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)

This record presents new zircon U-Pb geochronological data, obtained via Sensitive High Resolution Ion Microprobe (SHRIMP) for eleven samples of plutonic and volcanic rocks from the Lachlan Orogen, and the New England Orogen. The work is part of an ongoing Geochronology Project (Metals in Time), conducted by the Geological Survey of New South Wales (GSNSW) and Geoscience Australia (GA) under a National Collaborative Framework (NCF) agreement, to better understand the geological evolution of New South Wales. The results herein (summarised in Table 1.1 and Table 1.2) correspond to zircon U-Pb SHRIMP analysis undertaken on GSNSW mineral systems projects for the reporting period July 2015-June 2016. Lachlan Orogen In the Lachlan Orogen, the age of 418.9 ± 2.5 Ma for the Babinda Volcanics is consistent with the accepted stratigraphy of its parent Kopyje Group, agrees with the ages of other I-type volcanic rocks within the Canbelego-Mineral Hill Volcanic Belt and indicates eruption and emplacement of this belt during a single event. The age of the Shuttleton Rhyolite Member (421.9 ± 2.7 Ma) of the Amphitheatre Group is compatible with recent U-Pb dating of the Mount Halfway Volcanics, which interfingers with the Amphitheatre Group (MacRae, 1987). The age is also similar to nearby S-type granite intrusions, which suggests that the limited eruptive volcanic activity in the region was accompanied by local coeval plutonism. The results for the Babinda Volcanics and Shuttleton Rhyolite Member, in conjunction with previous GA dating and other dating and studies (summarised in Downes et al., 2016) establishes that significant igneous activity occurred between ~423 and ~418 Ma within the Cobar region but comprised two compositionally distinct but broadly contemporaneous belts of volcanics and comagmatic granite intrusions. The new age for the unnamed quartz monzonite at Hobbs Pipe constrains the maximum age of the hosted gold mineralisation to 414.7 ± 2.6 Ma. The wide range in ages for granites along the Gilmore Suture suggests that mineralisation in this region is not necessarily constrained to a single short-lived event. The new age of 413.5 ± 2.3 Ma for volcanics at Yerranderie indicates that that the Bindook Volcanic Complex was erupted over a relatively short period, and also indicates that the epithermal mineralisation at Yerranderie was not genetically related to the host volcanics but probably to a younger rifting event in the east Lachlan. New England Orogen Four units were dated from the Clarence River Supersuite in the New England Orogen. All four are between 255 and 256 Ma, demonstrating that these granites are related chemically, spatially, and temporally. While these four ages are indistinguishable, the current age span for Clarence River Supersuite is more than 40 million years. This wide age range indicates that classification of granites into the Clarence River Supersuite needs further refinement. The new age for the Newton Boyd Granodiorite (252.8 ± 1.0 Ma) is similar to some previously dated units within the Herries Supersuite, but both the Herries Supersuite and Stanthorpe Supersuite (into which the Herries Supersuite was reclassified by Donchak, 2013) incorporate units with a broad range of ages: the age distribution for the Stanthorpe Supersuite spans 50 million years. Classification of granites in the New England Orogen in New South Wales is worth revisiting. Two units were dated from the Drake Volcanics, nominally in the Wandsworth Volcanic Group and indicate that the middle to upper section of the Drake Volcanics, including the mineralising intrusions, were emplaced within the space of 1-2 million years. These results support a genetic and temporal link between the Au-Ag epithermal mineralisation at White Rock and Red Rock and their host Drake Volcanic packages rather than to younger regional plutonism (i.e., Stanthorpe Supersuite) or volcanism (i.e., Wandsworth Volcanics). The almost 10 Ma gap between the Drake Volcanics and the next lowest units of the Wandsworth Volcanic Group supports the argument for considering the Drake Volcanics a distinct unit.

<div>As part of the Delamerian Margins NSW National Drilling Initiative campaign, seventeen stratigraphic boreholes were drilled between Broken Hill and Wentworth, in Western NSW. These holes were designed to test stratigraphic, structural, and mineral systems questions in the New South Wales portion of the Delamerian Margin. Drilling was conducted between March and June 2023 and was undertaken by Geoscience Australia in collaboration with MinEx CRC. This report outlines basic borehole targeting rationale, borehole metadata, and analyses performed immediately following drilling to accompany data available through the Geoscience Australia portal.</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 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.</div>

