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

With the increasing need to extend mineral exploration under cover, new approaches are required to better understand concealed geology, and to narrow the mineral prospectivity search-space. Hydrogeochemistry is a non-invasive exploration technique based on the premise that groundwater interacting with a deposit or supergene alteration can cause anomalous elemental and isotopic signatures down-gradient. Water chemistry can reflect mineralisation directly, but can also reveal other key components of a mineral system, including fluid-flow pathways (e.g. fault/fracture zones), evidence for mineral system traps (e.g. evaporites, shales), or metal sources (e.g. mafic rocks). The Northern Australia Hydrogeochemical Survey (NAHS) was a multiyear regional groundwater sampling program that aimed to understand the regional mineral potential within the Tennant Creek to Mt Isa area (Schroder et al. 2020). This presentation will explore the application of NAHS for investigating mineral potential of a region and present a workflow for establishing spatial or lithological baselines to evaluate hydrogeochemical anomalies. The Georgina Basin is well known for its phosphate potential, with several >1Mt deposits discovered in recent years such as Amaroo and Wonarah; however, the basin has been largely unmapped in terms of phosphate distribution under cover. This work focuses on a subset of 160 NAHS samples collected within two predominant aquifers of the Cambrian Georgina Basin (and time equivalents in the Wiso Basin). This focus restricts us to samples which experience a similar climate, recharge conditions, and aquifer compositions, reducing the hydrogeochemical variation that can mask intra-aquifer anomalies. Elevated dissolved phosphate, PO43- (normalised to HCO3- or Cl-), is observed in the groundwater on the eastern margin of the Georgina Basin. This region is known for Cambrian phosphorite deposits, with sampled bores proximal to a number of near-surface Georgina Basin phosphate deposits. We tested trace element (i.e. U, V and REEs) concentrations as a tool for discriminating phosphate dissolution, however at this regional scale of sampling, possible anomalies were only seen in few bores, thus it is difficult to conclude if this is a consistent relationship robust enough for exploration. More promising may be the use of REE ratios as another indicator of proximity to a phosphate deposit. Emsbo et al. (2015) note that REE compositions of phosphates are relatively consistent globally within a geological period. REE spidergrams of the high PO43- waters are similar to the average REE spidergram of Cambrian phosphates, which contrasts to the REE spidergram of low PO43- groundwaters. Cerium and Europium deviations make this relationship less diagnostic, thus we explore a series of REE ratios (i.e. Er/Dy, Er/Gd, Sm/Nd) for characterising PO43- relationships in groundwater, and use this to suggest other regions of the Georgina Basin with potential for subsurface phosphate deposits. References: Emsbo, P., McLaughlin, P.I., Breit, et al., 2015. Rare earth elements in sedimentary phosphate deposits: solution to the global REE crisis? Gondwana Research, 27(2), 776-785. Schroder, I.F., Caritat, P. de, Wallace, L., et al., 2020. Northern Australia Hydrogeochemical Survey: Final Data Release and Hydrogeochemical Atlas for EFTF. Geoscience Australia, Canberra. http://dx.doi.org/10.11636/Record.2020.015 Abstract presented at the 2021 Australian Earth Sciences Convention (AESC)

This report was compiled and written to summarise the four-year Palaeovalley Groundwater Project which was led by Geoscience Australia from 2008 to 2012. This project was funded by the National Water Commission's Raising National Water Standards Program, and was supported through collaboration with jurisdictional governments in Western Australia, South Australia and the Northern Territory. The summary report was published under the National Water Commission's 'Waterlines' series. This document is supported by related publications such as the palaeovalley groundwater literature review, the WASANT Palaeovalley Map and associated datasets, and four stand-alone GA Records that outline the detailed work undertaken at several palaeovalley demonstration sites in WA, SA and the NT. Palaeovalley aquifers are relied upon in outback Australia by many groundwater users and help underpin the economic, social and environmental fabric of this vast region. ‘Water for Australia’s arid zone – Identifying and assessing Australia’s palaeovalley groundwater resources’ (the Palaeovalley Groundwater Project) investigated palaeovalleys across arid and semi-arid parts of Western Australia (WA), South Australia (SA) and the Northern Territory (NT). The project aimed to (a) generate new information about palaeovalley aquifers, (b) improve our understanding of palaeovalley groundwater resources, and (c) evaluate methods available to identify and assess these systems.

A comprehensive compilation of rock, regolith and groundwater geochemistry across the Curnamona Province and overlying basins. This product is part of the Curnamona Geochemistry module of GA's Exploring for the Future program, which is seeking to understand geochemical baselines within the Curnamona Province to support mineral exploration under cover. Data is sourced from GA, CSIRO and state databases, and run through a quality control process to address common database issues (such as unit errors). The data has been separated by sample type and migrated into a standard data structure to make the data internally consistent. A central source for cleaned geochemical data in the same data format is a valuable resource for further research and exploration in the region.

