<div>At the 2021 AESC (Australian Earth Sciences Convention), Geoscience Australia (GA) introduced a continental-scale Isotopic Atlas of Australia (Fraser et al., 2020) through an interactive poster display (Fraser et al., 2021). In the two years since, progress on this Isotopic Atlas has continued and expanded datasets are now publicly available and downloadable via Geoscience Australia’s Exploring for the Future (EFTF) Geochronology and Isotopes Data Portal.</div><div><br></div><div>This poster provides example maps produced from the compiled data of multiple geochronology and isotopic tracer datasets, now available in the Geochronology and Isotopes Data Portal. Available data include Sm–Nd model ages of magmatic rocks (Champion et al., 2013); Lu–Hf isotopes from zircon and associated O-isotope data (Waltenberg et al., 2023); Pb–Pb isotopes from ore-related minerals such as galena and pyrite (Huston et al., 2019); Rb–Sr stable isotopes from surface regolith (de Caritat et al., 2022, 2023); U–Pb interpreted ages of magmatic, metamorphic and sedimentary rocks (Jones et al., 2018); and K–Ar, Ar–Ar, Re–Os, Rb–Sr and fission-track interpreted ages from minerals and whole rocks.</div><div><br></div><div>Significant recent additions to the datasets include geochronology compilations for Victoria (Waltenberg et al., 2021) and Tasmania (Jones et al., 2022) and full geochronology analytical data tables for GA’s SHRIMP (Sensitive High Resolution Ion Micro Probe) U–Pb results. The online data portal provides tools for visualizing data in commonly-used diagrammatic formats (e.g. Time-Space style plots for geochronology, isotope evolution diagrams for Nd and Hf data). Data are also available for download in a range of formats (CSV, JSON, KML, Shapefile) to allow manipulation and visualization offline for specific purposes.</div><div><br></div><div>Work is ongoing to improve the coverage of legacy interpreted ages geochronology data, to include geochronology analytical data tables for both ID-TIMS and LA-ICP-MS data, and to update the Sm-Nd and Pb-Pb in ores coverages with new data. New work is in progress to develop a Pb-Pb isotopic coverage from representative ‘basement’ rocks (Liebmann et al., 2022) and to expand the coverage of oxygen and Lu-Hf isotopes from zircon, with a current focus in south-eastern Australia (Mole et al., 2022).</div><div><br></div><div>This Isotopic Atlas of Australia provides a convenient visual overview of age and isotopic patterns reflecting geological processes that have led to the current configuration of the Australian continent, including progressive development of continental crust from the mantle. These datasets and maps unlock the collective value of several decades of geochronological and isotopic studies conducted across Australia, and provide an important complement to other geological maps and geophysical images—in particular, by adding a time dimension to 2D and 3D maps and models.</div> Abstract/Poster submitted and presented at 2023 Australian Earth Science Convention (AESC), Perth WA (https://2023.aegc.com.au/)

<div>The ‘Major crustal boundaries of Australia’ data set synthesises more than 40 years of acquisition of deep seismic reflection data across Australia, where major crustal-scale breaks, often inferred to be relict sutures between different crustal blocks, have been interpreted in the seismic reflection profiles. The widespread coverage of the seismic profiles now provides the opportunity to construct a map of major crustal boundaries across Australia. Starting with the locations of the crustal breaks identified in the seismic profiles, geological (e.g. outcrop mapping, drill hole, geochronology, isotope) and geophysical (e.g. gravity, aeromagnetic, magnetotelluric, passive seismic) data are used to map the crustal boundaries, in map view, away from the seismic profiles. For some of these boundaries, a high level of confidence can be placed on the location, whereas the location of other boundaries can only be considered to have medium or low confidence. In other areas, especially in regions covered by thick sedimentary successions, the locations of some crustal boundaries are essentially unconstrained. </div><div>The ‘Major crustal boundaries of Australia’ map shows the locations of inferred ancient plate boundaries, and will provide constraints on the three dimensional architecture of Australia. It allows a better understanding of how the Australian continent was constructed from the Mesoarchean through to the Phanerozoic, and how this evolution and these boundaries have controlled metallogenesis. It is best viewed as a dynamic dataset, which will need to be refined and updated as new information, such as new seismic reflection data, becomes available.</div><div><br></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>

