Multi-element geochemical surveys of rocks, soils, stream/lake/floodplain sediments, and regolith are typically carried out at continental, regional and local scales. The chemistry of these materials is defined by their primary mineral assemblages and their subsequent modification by comminution and weathering. Modern geochemical datasets represent a multi-dimensional geochemical space that can be studied using multivariate statistical methods from which patterns reflecting geochemical/geological processes are described (process discovery). These patterns form the basis from which probabilistic predictive maps are created (process validation). Processing geochemical survey data requires a systematic approach to effectively interpret the multi-dimensional data in a meaningful way. Problems that are typically associated with geochemical data include closure, missing values, censoring, merging, levelling different datasets, and adequate spatial sample design. Recent developments in advanced multivariate analytics, geospatial analysis and mapping provide an effective framework to analyze and interpret geochemical datasets. Geochemical and geological processes can often be recognized through the use of data discovery procedures such as the application of principal component analysis. Classification and predictive procedures can be used to confirm lithological variability, alteration, and mineralization. Geochemical survey data of lake/till sediments from Canada and of floodplain sediments from Australia show that predictive maps of bedrock and regolith processes can be generated. Upscaling a multivariate statistics-based prospectivity analysis for arc related Cu-Au mineralization from a regional survey in the southern Thomson Orogen in Australia to the continental scale, reveals a number of regions with similar (or stronger) multivariate response and hence potentially similar (or higher) mineral potential throughout Australia. <b>Citation:</b> E. C. Grunsky, P. de Caritat; State-of-the-art analysis of geochemical data for mineral exploration. <i>Geochemistry: Exploration, Environment, Analysis</i> 2019; 20 (2): 217–232. doi: https://doi.org/10.1144/geochem2019-031 This article appears in multiple journals (Lyell Collection & GeoScienceWorld)

<div>This Record documents the efforts of Geoscience Australia (GA) in compiling a New South Wales (NSW) Uranium–Lead (U–Pb) geochronology interpreted age compilation (version 1.0), utilising the MinView data from the Geological Survey of New South Wales (GSNSW), GA’s ‘in house’ storage of SHRIMP (Sensitive High Resolution Ion Micro Probe) ages, and other disparate publication sources e.g. academic journal articles and university theses. Here we describe both the dataset itself and the process by which it is incorporated into the continental-scale Isotopic Atlas of Australia. This initial release of the NSW geochronology compilation comprises of 1007 U–Pb ages of named and unnamed rock units in NSW.&nbsp;</div><div><br></div><div>The Isotopic Atlas draws together age and isotopic data from across the country and provides visualisations and tools to enable non-experts to extract maximum value from these datasets. Data is added to the Isotopic Atlas in a staged approach with priorities determined by GA- and partner-driven focus regions and research questions. This NSW U–Pb compilation represents the third in a series of compilation publications (Records and Datasets) for the southern states of Australia, which are a foundation for the second phase of the Exploring for the Future initiative over the period 2020–2024. All geochronology compilations in this series of Isotopic Atlas of Australia Records are available online from the Geochronology and Isotopes Data Portal. The most current data can be accessed and downloaded from GA’s Geochronology and Isotopes Data Portal.

The Pre-Cenozoic Geology of South Australia, New South Wales and Victoria removes Cenozoic geology. It is largely based on (1) the 1:1,000,000 Surface Geology by Geoscience Australia (2012) for New South Wales; (2) the Victoria seamless geology (2014); and (3) solid geology layers of South Australia by the Geological Survey of South Australia (2016), plus interpretation in GA of potential filed geophysical datasets, particularly magnetic data. The South Australia solid geology layers available on SARIG were used for Archaean to Ordovician geology of the state. Post-Ordovician geology of South Australia were interpreted in GA using magnetic data. The 1:1,000,000 surface geology map of the Mount Painter Region by S.B. Hore (2015) was also used. Solid geology was produced with the aid of interpretation of magnetic data for that region. For the Murray Basin and surrounding areas drill hole data were used to determine the geology under cover. Because extents of drill hole intercepted geology are not know in most cases. Such geology are shown as tiny circular polygons. The author thanks a number of state and GA geologists for their inputs at various stages of the project, particularly those who reviewed the data.