<div>As part of Geoscience Australia’s Exploring for the Future program, the Curnamona Geochemistry project is producing a comprehensive compilation of geochemical data from the Broken Hill region, encompassing rock, regolith and groundwater. As part of these efforts, geochemical data has been compiled, cleaned and standardised to enable more seamless interpretation and exploration of geochemical anomalies. This project improves the quality, accessibility and volume of geochemical data across the Curnamona region and supports our ongoing efforts to define regional geochemical baselines.</div> This presentation was given to the 2022 Geological Survey of South Australia (GSSA) Discovery Day 1 December (https://www.energymining.sa.gov.au/home/events-and-initiatives/discovery-day)

<div>A powerpoint presentation given by Ivan Schroder at Uncover Curnamona 2022. The presentation covers the activities and upcoming products of the Curnamona Geochemistry module (within the Darling Curnamona Delamerian Project of the Exploring for the Future Program)</div>

<div>The project ‘Assessing the Status of Groundwater in the Great Artesian Basin’ assessed existing and new geoscientific data and technologies, including satellite data, to improve our understanding of the groundwater system and water balance in the GAB. An updated classification of GAB aquifers and aquitards was produced, linking the hydrostratigraphic classification used in Queensland (Surat Basin) with that used in South Australia (western Eromanga Basin). This revised hydrogeological framework was produced at the whole-of-GAB scale, through the development and application of an integrated basin analysis workflow, producing an updated whole-of-GAB stratigraphic interpretation that is consistent across jurisdictional boundaries. Groundwater recharge rates were estimated across eastern GAB recharge area using environmental tracers and an improved method that integrates chloride concentration in bores, rainfall, soil clay content, vegetation type and surficial geology. Significant revisions were made to the geometry and heterogeneity of the groundwater recharge beds, by acquiring, inverting and interpreting regional scale airborne electromagnetic (AEM) geophysical data, identifying potential connectivity between aquifers, possible structural controls on groundwater flow paths and plausible groundwater sources of spring discharge. A whole-of-GAB water balance was developed to compare inflows and outflows to the main regional aquifer groups. While the whole-of-GAB and sub-basin water balances provide basin-wide perspectives of the groundwater resources, they also highlight the high uncertainties in the estimates of key water balance components that need to be considered for groundwater resource management. Assessment of satellite monitoring data from Gravity Recovery and Climate Experiment (GRACE) and Interferometric Synthetic Aperture Radar (InSAR) shows promise for remote monitoring of groundwater levels at a whole-of-GAB scale in the future to augment existing monitoring networks. This presentation was given at the 2022 Australasian Groundwater Conference 21-23 November (https://www.aig.org.au/events/australasian-groundwater-conference-2022/)

The stabilities of uranyl-carbonate and uranyl-hydroxide aqueous complexes were experimentally determined at temperatures ranging from 25 to 125 °C using in situ UV–vis and Raman spectroscopic techniques. Combined with earlier determinations of the stability of chloride, sulfate, and hydroxide complexes at temperatures up to 250 °C, these data permit to create a consolidated dataset suitable for modeling of U(VI) mobilization in natural systems. The parameters of the Modified Ryzhenko-Bryzgalin and the Helgeson-Kirkham-Flowers (HKF) Equations of State (EoS) were derived based on this dataset and used for thermodynamic modeling different scenarios of U(VI) mobilization. These models suggest that at conditions relevant to natural systems, carbonate-mediated transport of U(VI) is likely suppressed by the high stability of solid UO2(OH)2 and Na2U2O7. In contrast, sulfate-mediated mobilization mechanisms are highly efficient at acidic and near-neutral pH conditions and can lead to effective hydrothermal mobilization of U(VI). <b>Citation:</b> A. Migdisov, E. Bastrakov, C. Alcorn, M. Reece, H. Boukhalfa, F.A. Capporuscio, C. Jove-Colon, A spectroscopic study of the stability of uranyl-carbonate complexes at 25–150 °C and re-visiting the data available for uranyl-chloride, uranyl-sulfate, and uranyl-hydroxide species, <i>Geochimica et Cosmochimica Acta</i>, 2024, ISSN 0016-7037, https://doi.org/10.1016/j.gca.2024.04.023.