The National Geochemical Survey of Australia (NGSA) is Australia’s only internally consistent, continental-scale geochemical atlas and dataset (<a href="http://dx.doi.org/10.11636/Record.2011.020">http://dx.doi.org/10.11636/Record.2011.020</a>). The present dataset provides additional geochemical data for Li, Be, Cs, and Rb acquired as part of the Australian Government-funded Exploring for the Future (EFTF) program and in support of the Australian Government’s 2023-2030 Critical Minerals Strategy. The dataset fills a knowledge gap about Li distribution in Australia over areas dominated by transported regolith. The main ‘total’ element analysis method deployed for NGSA was based on making a fused bead using lithium-borate flux for XRF then ICP-MS analysis. Consequently, the samples could not be meaningfully analysed for Li. All 1315 NGSA milled coarse-fraction (<2 mm) top (“TOS”) catchment outlet sediment samples, taken from 0 to 10 cm depth in floodplain landforms, were analysed in the current project following the digestion method that provides near-total concentrations of Li, Be, Cs, and Rb. The samples were analysed by the commercial laboratory analysis service provider Bureau Veritas in Perth using low-level mixed acid (a mixture of nitric, perchloric and hydrofluoric acids) digestion with elements determined by ICP-MS (Bureau Veritas methods MA110 and MA112). The data are reported in the same format as the NGSA dataset, allowing for seamless integration with previously released NGSA data. Further details on the QA/QC procedures as well as data interpretation will be reported elsewhere. This data release also includes four continental-scale geochemical maps for Li, Be, Cs, and Rb built from these analytical data. This dataset, in conjunction with previous data published by NGSA, will be of use to mineral exploration and prospectivity modelling around Australia by providing geochemical baselines for Li, Be, Cs, and Rb, as well as identifying regions of anomalism. Additionally, these data also have relevance to other applications in earth and environmental sciences.

<div>The National Geochemical Survey of Australia (NGSA) is Australia’s only internally consistent, continental-scale geochemical atlas and dataset. The present report presents additional mineralogical data acquired as part of the Heavy Mineral Map of Australia (HMMA) project on the NGSA samples, covering ~81% of Australia. The HMMA project, a collaborative project between Geoscience Australia and Curtin University underpinned by a pilot project establishing its feasibility, is part of the Australian Government-funded Exploring for the Future (EFTF) program.</div><div>All of the 1315 NGSA bottom catchment outlet sediment samples, taken on average from 60 to 80 cm depth in floodplain landforms, were used in the HMMA project. The samples were dried and sieved to a 75-425 µm grainsize fraction, and the contained heavy minerals (HMs; i.e., those with a specific gravity > 2.9 g/cm3) were separated by dense fluids and mounted on cylindrical epoxy mounts. After polishing and carbon-coating, the mounts were subjected to automated mineralogical analysis on a TESCAN® Integrated Mineral Analyzer (TIMA). Using scanning electron microscopy and backscatter electron imaging integrated with energy dispersive X-ray analysis, the TIMA identified 163 unique phases (including ‘Unclassified”) in the NGSA sample set. The dataset, consisting of over 145 million individual mineral grains, was quality controlled and validated by an expert team. The data released here can be visualised, explored and downloaded using a free online, bespoke mineral network analysis (MNA) tool built on a cloud-based platform. Preliminary analysis suggests that zinc minerals and native elements&nbsp;(e.g., native gold and platinum) may be useful in mineral exploration applications. Detailed interpretations of the HMMA dataset will be provided elsewhere. Accompanying this report are data files of TIMA results, a minerals property file, and an atlas of HM distribution maps. </div><div>It is hoped the comprehensive dataset generated by the HMMA project will be of use to mineral exploration and prospectivity modelling around Australia, as well as have other applications in earth and environmental sciences.</div>

