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

This service has been created specifically for display in the National Map and the chosen symbology may not suit other mapping applications. The Australian Topographic web map service is seamless national dataset coverage for the whole of Australia. These data are best suited to graphical applications. These data may vary greatly in quality depending on the method of capture and digitising specifications in place at the time of capture. The web map service portrays detailed graphic representation of features that appear on the Earth's surface. These features include the administration boundaries from the Geoscience Australia 250K Topographic Data, including state forest and reserves.

<div>Lithospheric structure and composition have direct relevance for our understanding of mineral prospectivity. Aspects of the lithosphere can be imaged using geophysical inversion or analysed from exhumed samples at the surface of the Earth, but it is a challenge to ensure consistency between competing models and datasets. The LitMod platform provides a probabilistic inversion framework that uses geology as the fabric to unify multiple geophysical techniques and incorporates a priori geochemical information. Here, we present results from the application of LitMod to the Australian continent. The rasters summarise the results and performance of a Markov-chain Monte Carlo sampling from the posterior model space. Release KY22 is developed using the primary-mode Rayleigh phase velocity grids of Yoshizawa (2014).</div><div><br></div><div>Geoscience Australia's Exploring for the Future program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia's geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia's transition to a low emissions economy, strong resources and agriculture sectors, and economic opportunities and social benefits for Australia's regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government.</div>

This service contains the NATMAP 1:250,000 scale maps, from the NATMAP Digital Maps 2008 DVD. The large scale single mosaic map covers the entire continent, and is based on the Geocentric Datum of Australia 1994 (GDA94) geographic projection. The maps have been revised using a variety of data sources, including SPOT and Landsat satellite imagery, other government agency information and data supplied by private companies and individuals. The original DVD was produced by Geoscience Australia's National Mapping Division and its predecessor, the Australian Surveying and Land Information Group (AUSLIG).

This service contains the NATMAP 1:250,000 scale maps, from the NATMAP Digital Maps 2008 DVD. The large scale single mosaic map covers the entire continent, and is based on the Geocentric Datum of Australia 1994 (GDA94) geographic projection. The maps have been revised using a variety of data sources, including SPOT and Landsat satellite imagery, other government agency information and data supplied by private companies and individuals. The original DVD was produced by Geoscience Australia's National Mapping Division and its predecessor, the Australian Surveying and Land Information Group (AUSLIG).

This service provides Australian surface hydrology, including natural and man-made features such as water courses (including directional flow paths), lakes, dams and other water bodies. The information was derived from the Surface Hydrology database, with a nominal scale of 1:250,000. The National Basins and Catchments are a national topographic representation of drainage areas across the landscape. Each basin is made up of a number of catchments depending on the features of the landscape. This service shows the relationship between catchments and basins. The service contains layer scale dependencies.

This service shows the Principal Hydrogeological Divisions of Australia which was produced from the 1:5,000,000 scale Hydrogeology of Australia map (Jacobsen and Lau, 1987).

This service contains the NATMAP 1:250,000 scale maps, from the NATMAP Digital Maps 2008 DVD. The large scale single mosaic map covers the entire continent, and is based on the Geocentric Datum of Australia 1994 (GDA94) geographic projection. The maps have been revised using a variety of data sources, including SPOT and Landsat satellite imagery, other government agency information and data supplied by private companies and individuals. The original DVD was produced by Geoscience Australia's National Mapping Division and its predecessor, the Australian Surveying and Land Information Group (AUSLIG).

<div>Magmatic arcs represent a critical source of modern civilisation’s mineral wealth, with their importance only enhanced by the ongoing global transition to a low-carbon society. The ~830-495 Ma Delamerian Orogen, formed at Australia’s eastern cratonic margin, represents rocks ascribed to rift/passive-margin, convergent margin arc, orogenic, and post-orogenic settings. However, poor exposure has limited exploration activity across much of the orogen, despite demonstrated potential for numerous mineral systems. To address this issue, an orogen-wide zircon Hf-O isotope and trace element survey was performed on 55 magmatic samples to constrain the crustal architecture, evolution, and fertility of the Delamerian Orogen, and in turn map parameters that can be used as a guide to mineral potential. These new data define two broad magmatic episodes at: (1) ~585-480 Ma, related to rift/passive margin, convergent arc, orogenic, and post-orogenic activity (Delamerian Cycle); and (2) magmatism associated with the ~490-320 Ma Lachlan Orogen, with peaks at ~420 Ma (onshore, Tabberabberan Cycle) and ~370 Ma (western Tasmania). Isotopic and geochemical mapping of these events show that the ~585-480 Ma Delamerian Cycle has significant orogen-wide variation in magmatic Hf-O isotopes and oxidation-state, suggesting a spatial variation in the occurrence and type of potential mineral systems. The ~420 Ma magmatic event involved predominantly mantle-like Hf-O and oxidised magmatism, whilst the ~370 Ma magmatism shows opposing features. In general, The potential to host Cu-Au porphyry and VMS mineralisation (e.g., Stavely, Koonenberry) is present, but restricted, whereas signatures favourable for Sn-W granite-hosted systems (e.g., Tasmania), are more common. These new data constrain time-space variations in magma composition that provide a valuable geological framework for mineral system fertility assessments across the Delamerian Orogen. Furthermore, these data and associated maps can used to assess time-space mineral potential and facilitate more effective exploration targeting in this covered region.</div> <b>Citation:</b> Mole, D., Bodorkos, S., Gilmore, P.J., Fraser, G., Jagodzinski, E.A., Cheng, Y., Clark, A.D., Doublier, M., Waltenberg, K., Stern, R.A., Evans, N.J., 2023. Architecture, evolution and fertility of the Delamerian Orogen: Insights from zircon. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, <a href+"https://dx.doi.org/10.26186/148981">https://dx.doi.org/10.26186/148981</a>