<div>This dataset represents the second version of a compilation of borehole stratigraphic unit data on a national scale (Figure 1). It builds on the previous Australian Borehole Stratigraphic Units Compilation (ABSUC) Version 1.0 (Vizy &amp; Rollet, 2023a) with additional new or updated stratigraphic interpretation on key boreholes located in Figure 2. Its purpose is to consolidate and standardise publicly accessible information from boreholes, including those related to petroleum, stratigraphy, minerals, and water. This compilation encompasses data from states and territories, as well as less readily available borehole logs and interpretations of stratigraphy.</div><div>&nbsp;</div><div>This study was conducted as part of the National Groundwater Systems (NGS) Project within the Australian Government's Exploring for the Future (EFTF) program. 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 net zero emissions, strong, sustainable 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. More information is available at http://www.ga.gov.au/eftf and https://www.eftf.ga.gov.au/national-groundwater-systems.</div><div>&nbsp;</div><div>As our understanding of Australian groundwater systems expands across states and territories, including legacy data from the 1970s and recent studies, it becomes evident that there is significant geological complexity and spatial variability in stratigraphic and hydrostratigraphic units nationwide. Recognising this complexity, there is a need to standardise diverse datasets, including borehole location and elevation, as well as variations in depth and nomenclature of stratigraphic picks. This standardisation aims to create a consistent, continent-wide stratigraphic framework for better understanding groundwater system for effective long-term water resource management and integrated resource assessments.</div><div>&nbsp;</div><div>This continental-scale compilation consolidates borehole data from 53 sources, refining 1,117,693 formation picks to 1,010,483 unique records from 171,396 boreholes across Australia. It provides a consistent framework for interpreting various datasets, enhancing 3D aquifer geometry and connectivity. Each data source's reliability is weighted, prioritising the most confident interpretations. Geological units conform to the Australian Stratigraphic Units Database (ASUD) for efficient updates. Regular updates are necessary to accommodate evolving information. Borehole surveys and dip measurements are excluded. As a result, stratigraphic picks are not adjusted for deviation, potentially impacting true vertical depth in deviated boreholes.</div><div>&nbsp;</div><div>This dataset provides:</div><div>ABSUC_v2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Australian stratigraphic unit compilation dataset (ABSUC)</div><div>ABSUC_v2_TOP&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A subset of preferred top picks from the ABSUC_v2 dataset</div><div>ABSUC_v2_BASE&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A subset of preferred base picks from the ABSUC_v2 dataset</div><div>ABSUC_BOREHOLE_v2&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;ABSUC Borehole collar dataset</div><div>ASUD_2023&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;A subset of the Australia Stratigraphic Units Database (ASUD)</div><div>&nbsp;</div><div>Utilising this uniform compilation of stratigraphic units, enhancements have been made to the geological and hydrogeological surfaces of the Great Artesian Basin, Lake Eyre Basin and Centralian Superbasin. This compilation is instrumental in mapping various regional groundwater systems and other resources throughout the continent. Furthermore, it offers a standardised approach to mapping regional geology, providing a consistent foundation for comprehensive resource impact assessments.</div>

The East Australian Current (EAC) onshore encroachment drives coastal upwelling and shelf circulations, changes slope-shelf bio-physical dynamics, and consequently exerts significant influence on coastal marine ecosystem along the south-eastern Australian margin. The EAC is a highly dynamic eddy-current system which exhibits high-frequency intrinsic fluctuations and eddy shedding. As a result, low-frequency variability in the EAC is usually overshadowed and rarely detectable. For decades, despite many efforts into the ocean current observations, the seasonality of EAC’s shoreward intrusion remains highly disputable. In this study, for the first time we use a long-term (26 years) remotely sensed AVHRR Sea Surface Temperature (SST) dataset spanning 1992-2018 to map the EAC off the coast of northern New South Wales (NSW), between 28°S - 32.5°S. A Topographic Position Index (TPI) image processing technique was applied to conduct the quantitative mapping. The mapping products have enabled direct measurement (area and distance) of the EAC’s shoreward intrusion. Subsequent spatial and temporal analyses have shown that the EAC move closer to the coast in austral summer and autumn than in austral winter, with the mean distance-to-coast ~6 km shorter and occupying the shelf area ~12% larger. This provides quantitative and direct evidence of the seasonality of the EAC’s shoreward intrusion. Such seasonal migration pattern of the EAC thus provides new insights into the seasonal upwelling and shelf circulations previously observed in this region. As a result, we were able to confirm that the EAC is a driving force of the seasonal ocean dynamics for the northern NSW coast.

