Geoscience Australia’s regional assessments and basin inventories are investigating Australia’s groundwater systems to improve knowledge of the nation’s groundwater potential under the Exploring for the Future (EFTF) Program and Geoscience Australia’s Strategy 2028. Where applicable, integrated basin analysis workflows are being used to build geological architecture advancing our understanding of hydrostratigraphic units and tie them to a nationally consistent chronostratigraphic framework. Here we focus on the Great Artesian Basin (GAB) and overlying Lake Eyre Basin (LEB), where groundwater is vital for pastoral, agricultural and extractive industries, community water supplies, as well as supporting indigenous cultural values and sustaining a range of groundwater dependent ecosystems such as springs and vegetation communities. Geoscience Australia continued to revise the chronostratigraphic framework and hydrostratigraphy for the GAB infilling key data and knowledge gaps from previous compilations. In collaboration with Commonwealth and State government agencies, we compiled and standardised thousands of boreholes, stratigraphic picks, 2D seismic and airborne electromagnetic data across the GAB. We undertook a detailed stratigraphic review on hundreds of key boreholes with geophysical logs to construct consistent regional transects across the GAB and LEB, using geological time constraints from hundreds of boreholes with existing and newly interpreted biostratigraphic data. We infilled the stratigraphic correlations along key transects across Queensland, New South Wales, South Australia and Northern Territory borders to refine nomenclature and stratigraphic relationships between the Surat, Eromanga and Carpentaria basins, improving chronostratigraphic understanding within the Jurassic to Cretaceous units. We extended the GAB geological framework to the overlying LEB to better resolve the Cenozoic stratigraphy and potential hydrogeological connectivity. New data and information fill gaps and refine the previous 3D hydrogeological model of the entire GAB and LEB. The new 3D geological and hydrostratigraphic model provides a framework to integrate additional hydrogeological and rock property data. It assists in refining hydraulic relationships between aquifers within the GAB and provides a basis for developing more detailed hydrogeological system conceptualisations. This is a step towards the future goal of quantifying hydraulic linkages with underlying basins, and overlying Cenozoic aquifers to underpin more robust understanding of the hydrogeological systems within the GAB. This approach can be extended to other regional hydrogeological systems. This Abstract was submitted/presented at the 2023 Australasian Exploration Geoscience Conference (AEGC) 13-18 March (https://2023.aegc.com.au/)

Publicly available groundwater data have been compiled to provide a common information base to inform environmental, resource development and regulatory decisions in the Galilee Basin region. This web service summarises salinity, water levels, resource size, potential aquifer yield and surface water–groundwater interactions for the Lake Eyre Basin located within the Galilee Basin region.

<div>The Lake Eyre surface water catchment covers around 1,200,000 km2 of central Australia, about one-sixth of the entire continent. It is one of the largest endorheic river basins in the world and contains iconic arid streams such as the Diamantina, Finke and Georgina rivers, and Cooper Creek. The Lake Eyre region supports diverse native fauna and flora, including nationally significant groundwater-dependent ecosystems such as springs and wetlands which are important cultural sites for Aboriginal Australians.</div><div><br></div><div>Much of the Lake Eyre catchment is underlain by the geological Lake Eyre Basin (LEB). The LEB includes major sedimentary depocentres such as the Tirari and Callabonna sub-basins which have been active sites of deposition throughout the Cenozoic. The stratigraphy of the LEB is dominated by the Eyre, Namba and Etadunna formations, as well as overlying Pliocene to Quaternary sediments.</div><div><br></div><div>The National Groundwater Systems Project, part of Geoscience Australia's Exploring for the Future Program (https://www.eftf.ga.gov.au/), is transforming our understanding of the nation's major aquifer systems. With an initial focus on the Lake Eyre Basin, we have applied an integrated geoscience systems approach to model the basin's regional stratigraphy and geological architecture. This analysis has significantly improved understanding of the extent and thickness of the main stratigraphic units, leading to new insights into the conceptualisation of aquifer systems in the LEB.</div><div><br></div><div>Developing the new understanding of the LEB involved compilation and standardisation of data acquired from thousands of petroleum, minerals and groundwater bores. This enabled consistent stratigraphic analysis of the major geological surfaces across all state and territory boundaries. In places, the new borehole dataset was integrated with biostratigraphic and petrophysical data, as well as airborne electromagnetic (AEM) data acquired through AusAEM (https://www.eftf.ga.gov.au/ausaem). The analysis and integration of diverse geoscience datasets helped to better constrain the key stratigraphic horizons and improved our overall confidence in the geological interpretations.</div><div><br></div><div>The new geological modelling of the LEB has highlighted the diverse sedimentary history of the basin and provided insights into the influence of geological structures on modern groundwater flow systems. Our work has refined the margins of the key depocentres of the Callabonna and Tirari sub-basins, and shown that their sediment sequences are up to 400 m thick. We have also revised maximum thickness estimates for the main units of the Eyre Formation (185 m), Namba Formation (265 m) and Etadunna Formation (180 m).</div><div><br></div><div>The geometry, distribution and thickness of sediments in the LEB is influenced by geological structures. Many structural features at or near surface are related to deeper structures that can be traced into the underlying Eromanga and Cooper basins. The occurrence of neotectonic features, coupled with insights from geomorphological studies, implies that structural deformation continues to influence the evolution of the basin. Structures also affect the hydrogeology of the LEB, particularly by compartmentalising groundwater flow systems in some areas. For example, the shallow groundwater system of the Cooper Creek floodplain is likely segregated from groundwater in the nearby Callabonna Sub-basin due to structural highs in the underlying Eromanga Basin.</div><div> Abstract submitted and presented at the 2023 Australian Earth Science Convention (AESC), Perth WA (https://2023.aegc.com.au/)

Publicly available groundwater data have been compiled to provide a common information base to inform environmental, resource development and regulatory decisions in the Adavale Basin region. This web service summarises salinity, water levels, resource size, potential aquifer yield and surface water–groundwater interactions for the Lake Eyre Basin located within the Adavale Basin region.