<div>Alkaline and related rocks are a relatively rare class of igneous rocks worldwide. Alkaline rocks encompass a wide range of rock types and are mineralogically and geochemically diverse. They are typically though to have been derived by generally small to very small degrees of partial melting of a wide range of mantle compositions. As such these rocks have the potential to convey considerable information on the evolution of the Earth’s mantle (asthenosphere and lithosphere), particularly the role of metasomatism which may have been important in their generation or to which such rocks may themselves have contributed. Such rocks, by their unique compositions and or enriched source protoliths, also have considerable metallogenic potential, e.g., diamonds, Th, U, Zr, Hf, Nb, Ta, REEs. It is evident that the geographic occurrences of many of these rock types are also important, and may relate to presence of old cratons, craton margins or major lithospheric breaks. Finally, many alkaline rocks also carry with them mantle xenoliths providing a snapshot of the lithospheric mantle composition at the time of their emplacement.</div><div><br></div><div>Accordingly, although alkaline and related rocks comprise only a volumetrically minor component of the geology of Australia, they are of considerable importance to studies of lithospheric composition, evolution and architecture and to helping constrain the temporal evolution of the lithosphere, as well as more directly to metallogenesis and mineralisation.</div><div><br></div><div>This contribution presents data on the distribution and geology of Australian alkaline and related rocks of Proterozoic age. Proterozoic alkaline and related rocks are primarily restricted to the western two-thirds of the Australia continent, congruent with the distribution of Proterozoic rocks more generally. Proterozoic alkaline rock units are most abundant in Western Australia and the Northern Territory, with minor occurrences in South Australia, and the western regions of Queensland, New South Wales and Tasmania.</div><div><br></div><div>The report and accompanying GIS document the distribution, age, lithology, mineralogy and other characteristics of these rocks (e.g., extrusive/intrusive, presence of mantle xenoliths, presence of diamonds), as well as references for data sources and descriptions. The report also reviews the nomenclature of alkaline rocks and classification procedures. GIS metadata are documented in the appendices.&nbsp;</div>

<div> A key issue for explorers in Australia is the abundant sedimentary and regolith cover obscuring access to underlying potentially prospective rocks. &nbsp;Multilayered chronostratigraphic interpretation of regional broad line-spaced (~20&nbsp;km) airborne electromagnetic (AEM) conductivity sections have led to breakthroughs in Australia’s near-surface geoscience. &nbsp;A dedicated/systematic workflow has been developed to characterise the thickness of cover and the depth to basement rocks, by delineating contact geometries, and by capturing stratigraphic units, their ages and relationships. &nbsp;Results provide a fundamental geological framework, currently covering 27% of the Australian continent, or approximately 2,085,000&nbsp;km2. &nbsp;Delivery as precompetitive data in various non-proprietary formats and on various platforms ensures that these interpretations represent an enduring and meaningful contribution to academia, government and industry.&nbsp;The outputs support resource exploration, hazard mapping, environmental management, and uncertainty attribution.&nbsp;This work encourages exploration investment, can reduce exploration risks and costs, helps expand search area whilst aiding target identification, and allows users to make well-informed decisions. Presented herein are some key findings from interpretations in potentially prospective, yet in some cases, underexplored regions from around Australia.&nbsp;</div> This abstract was submitted & presented to the 8th International Airborne Electromagnetics Workshop (AEM2023) (https://www.aseg.org.au/news/aem-2023)

