Remotely sensed datasets provide fundamental information for understanding the chemical, physical and temporal dynamics of the atmosphere, lithosphere, biosphere and hydrosphere. Satellite remote sensing has been used extensively in mapping the nature and characteristics of the terrestrial land surface, including vegetation, rock, soil and landforms, across global to local-district scales. With the exception of hyper-arid regions, mapping rock and soil from space has been problematic because of vegetation that either masks the underlying substrate or confuses the spectral signatures of geological materials (i.e. diagnostic mineral spectral features), making them difficult to resolve. As part of the Exploring for the Future program, a new barest earth Landsat mosaic of the Australian continent using time-series analysis significantly reduces the influence of vegetation and enhances mapping of soil and exposed rock from space. Here, we provide a brief background on geological remote sensing and describe a suite of enhanced images using the barest earth Landsat mosaic for mapping surface mineralogy and geochemistry. These geological enhanced images provide improved inputs for predictive modelling of soil and rock properties over the Australian continent. In one case study, use of these products instead of existing Landsat TM band data to model chromium and sodium distribution using a random forest machine learning algorithm improved model performance by 28–46%. <b>Citation:</b> Wilford, J. and Roberts, D., 2020. Enhanced barest earth Landsat imagery for soil and lithological modelling. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.

<div>The National Geochemical Survey of Australia (NGSA) is Australia’s only internally consistent, continental-scale geochemical atlas and dataset. The present dataset contains additional mineralogical data obtained on NGSA samples selected from the Barkly-Isa-Georgetown (BIG) region of northeastern Australia for the second partial data release of the Heavy Mineral Map of Australia (HMMA) project. 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>One-hundred and eighty eight NGSA sediment samples were selected from the HMMA project within the EFTF’s BIG polygon plus an approximately one-degree buffer. The samples were taken on average from 60 to 80 cm depth in floodplain landforms, dried and sieved to a 75-430 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 151 different HMs in the BIG area. The dataset, consisting of over 18 million individual mineral grains, was quality controlled and validated by an expert team. The data released here can be visualised, explored and downloaded using an online, bespoke mineral network analysis (MNA) tool built on a cloud-based platform. Preliminary analysis suggests that copper minerals cuprite and chalcopyrite may be indicative of base-metal/copper mineralisation in the area. Accompanying this report are two data files of TIMA results, and a minerals vocabulary file. </div><div>When completed in 2023, it is hoped the HMMA project will positively impact mineral exploration and prospectivity modelling around Australia, as well as have other applications in earth and environmental sciences.</div>

<div>This report presents the results of petrographic and X-ray Diffraction analysis undertaken by Microanalysis Australia under contract to Geoscience Australia, on rock samples collected from selected drill holes across the Proterozoic Birrindudu Basin and underlying metamorphic basement.</div><div><br></div>

<b>Please Note:</b> The data related to this Abstract can be obtained by contacting <a href = "mailto: clientservices@ga.gov.au">Manager Client Services</a> and quoting Catalogue number 144231. The data are arranged by regions, so please download the Data Description document found in the Downloads tab to determine your area of interest. Remotely sensed datasets provide fundamental information for understanding the chemical, physical and temporal dynamics of the atmosphere, lithosphere, biosphere and hydrosphere. Satellite remote sensing has been used extensively in mapping the nature and characteristics of the terrestrial land surface, including vegetation, rock, soil and landforms, across global to local-district scales. With the exception of hyper-arid regions, mapping rock and soil from space has been problematic because of vegetation that either masks the underlying substrate or confuses the spectral signatures of geological materials (i.e. diagnostic mineral spectral features), making them difficult to resolve. As part of the Exploring for the Future program, a new barest earth Landsat mosaic of the Australian continent using time-series analysis significantly reduces the influence of vegetation and enhances mapping of soil and exposed rock from space. Here, we provide a brief background on geological remote sensing and describe a suite of enhanced images using the barest earth Landsat mosaic for mapping surface mineralogy and geochemistry. These geological enhanced images provide improved inputs for predictive modelling of soil and rock properties over the Australian continent. In one case study, use of these products instead of existing Landsat TM band data to model chromium and sodium distribution using a random forest machine learning algorithm improved model performance by 28–46%.

