<div>This data package contains the main hydrogeological datasets compiled, analysed, developed, and used for the Geoscience Australia project that investigated the Cenozoic geology, hydrogeology, and groundwater systems of the Kati Thanda - Lake Eyre Basin in central Australia. This work, which was published as Geoscience Australia Record 2024/05 (Evans et al. 2024), was delivered as part of the National Groundwater Systems project in the Exploring for the Future program.</div><div><br></div><div>The hydrogeological and groundwater data includes new aquifer and aquifer province attribution for many thousands of groundwater bores, large-scale compilations of existing water level, salinity, and hydrogeochemical data, and new mapping of regional watertable trends and depth to standing water across the basin. These data are represented within the Geoscience Australia Record as various maps and related diagrams.</div><div><br></div><div>Reference: Evans TJ, Bishop C, Symington NJ, Halas L, Hansen JWH, Norton CJ, Hannaford C and Lewis SJ (2024) Cenozoic geology, hydrogeology, and groundwater systems: Kati Thanda – Lake Eyre Basin, Record 2024/05, Geoscience Australia, Canberra, http://dx.doi.org/10.26186/147422.</div><div><br></div>

<div>The Kati Thanda – Lake Eyre Basin (KT–LEB) covers about 1.2 million square kilometres of outback Australia. Although the basin is sparsely populated and relatively undeveloped it hosts nationally significant environmental and cultural heritage, including unique desert rivers, sweeping arid landscapes, and clusters of major artesian springs. The basin experiences climatic extremes that intermittently cycle between prolonged droughts and massive inland floods, with groundwater resources playing a critical role in supporting the many communities, industries, ecological systems, and thriving First Nations culture of the KT–LEB.</div><div><br></div><div>As part of Geoscience Australia’s National Groundwater Systems Project (in the Exploring for the Future Program) this report brings together contemporary data and information relevant to understanding the regional geology, hydrogeology and groundwater systems of Cenozoic rocks and sediments of the KT–LEB. This work represents the first whole-of-basin assessment into these vitally important shallow groundwater resources, which have previously received far less scientific attention than the deeper groundwater systems of the underlying Eromanga Basin (part of the Great Artesian Basin). The new knowledge and insights about the geology and hydrogeology of the basin generated by this study will benefit the many users of groundwater within the region and will help to improve sustainable management and use of groundwater resources across the KT–LEB.</div><div><br></div>

<div>Around the world the Earth's crust is blanketed to various extents by sedimentary cover. For continental regions, knowledge of the distribution and thickness of sediments is crucial for a wide range of applications including seismic hazard, resource potential, and our ability to constrain the deeper crustal geology. Excellent constraints on the sedimentary thickness can be obtained from borehole drilling or active seismic surveys. However, these approaches are expensive and impractical in remote continental interiors such as central Australia. </div><div><br></div><div>Recently, a method for estimating the sedimentary thickness using passive seismic data, the collection of which is relatively simple and low-cost, was developed and applied to seismic stations in South Australia. This method uses receiver functions, specifically the time delay of the \P{}-to-\S{} converted phase generated at the sediment-basement interface, relative to the direct-P arrival, to generate a first order estimate of the thickness of sedimentary cover. In this work we expand the analysis to the vast array of over 1500 seismic stations across Australia, covering an entire continent and numerous sedimentary basins that span the entire range from Precambrian to present-day. We compare with an established yet separate method to estimate the sedimentary thickness, which utilises the autocorrelation of the radial receiver functions to ascertain the two-way travel-time of shear waves reverberating in a sedimentary layer.</div><div><br></div><div>Across the Australian continent the new results clearly match the broad pattern of expected sedimentation based on the various geological provinces. Furthermore we are able to delineate the boundaries of many sedimentary features, such as the Eucla and Murray Basins, which are Cenozoic, and the boundary between the Karumba Basin and the mineral rich Mount Isa Province. The signal is found to diminish for older Proterozoic basins, likely due to compaction and metamorphism of the sediments over time. Finally, a comparison with measurements of sedimentary thickness from local boreholes allows for a straightforward predictive relationship between the delay time and the cover thickness to be defined. This offers future widespread potential, providing a simple and cheap way to characterise the sedimentary thickness in under-explored areas from passive seismic data. </div><div><br></div><div>This study and some of the data used are funded and supported by the Australian Government's Exploring for the Future program led by Geoscience Australia.</div> <b>Citation:</b> Augustin Marignier, Caroline M Eakin, Babak Hejrani, Shubham Agrawal, Rakib Hassan, Sediment thickness across Australia from passive seismic methods, <i>Geophysical Journal International</i>, Volume 237, Issue 2, May 2024, Pages 849–861, <a href="https://doi.org/10.1093/gji/ggae070">https://doi.org/10.1093/gji/ggae070</a>

<div>The geological data includes the spatial extents of the Kati Thanda - Lake Eyre Basin (KT-LEB) project area, geological basin and sub-basin boundaries, and geological models of the extent and thickness of the main Cenozoic sedimentary packages in the KT-LEB in central Australia. This data package has particular focus on the geological Lake Eyre Basin (LEB) and its main sedimentary depocentres of the Callabonna and Tirari sub-basins, and the Cooper Creek Palaeovalley. The new geological datasets available in this data package were developed as part of the project on the Cenozoic geology, hydrogeology, and groundwater systems of the Kati Thanda - Lake Eyre Basin, the results of which were published in Evans et al. (2024). This activity was undertaken as part of the National Groundwater Systems project in the Geoscience Australia Exploring for the Future program.</div><div><br></div><div>This geological data package contains the following eight datasets:</div><div>1. Spatial extents of the boundary of the KT–LEB project area.</div><div>2. Major sites of Cenozoic sediment deposition within the KT-LEB.</div><div>3. Total thickness of Cenozoic sediments in KT-LEB, with derived contours, hillshaded image and Cenozoic cover extent. </div><div>4. Saturated thickness model of Cenozoic sediments in the KT-LEB with derived contours, hillshaded image and Cenozoic cover extent.</div><div>5. Model of the base of Cenozoic surface of the KT-LEB project area, with derived contours, hill-shaded image and Cenozoic cover extent.</div><div>6. Model of thickness of Quaternary sediments of the KT-LEB with derived contours, hillshaded image and the Quaternary sediments extent outline.</div><div>7. Model of thickness of Namba Formation in KT-LEB, with derived contours, hillshaded image and the Namba Formation extent outline.</div><div>8. Model of thickness of Eyre Formation in KT-LEB with derived contours, hillshaded image and the Eyre Formation extent outline.</div><div><br></div><div>Reference:</div><div>Evans TJ, Bishop C, Symington NJ, Halas L, Hansen JWH, Norton CJ, Hannaford C and Lewis SJ (2024) <em>Cenozoic geology, hydrogeology, and groundwater systems: Kati Thanda – Lake Eyre Basin</em>, Record 2024/05, Geoscience Australia, Canberra, http://dx.doi.org/10.26186/147422.</div><div><br></div>