisation. Aeromagnetic data are not able to distinguish the five main granite geochemical groups. Gamma-ray spectromatric data provide some distinctin of the geochemical groups but their use is restricted to limited areas of outcrop. Faults host much gold but the majority of these structures are barren and spatial associations have been difficult to establish. Shear zones are irregularly distributed across the craton. Abundant intersecting shear zones, that transect both granite and greenstone, define a 200 km wide, north-trending corridor, with distinctive rhomboid to sigmoidal internal geometry. Greenstones in the corridor are extensively disrupded and strongly aligned with adjacent shear zones. This corridor correlates with the the region of highest gold endowment for the Yilgarn Craton and large deposits are spatially associated with bends and intersections of the shear zones. By contrast, shear zones are sparse in the Yalgoo Dome area in the north west of the Yilgarn Craton. The crustal architecture of this area is dominated by large ovoid bodies of granite. Adjacent greesntones are not regionally alligned, nor particularly disrupted internally, and gold endowment is low. These aparent contrasting structural styles and corresponding differences in gold endowment can be similarly applied to the Superior Province of Canada (Abatibi Belt, abundant intersecting shear zones, strongly aligned greenstone, and high gold endowment) and Australia's Pilbara Craton (few shear zones, oviod granite geometry dominant with little regional alignment of greenstone and low gold endowment).

The Stavely Project is a collaboration between Geoscience Australia and the Geological Survey of Victoria. During 2014 fourteen pre-competitive stratigraphic drill holes were completed in the prospective Stavely region in western Victoria in order to better understand subsurface geology and its potential for a variety of mineral systems. The Stavely region hosts several belts of poorly-exposed Cambrian volcanic and intrusive rocks, visible largely only in magnetic data, which have similarities to those found in modern subduction-related tectonic settings. Mineralisation associated with porphyry Cu-Au and volcanic-hosted massive sulphide mineral systems is known where these rocks are exposed around Mount Stavely and the Black Range. However, despite a history of mineral exploration dating back to the late 1960s, significant economic deposits are yet to be discovered, and the Stavely region remains a greenfields terrane. Given the geological setting and known mineral potential, opportunity exists for the discovery of large mineral systems beneath extensive, but relatively thin, younger cover. The Stavely Project aims to provide the framework for discovery in the Stavely region primarily through the acquisition and delivery of pre-competitive geoscientific data. This includes the completion of pre-competitive stratigraphic drill holes in order to test regional geological interpretations and recover material for detailed lithological, petrophysical, geochemical and geochronological analysis. The results will assist in understanding the mineral systems potential of the Stavely region under cover. This report summarises data collected in the field at the drill sites, either during or immediately following drilling, as part of the Stavely Project, and describes the methods and procedures used. Data presented in this release include drill hole collar information, operational metadata and daily drilling reports, drill core photographs, down-hole surveys, down-hole wireline geophysical logging results, down-hole temperature logging results, down-hole AutoSondeTM gamma data, Lab-at-RigTM X-ray fluorescence data, diamond drill core recovery percentages, and handheld magnetic susceptibility measurements on the drill core.

Deep-seismic reflection data across the Eastern Goldfields Province, northeastern Yilgarn Craton, Western Australia have provided information on the regions crustal architecture and on several of its highly mineralised regions. The 2001 Northeastern Yilgarn Deep Seismic Rflection Survey data has imaged several prominent crustal scaled features, including an eastward thickening of the crust across the northeastern Yilgarn Craton, the subdivision of the crust into three broad layers, the presence of a prominent east dip to the majority of the reflections and the interpretation of three east-dipping crustal-penetrating shear zones. These three east-dipping shear zones are major structures that subdivide the region into four terranes. Raw data for this survey are available on request from clientservices@ga.gov.au

Australian mineral exploration spending in 2005-06 rose by 20.6% to a record $1240.7 million, 36.9% of which was spent on the search for new deposits. Western Australia dominated with 47.6% of Australian mineral exploration spending while South Australia, New South Wales, Victoria and Queensland had record expenditure. Tasmanian spending rose by 172%. Gold remained the main target, but its share of spending was eroded by growth in nickel, copper, iron ore, coal and uranium exploration. Exploration results were announced for a wide range of commodities from across the country including: Mineral sands (Gullivers, South Australia, and Cooljarloo North, Western Australia) Nickel (Saxon, Tasmania) Gold-copper (Tekapo, Northern Territory) Gold (Tandarra, Victoria, and Tropicana, Western Australia) Base metals (Cuttaburra, New South Wales) Copper (Rocklands, Queensland)