Large-scale storage of commercially produced hydrogen worldwide is presently stored in salt caverns. Through the Exploring for the Future program, Geoscience Australia is identifying and mapping salt deposits in Australia that may be suitable for hydrogen storage. The Boree Salt in the Adavale Basin of central Queensland is the only known thick salt accumulation in eastern Australia, and represent potentially strategic assets for underground hydrogen storage. The Boree Salt consists predominantly of halite and can be up to 555 m thick in some wells. Geoscience Australia contracted CSIRO to conduct analyses four Boree Salt whole cores extracted from Boree 1 and Bury 1 wells. The tests were carried out to determine the seal capacity (mercury injection capillary pressure - MICP), mineralogy (X-ray diffraction - XRD), and inorganic geochemistry of the cores. The entire core sections were scanned using X-ray CT images. In addition, four plugs were taken from the cores and tested for dry bulk density, grain density, gas porosity, and permeability. Two plugs underwent ultra-low permeability tests. The MICP test suggests that the Boree Salt is a competent seal for hydrogen storage. Mineralogy testing (XRD) revealed that the Boree Salt samples primarily comprise halite (96.5%), minor anhydrite (1.32%) and dolomite (1.65%) with traces of quartz, calcite, sylvite and cristobalite. Inorganic geochemistry results show sodium (Na; 55.4% average) is the most abundant element. Further tests, such as the creep test, in-situ seal capacity test, and leaching tests, are required to determine the suitability of the Boree Salt for underground hydrogen storage. Disclaimer: Geoscience Australia has tried to make the information in this product as accurate as possible. However, it does not guarantee that the information is totally accurate or complete. Therefore, you should not solely rely on this information when making a commercial decision. This dataset is published with the permission of the CEO, Geoscience Australia.

<div>Although heavy mineral exploration techniques have been successfully used as exploration vectors to ore deposits around the world, exploration case studies and pre-competitive datasets relevant to Australian conditions are relatively limited. The Heavy Mineral Map of Australia (HMMA) project is a novel analytical campaign to determine the abundance and distribution of heavy minerals (SG>2.9 g/cc) in 1315 floodplain sediment samples collected from catchments across Australia during Geoscience Australia’s National Geochemical Survey of Australia (NGSA) project. Archived NGSA samples, which originated from, on average, 60 to 80 cm depth in floodplain landforms, were sub-sampled and subjected to dense media separation and automated SEM-EDS analysis in the John de Laeter Centre at Curtin University. Mineral assay data from all 1315 drainage samples will be publicly released by the end of 2023. </div><div><br></div><div>An initial data package released in August 2022 contains mineralogical assay data for 223 samples from the Darling–Curnamona–Delamerian (DCD) region of south-eastern Australia. That package identified over 140 heavy minerals from 29 million individual mineral observations. The number of mineral observations generated during the project required development of a novel Mineral Network Analysis (MNA) tool to allow end users to discover, visualise and interpret mineral co-occurrence relationships, potentially useful in exploration vectoring and targeting. The MNA tool can also be used to rapidly search the heavy mineral database to locate observations of potential economic significance. The co-occurrence of Zn-minerals indicative of high-grade metamorphism of base metal mineralisation (e.g., gahnite (Zn-spinel), ecandrewsite (Zn-ilmenite) and zincostaurolite (Zn-aluminosilicate)) from the region surrounding Broken Hill demonstrated the utility of the method. Zn-mineral co-occurrences not associated with known mineralisation were also noted and may represent targeting opportunities. </div><div><br></div><div>Heavy mineral data from parts of Queensland are scheduled for a separate public release in December 2022 and will be presented at the conference.&nbsp;</div> This Abstract was submitted/presented to the 2023 Australian Exploration Geoscience Conference 13-18 Mar (https://2023.aegc.com.au/)