<div>Cooper Creek is a dryland river system that extends from the western Great Dividing Range in Central Queensland to Lake Eyre in South Australia. The middle course of the Cooper Creek is characterised by anabranching river channels across a wide floodplain that flow intermittently due to monsoonal flooding event higher in the catchment. As floodwaters recede, freshwater stagnates within numerous deeper segments of river channels forming ‘waterholes’ which support ecosystems with significant ecological and cultural value. However, there is little evidence that shallow groundwater discharges into these surface water bodies and the link between surface water and groundwater is not well understood. This study aims to demonstrate how airborne electromagnetics (AEM) and other geoscientific data can be integrated to identify recharge within shallow saline groundwater systems, which are so common in arid inland Australia.</div><div> The regional water table underneath the floodplain is shallow (<10m) and highly saline (>38,000 TDS), with a chemical signature suggesting salts were concentrated by evapotranspiration. Surface swelling clays likely limits the amount of recharge that occurs through the floodplain itself. However, a detailed study by Cendón et al (2010) found that during high flow events, floodwater scoured the base of the waterholes allowing freshwater to recharges into the shallow groundwater system forming chemically distinct freshwater lenses.</div><div> AEM is a geophysical technique capable of estimating bulk conductivity for the top few hundred metres of the subsurface. Part of the AusAEM Eastern Resource Corridor survey (Ley-Cooper 2021) crossed the Cooper Creek floodplain with a 20km line spacing. The bulk conductivity models delivered as part of this survey resolved the top of the saline water table regionally. In several locations, we identified resistive lenses sitting on the shallow water table which coincide with river channels that are frequently inundated.</div><div><br></div><div>Cendón, D.I., Larsen, J.R., Jones, B.G., Nanson, G.C., Rickleman, D., Hankin, S.I., Pueyo, J.J. and Maroulis, J., 2010. Freshwater recharge into a shallow saline groundwater system, Cooper Creek floodplain, Queensland, Australia.&nbsp;<em>Journal of Hydrology</em>,&nbsp;<em>392</em>(3-4), pp.150-163.</div><div>LeyCooper, Y. 2021. Exploring for the Future AusAEM Eastern Resources Corridor: 2021 Airborne Electromagnetic Survey TEMPEST® airborne electromagnetic data and GALEI inversion conductivity estimates. Geoscience Australia, Canberra.</div> This Abstract was submitted/presented to the 2022 Australasian Groundwater Conference 21-23 November (https://www.aig.org.au/events/australasian-groundwater-conference-2022/)

Publicly available groundwater data have been compiled to provide a common information base to inform environmental, resource development and regulatory decisions in the Galilee Basin region. This data guide gives examples of how these data can be used. The data package included with this data guide captures existing knowledge of Lake Eyre Basin aquifers in the Galilee Basin region and their properties, including salinity, water levels, resource size, potential aquifer yield and indicators of surface water interactions. The methods used to derive these data for the Lake Eyre Basin aquifer in the Galilee Basin region are outlined in the associated metadata files. These are described in groundwater conceptualisation models (Hostetler et al., 2023). The Lake Eyre Basin overlying the Galilee Basin includes one broadly defined aquifer that includes multiple aquifer systems that are defined as Cenozoic aquifers. Compiled data was assigned to this interval and were used to characterise groundwater systems at the basin scale. The data are compiled for a point-in-time to inform decisions on resource development activities Basin. The available historical groundwater data can be used to assess the potential effects on groundwater for different development scenarios. The data can also be used for other purposes, such as exploring unallocated groundwater resource potential. Data to January 2022 are used for this compilation.

<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)

Publicly available groundwater data have been compiled to provide a common information base to inform environmental, resource development and regulatory decisions in the Adavale Basin region. This web service summarises salinity, water levels, resource size, potential aquifer yield and surface water–groundwater interactions for the Lake Eyre Basin located within the Adavale Basin region.

Publicly available groundwater data have been compiled to provide a common information base to inform environmental, resource development and regulatory decisions in the Adavale Basin region. This data guide gives examples of how these data can be used. The data package included with this data guide captures existing knowledge of Lake Eyre Basin aquifers in the Adavale Basin region and their properties, including salinity, water levels, resource size, potential aquifer yield and surface water interactions. The methods to derive these data for the Lake Eyre Basin aquifer in the Adavale Basin region are outlined in the associated metadata files. These are described in groundwater conceptual models (Gouramanis et al., 2023). The Lake Eyre Basin overlying the Adavale Basin includes one broadly defined aquifer: Cenozoic hydrostratigraphic unit (Cenozoic aquifer). Compiled data are assigned to these intervals and used to characterise groundwater systems at the basin scale. The data are compiled for a point-in-time to inform decisions on potential resource developments in the Basin. The available historical groundwater data can be used to assess the potential effects on groundwater. The data can also be used for other purposes, such as exploring unallocated groundwater resource potential. Data to January 2022 are used for this compilation.

<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>