Australian mineral exploration spending in 2006-07 rose by 38% to a record $1,714.6 million of which 36% was spent on the search for new deposits. Spending rose in all States and the Northern Territory with South Australia up by 78% to $260.7 million while Western Australia dominated with 49% of Australian mineral exploration spending. The base metal group was the dominant target accounting for 32% of exploration spending overtaking gold (27%) for the first time since 1983. Exploration results were announced for a wide range of commodities from across the country with the most significant being the announcement of a 38% increase in contained copper in the Olympic Dam deposit, South Australia, and of an initial 4 Moz resource in the Tropicana gold deposit, Western Australia.

In 2001, Australia's economic demonstrated resources (EDR) of bauxite, copper, gold, lead, magnesite, ilmenite, zircon, nickel, phosphate, PGM, tantalum, silver, vanadium and zinc increased, while those of black coal, diamonds, iron ore, lithium, manganese ore and uranium decreased. EDR of brown coal was maintained at levels similar to those reported in 2000. The reductions in EDR were due mainly to ongoing high levels of production; with low commodity prices a subsidiary factor. EDR of gold, nickel and mineral sands reached record levels. Gold EDR rose by 4% and was over 80% of total demonstrated resources, this increase in resources continuing the established long-term growth trend for gold. In recent years that trend has continued despite falling exploration expenditure reflecting an increasing trend to concentrate exploration efforts in brownfields regions in response to the sustained period of depressed gold price. Australia, continues to rank as one of the world's leading mineral resource nations. It has the world's largest EDR of lead, mineral sands, nickel, silver, tantalum, uranium and zinc. In addition, its EDR is in the top six worldwide for bauxite, black coal, brown coal, cobalt, copper, gold, iron ore, lithium, manganese ore, rare earth oxides and gem/near gem diamond. Mineral exploration expenditure rose by 1% to $683.3 million in 2000-01, which was the first increase in annual exploration spending since 1996-97. However spending for calendar year 2001, based on the sum of ABS four-quarter figures, was down by $12 million to $664.4 million. Production of many mineral commodities again reached record levels in 2000-01, and overall mine production is projected by ABARE to rise in the five years to 2006-07 with the exception of gold which they forecast will fall by 6%. ABARE have projected a very high growth of some 60% for mine production of nickel in this period. Increases are also forecast for mine production of coal (+17%), copper (4%), lead (3%), zinc (12%), bauxite (17%) and iron ore (19%).

Australia's mineral resources have been sustained at adequate levels, relative to production, through continued exploration at known deposits and successful exploration in greenfield regions. At a number of mines, resources have increased progressively despite mining over an extended period. Increased efficiencies in mining and processing, achieved through application of new technology, have resulted in higher recoveries of minerals from many deposits.

In 1996, Australia's Economic Demonstrated Resources (EDR) of cobalt, gold, nickel, phosphate rock and tantalum increased substantially, while EDR of bauxite, lead, lithium, platinum group metals (PGM), silver and zinc rose slightly. There was a significant reduction in EDR of gem and near gem diamond and industrial diamond due to ongoing high levels of production. Magnesite and tin EDR were also significantly reduced as a result of depletion due to production and reassessment of deposits. EDR of all other commodities remained unchanged or had minor reductions. Australia continues to rank highly as one of the world's leading mineral resource nations. It has the world's largest EDR of bauxite, lead, mineral sands (ilmenite, rutile and zircon), silver, tantalum, uranium and zinc. In addition, its EDR is in the top six worldwide for black coal, brown coal, cobalt, copper, gold, iron ore, lithium, manganese ore, nickel, rare earth oxides, gem and near gem diamond and industrial diamond. Mineral exploration expenditure rose by 7.5% in 1995-96 to $960.2 million from $893.3 million in the previous year. Increases were recorded in all states and the Northern Territory. Gold was again the main target, accounting for 57% of the total expenditure. In 1995-96 mineral resources exports increased to a new record of $34.7 billion (thousand million), a rise of 12.7% over the previous fiscal year. These export earnings comprised 60% of Australia's commodity exports, 45% of merchandise exports and 35% of the country's total exports of goods and services. The Australian Bureau of Agricultural and Resource Economics (ABARE) forecast export earnings to set a further record in 1996-97, rising by nearly 4% to over $36 billion.

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).