The geology and mineral prospectivity of the southern Thomson Orogen is poorly understood because the vast majority of its extent is buried beneath younger regolith and/or sedimentary rocks. To address this issue a collaborative program to drill 16 stratigraphic boreholes was proposed to collect samples of the basement geology that can be comprehensively analysed to improve the understanding of the geological evolution of this region. To reduce the uncertainty associated with intersecting the target stratigraphy at each of the borehole sites, estimates of the cover thickness were obtained by applying the geophysical techniques of refraction seismic, audio-magnetotellurics (AMT) and targeted magnetic inversion modelling (TMIM) prior to drilling. Refraction seismic was acquired at all 16 proposed borehole sites using a system with 48 single-component geophones and a propelled weight drop primary-wave source. At 14 of the sites clear basement refractors were observed in the data. At the two other sites, Nantilla 1 and Barrygowan 1, loss of signal due to seismic attenuation at far offsets meant that a clear basement refractor was not observed. With the exception of these two sites, three distinct refractors are generally observed in the data. Those with velocities ranging from 0.4 km/s to 1.5 km/s are interpreted as regolith, those ranging from 1.8 km/s to 2.4 km/s are interpreted as Eromanga Basin sediments, and those ranging from 3.9 km/s to 5.7 km/s are interpreted as metamorphic/igneous basement. Two-dimensional velocity models of the subsurface geology were then generated using the time-term inversion method, which allowed for the thickness of each layer to be estimated. Cover thickness estimates using refraction data vary widely from site to site, with the shallowest estimate being Overshot 1 (49 m - 55 m) and the deepest Adventure Way 1 (295 m - 317 m). These variations in cover thickness estimates from site to site are indicative of basement topography variations and are not error margins. Audio-magnetotelluric data was collected at ten sites by simultaneously deploying four porous pot electrodes, to collect the two orthogonal components of telluric data (Ex and Ey), and three magnetic induction coils, to collect the three components of magnetic data (Hx, Hy and Hz). For each dataset, a one-dimensional inversion model was produced, from which resistivity contrasts were identified and used to describe electrical conductivity discontinuities in the subsurface geology. In general, the models show a near-surface conductive layer with resistivity values ≤10 Ω·m overlying layers with continuously increasing resistivities with depth (up to 102-103 Ω·m). Those layers which were >10 Ω·m were interpreted as metamorphic/igneous basement rocks and were observed to occur at depths of ~100 m to ~300 m across the survey sites, except at Overshot 1 (38 m ±10%) and Barrygowan 1 (480 m ±10%). Targeted magnetic inversion modelling (TMIM) was applied to freely available, good quality, regional airborne magnetic survey data. Depth to magnetic source estimates were generated for 53 targets, with confidence ratings, using a dipping tabular source body to model targeted magnetic anomalies in the vicinity of the borehole sites. A combined depth estimate was generated using a distance and confidence weighted average from multiple depth estimates at all but two borehole sites. Only a single depth estimate was available at Adventure Way 1 while no depth estimates were generated at Eulo 1. These combined depth estimates provide cover thickness estimates at the sites as they are likely sourced from, or near, the top of basement. Of the ten proposed borehole sites with coincident AMT and refraction seismic data, five sites have overlapping cover thickness estimates. Cover thickness estimates from the TMIM overlap both the AMT and refraction data at four sites and at two sites where only the refraction depth estimates were available. 2 Estimating Cover Thickness in the Southern Thomson Orogen The cover thickness estimates presented in this report lower the risks associated with the proposed southern Thomson Orogen stratigraphic drilling program by reducing the uncertainty in intersecting the target stratigraphy at each of the borehole sites as well as allowing for better project and program planning. Successful completion of the stratigraphic drilling program in the southern Thomson Orogen will allow for each of these geophysical methods for estimating cover thickness to be benchmarked using actual cover thicknesses measured in the boreholes.