<div>This data package contains interpretations of airborne electromagnetic (AEM) conductivity sections in the Exploring for the Future (EFTF) program’s Eastern Resources Corridor (ERC) study area, in south eastern Australia. Conductivity sections from 3 AEM surveys were interpreted to provide a continuous interpretation across the study area – the EFTF AusAEM ERC (Ley-Cooper, 2021), the Frome Embayment TEMPEST (Costelloe et al., 2012) and the MinEx CRC Mundi (Brodie, 2021) AEM surveys. Selected lines from the Frome Embayment TEMPEST and MinEx CRC Mundi surveys were chosen for interpretation to align with the 20&nbsp;km line-spaced EFTF AusAEM ERC survey (Figure 1).</div><div>The aim of this study was to interpret the AEM conductivity sections to develop a regional understanding of the near-surface stratigraphy and structural architecture. To ensure that the interpretations took into account the local geological features, the AEM conductivity sections were integrated and interpreted with other geological and geophysical datasets, such as boreholes, potential fields, surface and basement geology maps, and seismic interpretations. This approach provides a near-surface fundamental regional geological framework to support more detailed investigations. </div><div>This study interpreted between the ground surface and 500&nbsp;m depth along almost 30,000 line kilometres of nominally 20&nbsp;km line-spaced AEM conductivity sections, across an area of approximately 550,000&nbsp;km2. These interpretations delineate the geo-electrical features that correspond to major chronostratigraphic boundaries, and capture detailed stratigraphic information associated with these boundaries. These interpretations produced approximately 170,000 depth estimate points or approximately 9,100 3D line segments, each attributed with high-quality geometric, stratigraphic, and ancillary data. The depth estimate points are formatted for compliance with Geoscience Australia’s (GA) Estimates of Geological and Geophysical Surfaces (EGGS) database, the national repository for standardised depth estimate points. </div><div>Results from these interpretations provided support to stratigraphic drillhole targeting, as part of the Delamerian Margins NSW National Drilling Initiative campaign, a collaboration between GA’s EFTF program, the MinEx CRC National Drilling Initiative and the Geological Survey of New South Wales. The interpretations have applications in a wide range of disciplines, such as mineral, energy and groundwater resource exploration, environmental management, subsurface mapping, tectonic evolution studies, and cover thickness, prospectivity, and economic modelling. It is anticipated that these interpretations will benefit government, industry and academia with interest in the geology of the ERC region.</div>

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>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.</div><div><br></div>

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.

Geoscience Australia’s Exploring for the Future (EFTF) 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. Further detail is available at http://www.ga.gov.au/eftf. The National Groundwater Systems (NGS) project, is part of the Australian Government’s Exploring for the Future (EFTF) program, led by Geoscience Australia (https://www.eftf.ga.gov.au/national-groundwater-systems), to improve understanding of Australia’s groundwater resources to better support responsible groundwater management and secure groundwater resources into the future. The project is developing new national data coverages to constrain groundwater systems, develop a new map of Australian groundwater systems and improve data standards and workflows of groundwater assessment to populate a consistent data discovery tool and web-based mapping portal to visualise, analyse and download hydrogeological information. While our hydrogeological conceptual understanding of Australian groundwater systems continues to grow in each State and Territory jurisdiction, in addition to legacy data and knowledge from the 1970s, new information provided by recent studies in various parts of Australia highlights the level of geological complexity and spatial variability in stratigraphic and hydrostratigraphic units across the continent. We recognise the need to standardise individual datasets, such as the location and elevation of boreholes recorded in different datasets from various sources, as well as the depth and nomenclature variations of stratigraphic picks interpreted across jurisdictions to map such geological complexity in a consistent, continent-wide stratigraphic framework that can support effective long-term management of water resources and integrated resource assessments. This stratigraphic units data compilation at a continental scale forms a single point of truth for basic borehole data including 47 data sources with 1 802 798 formation picks filtered to 1 001 851 unique preferred records from 171 367 boreholes. This data compilation provides a framework to interpret various borehole datasets consistently, and can then be used in a 3D domain as an input to improve the 3D aquifer geometry and the lateral variation and connectivity in hydrostratigraphic units across Australia. The reliability of each data source is weighted to use preferentially the most confident interpretation. Stratigraphic units are standardised to the Australian Stratigraphic Units Database (ASUD) nomenclature (https://asud.ga.gov.au/search-stratigraphic-units) and assigned the corresponding ASUD code to update the information more efficiently when needed. This dataset will need to be updated as information grows and is being revised over time. This dataset provides: 1. ABSUC_v1 Australian stratigraphic unit compilation dataset (ABSUC) 2. ABSUC_v1_TOP A subset of preferred top picks from the ABSUC_v1 dataset 3. ABSUC_v1_BASE A subset of preferred base picks from the ABSUC_v1 dataset 4. ABSUC_BOREHOLE_v1 ABSUC Borehole collar dataset 5. ASUD_2023 A subset of the Australia Stratigraphic Units Database (ASUD) This consistent stratigraphic units compilation has been used to refine the Great Artesian Basin geological and hydrogeological surfaces in this region and will support the mapping of other regional groundwater systems and other resources across the continent. It can also be used to map regional geology consistently for integrated resource assessments.

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.

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.