Brumbys 1 was an appraisal well drilled and cored through Brumbys Fault at the CO2CRC Otway International Test Centre in 2018. The Otway Project is located in South West Victoria, on private farming property approximately 35 km southeast of Warrnambool and approximately 10 km northwest of the town of Peterborough. Total measured depth was 126.6 m (80 degrees). Sonic drilling enabled excellent core recovery and the borehole was completed as a groundwater monitoring well. Brumbys 1 cores through the upper Hesse Clay, Port Campbell Limestone and extends into the Gellibrand Marl. This dataset compiles the extensive analysis undertaken on the core. Analysis includes: Core log; Foram Analysis; Paleodepth; % Carbonate (CaCO3); X-Ray Fluorescence Spectrometry (XRF); Inductively Coupled Plasma Mass Spectrometry (ICP-MS); X-Ray Diffraction (XRD); Grain Size; Density; Surface Area Analysis (SAA); Gamma. Samples were taken at approximately 1-2 m intervals.

<div>Heavy minerals (HMs) are those with a specific gravity greater than 2.9 g/cc (e.g., anatase, zircon). They have been used successfully in mineral exploration programs outside Australia for decades [1 and refs therein]. Individual HMs and combinations, or co-occurrence, of HMs can be characteristic of lithology, degree of metamorphism, alteration, weathering or even mineralisation. These are termed indicator minerals, and have been used in exploration for gold, diamonds, mineral sands, nickel-copper, platinum group elements, volcanogenic massive sulfides, non-sulfide zinc, porphyry copper-molybdenum, uranium, tin-tungsten, and rare earth elements mineralization. Although there are proprietary HM sample assets held by industry in Australia, no extensive public-domain dataset of the natural distribution of HMs across the continent currently exists.</div><div> We describe a vision for a national-scale heavy mineral (HM) map generated through automated mineralogical identification and quantification of HMs contained in floodplain sediments from large catchments covering most of Australia [1]. These samples were collected as part of the National Geochemical Survey of Australia (NGSA; www.ga.gov.au/ngsa) and are archived in Geoscience Australia’s rock store. The composition of the sediments can be assumed to reflect the dominant rock and soil types within each catchment (and potentially those upstream), with the generally resistant HMs largely preserving the mineralogical fingerprint of their host protoliths through the weathering-transport-deposition cycle. </div><div> Underpinning this vision is a pilot project, focusing on a subset of NGSA to demonstrate the feasibility of the larger, national-scale project. Ten NGSA sediment samples were selected and both bulk and HM fractions were analysed for quantitative mineralogy using a Tescan® Integrated Mineral Analyzer (TIMA) at the John de Laeter Centre, Curtin University (Figure 1). Given the large and complex nature of the resultant HM dataset, we built a bespoke, cloud-based mineral network analysis (MNA) tool to visualise, explore and discover relationships between HMs, as well as between them and geological setting or mineral deposits. The pilot project affirmed our expectations that a rich and diverse mineralogical ecosystem will be revealed by expanding HM mapping to the continental scale. </div><div> A first partial data release in 2022 was the first milestone of the Heavy Mineral Map of Australia (HMMA) project. The area concerned is the Darling-Curnamona-Delamerian region of southeastern Australia, where the richly endowed Broken Hill mineral province lies. Here, we identified over 140 heavy minerals from 29 million individual mineral observations in 223 sediment samples. Using the MNA tool, one can quickly identify interesting base metal mineral associations and their spatial distributions (Figure 2).</div><div> We envisage that the Heavy Mineral Map of Australia and the MNA tool will contribute significantly to mineral prospectivity analysis and modelling in Australia, particularly for technology critical elements and their host minerals, which are central to the global economy transitioning to a more sustainable, decarbonised paradigm.</div><div><br></div>Figure 1. Distribution map of ten selected heavy minerals in the heavy mineral fractions of the ten NGSA pilot samples (pie charts), overlain on Australia’s geological regions (variable colors) [2]). Map projection: Albers equal area.</div><div><br></div><div>Figure 2. Graphical user interface for the Geoscience Australia MNA cloud-based visualization tool for the DCD project (https://geoscienceaustralia.shinyapps.io/HMMA-MNA/) showing the network for Zn minerals with the gahnite subnetwork highlighted (left) and the map of gahnite distribution (right).</div><div> <strong>References</strong></div><div>[1] Caritat et al., 2022, Minerals, 12(8), 961. https://doi.org/10.3390/min12080961 </div><div>[2] Blake &amp; Kilgour, 1998, Geosci Aust. https://pid.geoscience.gov.au/dataset/ga/32366 </div><div><br></div>This Abstract was submitted/presented to the 2022 Mineral Prospectivity and Exploration Targeting (MinProXT 2022) webinar, Freiburg, Germany, 01 - 03 November (www.minproxt.com)