<div>Defining and characterising groundwater aquifers usually depends on the availability of data necessary to represent its spatial extent and hydrogeological properties, such as lithological information and aquifer pump test data.&nbsp;In regions where such data is of limited availability and/or variable quality, the characterisation of aquifers for the purposes of water resource assessment and management can be problematic.&nbsp;The Upper Darling River Floodplain region of western New South Wales, Australia, is an area where communities, natural ecosystems and cultural values are dependent on both surface and groundwater resources.&nbsp;Owing to a relative paucity of detailed geological and hydrogeological data across the region we apply two non-invasive geophysical techniques—airborne electromagnetics and surface magnetic resonance—to assist in mapping and characterising the regional alluvial aquifer system.&nbsp;The combination of these techniques in conjunction with limited groundwater quality data helps define an approximate extent for the low salinity alluvial aquifer in a key part of the Darling River valley system and provides insights into the relative water content and its variation within the aquifer materials.&nbsp;This work demonstrates the utility of these key geophysical data in developing a preliminary understanding of aquifer geometry and heterogeneity, thereby helping to prioritise targets for follow-up hydrogeological investigation. Presented at the 2024 Australian Society of Exploration Geophysicists (ASEG) Discover Symposium

This data package, completed as part of Geoscience Australia’s National Groundwater Systems (NGS) Project, presents results of the second iteration of the 3D Great Artesian Basin (GAB) and Lake Eyre Basin (LEB) (Figure 1) geological and hydrogeological models (Vizy & Rollet, 2023) populated with volume of shale (Vshale) values calculated on 2,310 wells in the Surat, Eromanga, Carpentaria and Lake Eyre basins (Norton & Rollet, 2023). This provides a refined architecture of aquifer and aquitard geometry that can be used as a proxy for internal, lateral, and vertical, variability of rock properties within each of the 18 GAB-LEB hydrogeological units (Figure 2). These data compilations and information are brought to a common national standard to help improve hydrogeological conceptualisation of groundwater systems across multiple jurisdictions. This information will assist water managers to support responsible groundwater management and secure groundwater into the future. This 3D Vshale model of the GAB provides a common framework for further data integration with other disciplines, industry, academics and the public and helps assess the impact of water use and climate change. It aids in mapping current groundwater knowledge at a GAB-wide scale and identifying critical groundwater areas for long-term monitoring. The NGS project is part of the Exploring for the Future (EFTF) program—an eight-year, $225 million Australian Government funded geoscience data and precompetitive information acquisition program. The program seeks to inform decision-making by government, community, and industry on the sustainable development of Australia's mineral, energy, and groundwater resources, including those to support the effective long-term management of GAB water resources. This work builds on the first iteration completed as part of the Great Artesian Basin Groundwater project (Vizy & Rollet, 2022; Rollet et al., 2022), and infills previous data and knowledge gaps in the GAB and LEB with additional borehole, airborne electromagnetic and seismic interpretation. The Vshale values calculated on additional wells in the southern Surat and southern Eromanga basins and in the whole of Carpentaria and Lake Eyre basins provide higher resolution facies variability estimates from the distribution of generalised sand-shale ratio across the 18 GAB-LEB hydrogeological units. The data reveals a complex mixture of sedimentary environments in the GAB, and highlights sand body development and hydraulic characteristics within aquifers and aquitards. Understanding the regional extents of these sand-rich areas provides insights into potential preferential flow paths, within and between the GAB and LEB, and aquifer compartmentalisation. However, there are limitations that require further study, including data gaps and the need to integrate petrophysics and hydrogeological data. Incorporating major faults and other structures would also enhance our understanding of fluid flow pathways. The revised Vshale model, incorporating additional boreholes to a total of 2,310 boreholes, contributes to our understanding of groundwater flow and connectivity in the region, from the recharge beds to discharge at springs, and Groundwater Dependant Ecosystems (GDEs). It also facilitates interbasinal connectivity analysis. This 3D Vshale model offers a consistent framework for integrating data from various sources, allowing for the assessment of water use