<div>In Australia, wide-spread sedimentary basin and regolith cover presents a key challenge to explorers, environmental managers and decision-makers, as it obscures underlying rocks of interest. To address this, a national coverage of airborne electromagnetics (AEM) with a 20&nbsp;km line-spacing is being acquired. This survey is acquired as part of the Exploring for the Future program and in collaboration with state and territory geological surveys. This survey presents an opportunity for regional geological interpretations on the modelled AEM data, helping constrain the characteristics of the near-surface geology beneath the abundant cover, to a depth of up to ~500&nbsp;m.</div><div> The AEM conductivity sections were used to delineate key chronostratigraphic boundaries, e.g. the bases of geological eras, and provide a first-pass interpretation of the subsurface geology. The interpretation was conducted with a high level of data integration with boreholes, potential fields geophysics, seismic, surface geology maps and solid geology maps. This approach led to the construction of well-informed geological interpretations and provided a platform for ongoing quality assurance and quality control of the interpretations and supporting datasets. These interpretations are delivered across various platforms in multidimensional non-proprietary open formats, and have been formatted for direct upload to Geoscience Australia’s (GA) Estimates of Geological and Geophysical Surfaces (EGGS) database, the national repository of multidisciplinary subsurface depth estimates.</div><div> These interpretations have resulted in significant advancements in our understanding of Australia’s near-surface geoscience, by revealing valuable information about the thickness and composition of the extensive cover, as well as the composition, structure and distribution of underlying rocks. Current interpretation coverage is ~110,000 line kilometres of AEM conductivity sections, or an area &gt;2,000,000&nbsp;km2, similar to the area of Greenland or Saudi Arabia. This ongoing work has led to the production of almost 600,000 depth estimate points, each attributed with interpretation-specific metadata. Three-dimensional line work and over 300,000 points are currently available for visualisation, integration and download through the GA Portal, or for download through GA’s eCat electronic catalogue. </div><div> These interpretations demonstrate the benefits of acquiring broadly-spaced AEM surveys. Interpretations derived from these surveys are important in supporting regional environmental management, resource exploration, hazard mapping, and stratigraphic unit certainty quantification. Delivered as precompetitive data, these interpretations provide users in academia, government and industry with a multidisciplinary tool for a wide range of investigations, and as a basis for further geoscientific studies.</div> Abstract submitted and presented at 2023 Australian Earth Science Convention (AESC), Perth WA (https://2023.aegc.com.au/)

<div>The Proterozoic alkaline and related igneous rocks of Australia is a surface geology compilation of alkaline and related igneous rocks of Proterozoic age in Australia. This dataset is one of five datasets, with compilations for Archean, Paleozoic, Mesozoic and Cenozoic alkaline and related igneous rocks already released.</div><div><br></div><div>Geological units are represented as polygon and point geometries and, are attributed with information that includes, but is not limited to, stratigraphic nomenclature and hierarchy, age, lithology, composition, proportion of alkaline rocks, body morphology, unit expression, emplacement type, presence of mantle xenoliths and diamonds, and primary data source. Source data for the geological unit polygons provided in Data Quality LINEAGE. Geological units are grouped into informal geographic “alkaline provinces”, which are represented as polygon geometries, and attributed with information similar to that provided for the geological units.</div>

<div>Geoscience Australia has a large holding of surface sediment samples, such as stream and overbank sediments, from geochemical surveys conducted over more than 50 years across the Australian continent. Geochemical data from these surface materials are of national importance as they can contribute significantly to establishing geochemical environmental baselines and their use in land management, as well as aiding in the discovery of new mineral deposits. Samples from these legacy surveys provide valuable insights into areas of Australia that are remote, difficult to access, or have since been developed. The age of a large number of these surveys, however, means that the original results included data for a&nbsp;smaller range of chemical elements, typically with poorer analytical precision and accuracy than those of modern surveys. This small range of chemical elements also typically doesn’t include important elements for modern use, such as critical minerals (i.e. Co, Bi, REEs), which are increasing in their importance. As part of Geoscience Australia’s Exploring for the Future program, a collection of over 9000 samples from these surveys was reanalysed using modern analytical techniques for a&nbsp;suite of 60 chemical elements. These samples cover several regions within Australia, including Kakadu, Cape York, the Mount Isa region, and near the Canberra region. The new analytical data maximise the value of the historical geochemical surveys and will provide new insights into the mineral potential of these regions and improve the quality of geochemical environmental baselines.&nbsp;</div><div><br></div><div>This data release includes: 1) information on the surveys and their samples; 2) quality assurance results; 3) a discussion of sample preparation and analytical methods used; 4) results for total content geochemistry (XRF and LA-ICP-MS); and 5) individual element maps for each of the regions for preliminary interpretation of the data.</div><div><br></div><div>Acquisition and release of this dataset forms part of a larger program aimed at creating a levelled geochemical baseline for the whole Australia (Main and Champion, 2020).</div>