The Exploring for the Future program Showcase 2024 was held on 13-16 August 2024. Day 4 - 16th August talks included: <b>Session 1 – Deep Dives into the Delamerian</b> <a href="https://youtu.be/09knAwPnD7s?si=acdu6pQgIj7DNlnj">Scaffold to success: An overview of the Delamerian Orogen, and its crustal and lithospheric architecture</a> - Chris Lewis <a href="https://youtu.be/5GQC5f5IkWc?si=rLPqxoZFkxGAEPEf">Only time will tell: Crustal development of the Delamerian Orogen in space and time</a> - David Mole <a href="https://youtu.be/PhdIYE49eqU?si=d7acyv5rbTW_wTiO">Is it a big deal? New mineral potential insights of the Delamerian Orogen</a> - Dr Yanbo Cheng <b>Session 2 – Deep dives into Birrindudu, West Musgrave and South Nicholson–Georgina regions</b> <a href="https://youtu.be/DEbkcgqwLE8?si=sBKGaMTq_mheURib">Northwest Northern Territory Seismic Survey: Resource studies and results</a> - Paul Henson <a href="https://youtu.be/k9vwBa1fM9E?si=VOG19nBC1DAk-jGH">Tracing Ancient Rivers: A hydrogeological investigation of the West Musgrave Region</a> - Joshua Lester <a href="https://youtu.be/Du1JANovz8M?si=1XEOF87gxhSP9UF3">Water's journey: Understanding groundwater dynamics in the South Nicholson and Georgina basins, NT and QLD </a>- Dr Prachi Dixon-Jain <b>Session 3 – Groundwater systems of the Curnamona and upper Darling-Baaka River</b> <a href="https://youtu.be/nU8dpekmEHQ?si=WygIzefKNzsU4gUA">Groundwater systems of the upper Darling-Baaka floodplain: An integrated assessment</a> - Dr Sarah Buckerfield <a href="https://youtu.be/AKOhuDEPxIA?si=ebradAT6EBwHhPQ_">Potential for a Managed Aquifer Recharge Scheme in the upper Darling-Baaka floodplain: Wilcannia region</a> - Dr Kok Piang Tan <a href="https://youtu.be/epUdD8ax2FQ?si=_aMO_e_ZDZESgLOR">Aquifer alchemy: Decoding mineral clues in the Curnamona region</a> - Ivan Schroder Exploring for the Future: Final reflection – Karol Czarnota Resourcing Australia’s Prosperity – Andrew Heap View or download the <a href="https://dx.doi.org/10.26186/149800">Exploring for the Future - An overview of Australia’s transformational geoscience program</a> publication. View or download the <a href="https://dx.doi.org/10.26186/149743">Exploring for the Future - Australia's transformational geoscience program</a> publication. You can access full session and Q&A recordings from YouTube here: 2024 Showcase Day 4 - Session 1 - <a href="https://www.youtube.com/watch?v=4nuIQsl71cY">Deep Dives into the Delamerian</a> 2024 Showcase Day 4 - Session 2 - <a href="https://www.youtube.com/watch?v=9N3dIZRAcHk">Deep dives into Birrindudu, West Musgrave and South Nicholson–Georgina regions</a> 2024 Showcase Day 4 - Session 3 - <a href="https://www.youtube.com/watch?v=_ddvLAnUdOI">Groundwater systems of the Curnamona and upper Darling-Baaka River</a>

<div><strong>Output Type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short Abstract: </strong>Groundwater geochemistry is an important and often under-appreciated medium to understand geology below surface and is a valuable tool as part of a regional mineral exploration program. This study presents an assessment of hydrogeochemical results from the Curnamona and Mundi region with respect to their insights into mineral prospectivity and characterisation of groundwater baselines. The work is a collaboration with the Mineral Exploration Cooperative Research Centre (MinEx CRC), the Geological Survey of New South Wales and the Geological Survey of South Australia as part of Geoscience Australia’s Exploring for the Future program. It combines new and legacy groundwater chemistry from 297 samples to identify multiple elevated multi-element anomalies (Ag, Pb, Cd) and signatures of sulfide mineralisation (d34S and sulfur excess), which are interpreted as potential features from subsurface Broken Hill Type mineralisation (Pb-Zn-Ag). Additional multi-element anomalies (Cu, Mo, Co, Au) may be attributable to Cu-Au, Cu-Mo and Au mineralisation. We then apply hierarchical cluster analysis to understand sample hydrostratigraphy and characterise robust hydrogeochemical baselines for the major aquifer systems in the region. This reveals that the majority of anomalies are restricted to groundwaters derived from basement fractured rock aquifer systems, with a couple anomalies observed in the Lake Eyre Basin cover, which helps narrow the search-space for future groundwater-based mineral exploration in this region (to prioritise these aquifers and anomalies). In addition, we demonstrate the capability of these local hydrogeochemical baselines to support more sensitive resolution of hydrogeochemical anomalies relating to mineralisation, as well as reveal hydrogeological processes such as mixing.</div><div><br></div><div><strong>Citation: </strong>Reid, N., Schroder, I., Thorne, R., Folkes, C., Hore, S., Eastlake, M., Petts, A., Evans, T., Fabris, A., Pinchand, T., Henne A., & Palombi, B.R., 2024. Hydrogeochemistry of the Curnamona and Mundi region. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts. Geoscience Australia, Canberra. https://doi.org/10.26186/149509</div>