impacts and climate change at different scales. It can be used to map groundwater knowledge across the GAB and identify areas that require long-term monitoring. Additionally, the distribution of boreholes with gamma ray logs used for the Vshale work in each GAB and LEB units (Norton & Rollet, 2022; 2023) is used to highlight areas where additional data acquisition or interpretation is needed in data-poor areas within the GAB and LEB units. The second iteration of surfaces with additional Vshale calculation data points provides more confidence in the distribution of sand bodies at the whole GAB scale. The current model highlights that the main Precipice, Hutton, Adori-Springbok and Cadna-owie‒Hooray aquifers are relatively well connected within their respective extents, particularly the Precipice and Hutton Sandstone aquifers and equivalents. The Bungil Formation, the Mooga Sandstone and the Gubberamunda Sandstone are partial and regional aquifers, which are restricted to the Surat Basin. These are time equivalents to the Cadna-owie–Hooray major aquifer system that extends across the Eromanga Basin, as well as the Gilbert River Formation and Eulo Queen Group which are important aquifers onshore in the Carpentaria Basin. The current iteration of the Vshale model confirms that the Cadna-owie–Hooray and time equivalent units form a major aquifer system that spreads across the whole GAB. It consists of sand bodies within multiple channel belts that have varying degrees of connectivity' i.e. being a channelised system some of the sands will be encased within overbank deposits and isolated, while others will be stacked, cross-cutting systems that provide vertical connectivity. The channelised systemtransitions vertically and laterally into a shallow marine environment (Rollet et al., 2022). Sand-rich areas are also mapped within the main Poolowanna, Brikhead-Walloon and Westbourne interbasinal aquitards, as well as the regional Rolling Downs aquitard that may provide some potential pathways for upward leakage of groundwater to the shallow Winton-Mackunda aquifer and overlying Lake Eyre Basin. Further integration with hydrochemical data may help groundtruth some of these observations. This metadata document is associated with a data package including: • Seventeen surfaces with Vshale property (Table 1), • Seventeen surfaces with less than 40% Vshale property (Table 2), • Twenty isochore with average Vshale property (Table 3), • Twenty isochore with less than 40% Vshale property (Table 4), • Sixteen Average Vshale intersections of less than 40% Vshale property delineating potential connectivity between isochore (Table 5), • Sixteen Average Vshale intersections of less than 40% Vshale property delineating potential connectivity with isochore above and below (Table 6), • Seventeen upscaled Vshale log intersection locations (Table 7), • Six regional sections showing geology and Vshale property (Table 8), • Three datasets with location of boreholes, sections, and area of interest (Table 9).

<div>Groundwater dependent ecosystems (GDEs) rely on access to groundwater on a permanent or intermittent basis to meet some or all of their water requirements (Richardson et al., 2011). The <a href="https://explorer-aws.dea.ga.gov.au/products/ga_ls_tc_pc_cyear_3">Tasselled Cap percentile products</a> created by Digital Earth Australia (2023) were used to identify potential GDEs for the upper Darling River floodplain study area. These percentile products provide statistical summaries (10th, 50th, 90th percentiles) of landscape brightness, greenness and wetness in imagery acquired between 1987 and present day. The 10th percentile greenness and wetness represent the lowest 10% of values for the time period evaluated, e.g. 10th greenness represents the least green period. In arid regions, areas that are depicted as persistently green and/or wet at the 10th percentile have the greatest potential to be GDEs. For this reason, and due to accessibility of the data, the 10th percentile Tasselled Cap greenness (TCG) and Tasselled Cap wetness (TCW) products were used as the basis for the assessment of GDEs for the upper Darling River floodplain study area. </div><div><br></div><div>This data release is an ESRI geodatabase, with layer files, including:</div><div><br></div><div>-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;original greenness and wetness datasets extracted; </div><div><br></div><div>-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;classified 10th percentile greenness and wetness datasets (used as input for the combined dataset); </div><div><br></div><div>-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;combined scaled 10th percentile greenness and wetness dataset (useful for a quick glance to identify potential groundwater dependent vegetation (GDV) that have high greenness and wetness e.g. river red gums)</div><div><br></div><div>-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;combined classified 10th percentile greenness and wetness dataset (useful to identify potential GDV/GDE and differentiate between vegetation types)</div><div><br></div><div>-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;coefficient of variation of 50th percentile greenness dataset (useful when used in conjunction with the scaled/combined products to help identify GDEs)</div><div><br></div><div>For more information and detail on these products, refer to <a href="https://dx.doi.org/10.26186/148545">https://dx.doi.org/10.26186/148545</a>.