Heavy minerals (HMs) are minerals with a specific gravity greater than 2.9 g/cm3. They are commonly highly resistant to physical and chemical weathering, and therefore persist in sediments as lasting indicators of the (former) presence of the rocks they formed in. The presence/absence of certain HMs, their associations with other HMs, their concentration levels, and the geochemical patterns they form in maps or 3D models can be indicative of geological processes that contributed to their formation. Furthermore trace element and isotopic analyses of HMs have been used to vector to mineralisation or constrain timing of geological processes. The positive role of HMs in mineral exploration is well established in other countries, but comparatively little understood in Australia. Here we present the results of a pilot project that was designed to establish, test and assess a workflow to produce a HM map (or atlas of maps) and dataset for Australia. This would represent a critical step in the ability to detect anomalous HM patterns as it would establish the background HM characteristics (i.e., unrelated to mineralisation). Further the extremely rich dataset produced would be a valuable input into any future machine learning/big data-based prospectivity analysis. The pilot project consisted in selecting ten sites from the National Geochemical Survey of Australia (NGSA) and separating and analysing the HM contents from the 75-430 µm grain-size fraction of the top (0-10 cm depth) sediment samples. A workflow was established and tested based on the density separation of the HM-rich phase by combining a shake table and the use of dense liquids. The automated mineralogy quantification was performed on a TESCAN® Integrated Mineral Analyser (TIMA) that identified and mapped thousands of grains in a matter of minutes for each sample. The results indicated that: (1) the NGSA samples are appropriate for HM analysis; (2) over 40 HMs were effectively identified and quantified using TIMA automated quantitative mineralogy; (3) the resultant HMs’ mineralogy is consistent with the samples’ bulk geochemistry and regional geological setting; and (4) the HM makeup of the NGSA samples varied across the country, as shown by the mineral mounts and preliminary maps. Based on these observations, HM mapping of the continent using NGSA samples will likely result in coherent and interpretable geological patterns relating to bedrock lithology, metamorphic grade, degree of alteration and mineralisation. It could assist in geological investigations especially where outcrop is minimal, challenging to correctly attribute due to extensive weathering, or simply difficult to access. It is believed that a continental-scale HM atlas for Australia could assist in derisking mineral exploration and lead to investment, e.g., via tenement uptake, exploration, discovery and ultimately exploitation. As some HMs are hosts for technology critical elements such as rare earth elements, their systematic and internally consistent quantification and mapping could lead to resource discovery essential for a more sustainable, lower-carbon economy.

<div>The lookbook accompanies a loan of Australian critical mineral samples provided by Geoscience Australia for display at the Australian Embassy in Washington DC, United States.&nbsp; It contains information about each of the samples, including their provenance, mineral or rock name, and the critical mineral they contain.</div>