GEOLOGY
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The Exploring for the Future Program (EFTF) is a $100.5 million four year, federally funded initiative to better characterise the mineral, energy and groundwater potential of northern Australia. A key focus area of the initiative is the South Nicholson region, situated across the Northern Territory and Queensland border. The South Nicholson region is located between two highly prospective provinces, the greater McArthur Basin in the Northern Territory, the Lawn Hill Platform and the Mount Isa Province in Queensland–Northern Territory, which both have demonstrated hydrocarbon and base metal resources. In contrast, the South Nicholson region is not well understood geologically, is mostly undercover with limited well data, and prior to EFTF contained limited seismic coverage. Re–Os analyses in this study were undertaken to complement seismic data, U–Pb geochronology and geochemistry data to better understand the geological evolution and resource potential of the South Nicholson region. Five organic carbon bearing sedimentary samples from drillholes BMR Ranken 1, NTGS00/1, DDH 83/1 and DDH 83/4 located across the South Nicholson region were analysed for whole rock Re–Os. The aim of the analyses was to better constrain the depositional age of basin units in the region, and to potentially provide insights into the timing of post-depositional processes such as fluid events and hydrocarbon generation and/or migration. Samples belong to the Mesoproterozoic South Nicholson Group, Paleoproterozoic Fickling and McNamara groups, and the Neoproterozoic to Devonian Georgina Basin. Samples were analysed at the University of Alberta, Canada.
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This double-sided A4 flyer promotes EFTF chronostratigraphic work in the NT, as well as the EFTF newsletter
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This Tasmania Basin dataset contains descriptive attribute information for the areas bounded by the relevant spatial groundwater feature in the associated Hydrogeology Index map. Descriptive topics are grouped into the following themes: Location and administration; Demographics; Physical geography; Surface water; Geology; Hydrogeology; Groundwater; Groundwater management and use; Environment; Land use and industry types; and Scientific stimulus. The Late Carboniferous to Late Triassic Tasmania Basin covers approximately 30,000 square kilometres of onshore Tasmania. The basin contains up to 1500 m of mostly flat-lying sedimentary rocks, and these are divided into two distinct lithostratigraphic units, the Lower and the Upper Parmeener Supergroup. The Lower Parmeener Supergroup comprises Late Carboniferous to Permian rocks that mainly formed in marine environments. The most common rock types in this unit are mudstone, siltstone and sandstone, with less common limestone, conglomerate, coal, oil shale and tillite. The Upper Parmeener Supergroup consists predominantly of non-marine rocks, typically formed in fluvial and lacustrine environments. Common rock types include sandstone, siltstone, mudstone and minor basalt layers. Post-deposition the rocks of the Parmeener Supergroup experienced several major geological events, including the widespread intrusion of tholeiitic dolerite magma during the Middle Jurassic.
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Australia's Identified Mineral Resources is an annual national assessment that takes a long-term view of Australian mineral resources likely to be available for mining. The assessment also includes evaluations of long-term trends in mineral resources, world rankings, summaries of significant exploration results and brief reviews of mining industry developments.
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The Geoscience Australia Structural Measurements Database contains field measurements of geological structure features such as bedding, foliation, lineation, faults and folds from field sites, measured sections, and boreholes. The database is delivered as a layer in Geoscience Australia's "Geological Field Sites, Samples and Observations" web service.
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Earthquake Environmental Effects (EEEs) identified in the source region of the 20th May 2016 intraplate moment magnitude (Mw) 6.1 Petermann earthquake in Central Australia are described and classified using the Environmental Seismic Intensity (ESI-07) scale. EEEs include surface rupture, ground fissures and cracks, vegetation damage, rockfalls, and displaced (jumped) bedrock fragments. The maximum ESI intensity derived from EEEs is X, consistent with previous observations from some moderate Mw crustal earthquakes. Maximum ESI isoseismals correlate with the location of the surface rupture rather than epicentre area due to the dipping geometry of the reverse source fault. ESI isoseismals encompass a larger area of the hanging-wall than the footwall, indicating stronger ground motions on the hanging-wall due to increased proximity to the rupture source and ground motion amplification effects. The maximum areal extent of secondary (seismic shaking-induced) EEEs (300 km2) is significantly smaller than expected using the published ESI-07 scale (approx. 5000 km2). This relates to the low topographic relief and relatively homogeneous bedrock geology of the study region, which (i) reduced the potential for site response amplification of strong ground motions, and (ii) reduced the susceptibility of the landscape to EEE such as landsliding and liquefaction. Erosional degradation of the observed EEE features and decreasing confidence with which they can be uniquely attributed to a seismic origin with increasing time since the earthquake highlight challenges in using many of the natural features observed herein to characterise the locations and attributes of paleo-earthquakes.
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The importance of critical minerals and the need to expand and diversify critical mineral supply chains has been endorsed by the Federal governments of Australia, Canada, and the United States. The geoscience organizations of Geoscience Australia, the Geological Survey of Canada and the U.S. Geological Survey have created the Critical Minerals Mapping Initiative to build a diversified critical minerals industry in Australia, Canada, and the United States by developing a better understanding of known critical mineral resources, determining geologic controls on critical mineral distribution for deposits currently producing byproducts, identifying new sources of supply through critical mineral potential mapping and quantitative mineral assessments, and promoting critical mineral discovery in all three countries.