</div><div><br></div><div><strong>References</strong></div><div>Digital Earth Australia (2023). <em><a href="https://docs.dea.ga.gov.au">Digital Earth Australia User Guide</a></em>. </div><div>Richardson, S., E. Irvine, R. Froend, P. Boon, S. Barber, and B. Bonneville. 2011a. <em>Australian groundwater-dependent ecosystem toolbox part 1: Assessment framework.</em> Waterlines Report 69. Canberra, Australia: Waterlines.</div>

This report, completed as part of Geoscience Australia’s Exploring for the Future Program National Groundwater Systems (NGS) Project, presents results of the second iteration of 3D geological and hydrogeological surfaces across eastern Australian basins. The NGS project is part of the Exploring for the Future (EFTF) program—an eight-year, $225 million Australian Government funded geoscience data and precompetitive information acquisition program. The program seeks to inform decision-making by government, community, and industry on the sustainable development of Australia's mineral, energy, and groundwater resources, including those to support the effective long-term management of GAB water resources. This work builds on the first iteration completed as part of the Great Artesian Basin Groundwater project. The datasets incorporate infills of data and knowledge gaps in the Great Artesian Basin (GAB), Lake Eyre Basin (LEB), Upper Darling Floodplain (UDF) and existing data in additional basins in eastern Australia. The study area extends from the offshore Gulf of Carpentaria in the north to the offshore Bight, Otway, and Gippsland basins in the South and from the western edge of the GAB in the west to the eastern Australian coastline to the east. The revisions are an update to the surface extents and thicknesses for 18 region-wide hydrogeological units produced by Vizy & Rollet, 2022. The second iteration of the 3D model surfaces further unifies geology across borders and provides the basis for a consistent hydrogeological framework at a basin-wide, and towards a national-wide, scale. The stratigraphic nomenclature used follows geological unit subdivisions applied: (1) in the Surat Cumulative Management Area (OGIA - Office of Groundwater Impact Assessment, 2019) to correlate time equivalent regional hydrogeological units in the GAB and other Jurassic and Cretaceous time equivalent basins in the study area and (2) in the LEB to correlate Cenozoic time equivalents in the study area. Triassic to Permian and older basins distribution and thicknesses are provided without any geological and hydrogeological unit sub-division. Such work helps to (1) reconcile legacy and contemporary regional studies under a common stratigraphic framework, (2) support the effective management of groundwater resources, and (3) provide a regional geological context for integrated resource assessments. The 18 hydrogeological units were constructed using legacy borehole data, 2D seismic and airborne electromagnetic (AEM) data that were compiled for the first iteration of the geological and hydrogeological surfaces under the GAB groundwater project (Vizy & Rollet, 2022a) with the addition of: • New data collected and QC’d from boreholes (including petroleum, CSG [Coal Seam Gas], stratigraphic, mineral and water boreholes) across Australia (Vizy & Rollet, 2023a) since the first iteration, including revised stratigraphic correlations filling data and knowledge gaps in the GAB, LEB, UDF region (Norton & Rollet, 2023) with revised palynological constraints (Hannaford & Rollet 2023), • Additional AEM interpretation since the first iteration in the GAB, particularly in the northern Surat (McPherson et al., 2022b), as well as in the LEB (Evans et al., in prep), in the southern Eromanga Basin (Wong et al., 2023) and in the UDF region (McPherson et al., 2022c), and • Additional 2D seismic interpretation in the Gulf of Carpentaria (Vizy & Rollet, 2023b) and in the western and central Eromanga Basin (Szczepaniak et al., 2023). These datasets were then analysed and interpreted in a common 3D domain using a consistent chronostratigraphic framework tied to the geological timescale of 2020, as defined by Hannaford et al. (2022). Confidence maps were also produced to highlight areas that need further investigation due to data gaps, in areas where better seismic depth conversion or improved well formation picks are required. New interpretations from the second iteration of the 18 surfaces include (1) new consistent and regionally continuous surfaces of Cenozoic down to Permian and older sediments beyond the extent of the GAB across eastern Australia, (2) revised extents and thicknesses of Jurassic and Cretaceous units in the GAB, including those based on distributed thickness, (3) revised extents and thicknesses of Cenozoic LEB units constrained by the underlying GAB 3D model surfaces geometry. These data constraints were not used in the model surfaces generated for the LEB detailed inventory (Evans et al., 2023), and (4) refinements of surfaces due to additional seismic and AEM interpretation used to infill data and knowledge gaps. Significant revisions include: • The use of additional seismic data to better constrain the base of the Poolowanna-Evergreen formations and equivalents and the top of Cadna-owie Formation and equivalents in the western and central Eromanga Basin, and the extent and thicknesses of the GAB units and Cenozoic Karumba Basin in the Gulf of Carpentaria, • The use of AEM interpretations to refine the geometry of outcropping units in the northern Surat Basin and the basement surface underneath the UDF region, and • A continuous 3D geological surface of base Cenozoic sediments across eastern Australia including additional constraints for the Lake Eyre Basin (borehole stratigraphy review), Murray Basin (AEM interpretation) and Karumba Basin (seismic interpretation). These revisions to the 18 geological and hydrogeological surfaces will help improve our understanding on the 3D spatial distribution of aquifers and aquitards across eastern Australia, from the groundwater recharge areas to the deep confined aquifers. These data compilations and information brought to a common national standard help improve hydrogeological conceptualisation of groundwater systems across multiple jurisdictions to assist water managers to support responsible groundwater management and secure groundwater into the future. These 3D geological and hydrogeological modelled surfaces also provide a tool for consistent data integration from multiple datasets. These modelled surfaces bring together variable data quality and coverage from different databases across state and territory jurisdictions. Data integration at various scale is important to assess potential impact of different water users and climate change. The 3D modelled surfaces can be used as a consistent framework to map current groundwater knowledge at a national scale and help highlight critical groundwater areas for long-term monitoring of potential impacts on local communities and Groundwater Dependant Ecosystems. The distribution and confidence on data points used in the current iteration of the modelled surfaces highlight where data poor areas may need further data acquisition or additional interpretation to increase confidence in the aquifers and aquitards geometry. The second iteration of surfaces highlights where further improvements can be made, notably for areas in the offshore Gulf of Carpentaria with further seismic interpretation to better constrain the base of the Aptian marine incursion (to better constrain the shape and offshore extent of the main aquifers). Inclusion of more recent studies in the offshore southern and eastern margins of Australia will improve the resolution and confidence of the surfaces, up to the edge of the Australian continental shelf. Revision of the borehole stratigraphy will need to continue where more recent data and understanding exist to improve confidence in the aquifer and aquitard geometry and provide better constraints for AEM and seismic interpretation, such as in the onshore Carpentaria, Clarence-Moreton, Sydney, Murray-Darling basins. Similarly adding new seismic and AEM interpretation recently acquired and reprocessed, such as in the eastern Eromanga Basin over the Galilee Basin, would improve confidence in the surfaces in this area. Also, additional age constraints in formations that span large periods of time would help provide greater confidence to formation sub-divisions that are time equivalent to known geological units that correlate to major aquifers and aquitards in adjacent basins, such as within the Late Jurassic‒Early Cretaceous in the Eromanga and Carpentaria basins. Finally, incorporating major faults and structures would provide greater definition of the geological and hydrogeological surfaces to inform with greater confidence fluid flow pathways in the study area. This report is associated with a data package including (Appendix A – Supplementary material): • Nineteen geological and hydrogeological surfaces from the Base Permo-Carboniferous, Top Permian, Base Jurassic, Base Cenozoic to the surface (Table 1.1), • Twenty-one geological and hydrogeological unit thickness maps from the top crystalline basement to the surface (Figure 3.1 to Figure 3.21), • The formation picks and constraining data points (i.e., from boreholes, seismic, AEM and outcrops) compiled and used for gridding each surface (Table 2.7). Detailed explanation of methodology and processing is described in the associated report (Vizy & Rollet, 2023).