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<div>Alkaline igneous and related rocks are recognised as a significant source of the critical minerals essential for Australia’s transition to net-zero. Understanding these small but economically significant group of poorly mapped rocks is essential for identifying their resource potential. The Australian Alkaline Rocks Atlas aims to capture all known occurrences of these volumetrically minor, but important, igneous rocks in a national compilation, to aid understanding of their composition, distribution and age at the continental scale. The Atlas, comprises five, stand-alone data packages covering the Archean, Proterozoic, Paleozoic, Mesozoic and Cenozoic eras. Each data package includes a GIS database and detailed accompanying report that informs alkaline rock nomenclature, classification procedures, individual units and their grouping into alkaline provinces based on common age, characteristics and inferred genesis. The Alkaline Rocks Atlas will form a foundation for more expansive research on related mineral systems and their corresponding economic potential being undertaken as part of the EFTF program. To illustrate the use of the Alkaline Rocks Atlas, a mineral potential assessment using a subset of the Atlas has been undertaken for carbonatite-related rare earth element mineral systems that aims to support mineral exploration and land-use decision making that aims to support mineral exploration and land-use decision making.</div>
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Hydrothermal magnetite from the Starra iron oxide‑copper gold (IOCG) deposit in northwest Queensland, Australia, records a gradual decrease in V, Ni, Cr, and Mn that correlates with the transition from early, amphibole-biotite-magnetite dominant alteration to late, chlorite-quartz-hematite-dominated alteration assemblages. The observed systematic change in multivariate elements in magnetite is interpreted to indicate an increase in fO2 during the main Cu(Au) mineralization. We suggest that variations in the V, Ni, and Cr contents of magnetite at Starra indicate either a primary magmatic fluid source or the leaching of mafic rocks by fluids during early albitization. Late silician magnetite contained in ankerite veins that crosscut the pre-existing alteration assemblages in the hanging wall to the Starra 222 ore body is likely the result of a second mineralization phase, which contributed additional metals to the Starra ore bodies. Existing data on magnetite chemistry from several IOA, IOCG, Fe, and Fe-W skarn deposits show that the ratio of V to Ga discriminates the various ore types effectively. Skarn deposits are separated from IOA and IOCG by lower concentrations of V, Ni, and Cr, suggesting a more primitive fluid source or the precipitation of magnetite at distinct physicochemical conditions than IOA and IOCG deposits. Magnetite from IOA deposits exhibits a consistently elevated V concentration whereas magnetite from Fe(–– W) skarn records an increase in V concentration with the evolution of the system. A pronounced decrease in the V contents of magnetite associated with Cu Au mineralization at Starra is interpreted as a change in redox conditions from reduced to oxidized at the time of mineralization. Such variations are also observed in other IOCG deposits. We propose that systematic decreases in V concentration in magnetite during the paragenetic evolution of the host mineral system is a diagnostic indicator for Cu(Au) mineralization in IOCG deposits, and as such, it may be used as a proxy for Cu-Au exploration, if the paragenetic context of magnetite is well constrained. <b>Citation:</b> Max Hohl, Jeffrey A. Steadman, Jonathan Cloutier, Shaun L.L. Barker, Ivan Belousov, Karsten Goemann, David R. Cooke, Trace element systematics of magnetite from the Starra iron oxide‑copper gold deposits reveals early fluid conditions characteristic for Cu mineralization, <i>Chemical Geology</i>, Volume 648, 2024, 121960, ISSN 0009-2541, https://doi.org/10.1016/j.chemgeo.2024.121960
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Sphalerite is the main Zn ore mineral and is the primary source of Cd, Ge and In and a minor source of Ga. Owing to a shift from fossil fuel to renewable energy sources, these four minor elements have progressively become more important to the economy. Despite this, resources of Cd, Ga, Ge and In are rarely reported as these metals are not considered material to the economics of resource development. As a result, the distribution of these elements between and within deposits is poorly known, and national and international resources are largely unreported. Following previous studies, we have compiled analytical data for Cd, Ga, Ge and In from sphalerite and used global and local ore geochemical datasets to assess geochemical controls on the concentration of these elements in Zn deposits. Our results are similar to previous studies and suggest that lower-temperature deposits are enriched in Ge whereas higher-temperature deposits are enriched in In. However, modelling of hydrothermal geochemistry indicates other factors are important in concentrating these metals. In particular, the oxidation state of the fluid (oxidised versus reduced) and the depositional mechanisms also have a strong influence in Ga, Ge and In enrichment. Reduction of oxidised fluids is particularly effective in depositing Ge, whereas cooling very effectively deposits In and, in some cases, Ge. As a consequence, some higher-temperature deposits (e.g. high sulfidation epithermal and some volcanic-hosted massive sulfide) deposits can be Ge-enriched, and some lower-temperature deposits (e.g. siliciclastic-carbonate shale-hosted deposits) can be enriched in In. Using the existing ore geochemical data and calculated characteristic Ge/Zn and In/Zn ratios, indicative estimates have been made on the endowment of Australian Zn deposits of Ge and In. These estimates highlight the potential of the North Australian Zinc Belt for Ge and for VHMS deposits for In. Although there is a large amount of uncertainty in the estimates, they are indicative of the potential for these metals in Australia. <b>Citation:</b> Huston, D. L., & Bastrakov, E. (2024). Germanium, indium, gallium and cadmium in zinc ores: a mineral system approach. <i>Australian Journal of Earth Sciences</i>, 71(8), 1125–1155. https://doi.org/10.1080/08120099.2024.2423772