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  • The Mineral Potential web service provides access to digital datasets used in the assessment of mineral potential in Australia. The service includes maps showing the potential for sediment-hosted base metal mineral systems in Australia.

  • <div>Long-period magnetotelluric (MT) data from the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP), collected as part of Geoscience Australia’s Exploring for the Future program with contributions from the Northern Territory Geological Survey and the Geological Survey of Queensland, provide important first-order information for resolving large-scale lithospheric architecture and identifying the broad footprint of mineral systems in northern Australia. Large-scale crust/mantle conductivity anomalies map pathways of palaeo-fluid migration which is an important element of several mineral systems. For example, the Carpentaria conductivity anomaly east of Mount Isa and the Croydon, Georgetown to Greenvale conductivity anomaly are highly conductive lithospheric-scale structures, and show spatial correlations with major suture zones and known mineral deposits. These results provide evidence that some mineralisation occurs at the gradient of or over highly conductive structures at lower crustal and lithospheric mantle depths, which may represent fertile source regions for mineral systems. These observations provide a powerful means of highlighting prospective greenfield areas for mineral exploration in under-explored and covered regions.</div><div><br></div><div>Higher resolution scale-reduction MT surveys refine the geometry of some conductive anomalies from AusLAMP data, and investigate whether these deep conductivity anomalies link to the near surface. These links may act as conduits for crustal/mantle scale fluid migration to the upper crust, where they could form mineral deposits. For example, data reveals a favourable crustal architecture linking the deep conductivity anomaly or fertile source regions to the upper crust in the Cloncurry region. In addition, high-frequency MT data help to characterise cover and assist with selecting targets for drilling and improve the understanding of basement geology.</div><div><br></div><div>These results demonstrate that integration of multi-scale MT surveys is an effective approach for mapping lithospheric-scale features and selecting prospective areas for mineral exploration in covered terranes with limited geological knowledge.</div><div><br></div><div>Some models in this presentation were produced on the National Computational Infrastructure, which is supported by the Australian government. Abstract presented to the Australian Institute of Geoscientists – ALS Friday Seminar Series: Geophysical and Geochemical Signatures of Queensland Mineral Deposits October 2023 (https://www.aig.org.au/events/aig-als-friday-seminar-series-geophysical-and-geochemical-signatures-of-qld-mineral-deposits/)

  • The Mineral Potential web service provides access to digital datasets used in the assessment of mineral potential in Australia. The service includes maps showing the potential for sediment-hosted base metal mineral systems in Australia.

  • <div>The production of rare earth elements is critical for the transition to a low carbon economy. Carbonatites (&gt;50% carbonate minerals) are one of the most significant sources of rare earth elements (REEs), both domestically within Australia, as well as globally. Given the strategic importance of critical minerals, including REEs, for the Australian national economy, a mineral potential assessment has been undertaken to evaluate the prospectivity for carbonatite-related REE (CREE) mineralisation in Australia. CREE deposits form as the result of lithospheric- to deposit-scale processes that are spatially and temporally coincident.</div><div><br></div><div>Building on previous research into the formation of carbonatites and their related REE mineralisation, a mineral system model has been developed that incorporates four components: (1) source of metals, fluids, and ligands, (2) energy sources and fluid flow drivers, (3) fluid flow pathways and lithospheric architecture, and (4) ore deposition. This study demonstrates how national-scale datasets and a mineral systems-based approach can be used to map the mineral potential for CREE mineral systems in Australia.</div><div><br></div><div>Using statistical analysis to guide the feature engineering and map weightings, a weighted index overlay method has been used to generate national-scale mineral potential maps that reduce the exploration search space for CREE mineral systems by up to ∼90%. In addition to highlighting regions with known carbonatites and CREE mineralisation, the mineral potential assessment also indicates high potential in parts of Australia that have no previously identified carbonatites or CREE deposits.</div><div><br></div><div><b>Citation: </b>Ford, A., Huston, D., Cloutier, J., Doublier, M., Schofield, A., Cheng, Y., and Beyer, E., 2023. A national-scale mineral potential assessment for carbonatite-related rare earth element mineral systems in Australia, <i>Ore Geology Reviews</i>, V. 161, 105658. https://doi.org/10.1016/j.oregeorev.2023.105658</div>

  • Maps showing the potential for sediment-hosted base metal mineral systems in Australia. Each of the mineral potential maps is a synthesis of four component layers: sources of metals, energy drivers, lithospheric architecture, and depositional gradients, using a weighted sum to produce the final mineral potential map for the mineral system. Uncertainty maps are provided in conjunction with each of the mineral potential maps that represent the availability of data coverage over Australia for the selected combination of input maps. Uncertainty values range between 0 and 1, with higher uncertainty values being located in areas where more input maps are missing data or have unknown values. The set of input maps used to generate the mineral potential maps is provided along with an assessment criteria table that contains information on the map creation.

  • <div>Mineral prospectivity studies seek to map evidence of mineral system activity, with the aim of informing mineral exploration decisions and guiding exploration in the face of uncertainty. These studies leverage the growing volumes of information that are available to characterise the lithosphere by compiling covariate (or feature) grids that represent key mineral system ingredients. Previous studies have been categorised as either “knowledge-driven” or “data-driven” approaches depending on whether these grids are integrated via expert elicitation or by the empirical relationship to known mineralisation, respectively. However, to our knowledge, the underlying modelling framework and assumptions have not been systematically reviewed to understand how choices in the approach to the problem influence modelling outcomes. Here we show the broad mathematical equivalence in these approaches and highlight the limitations inherent when optimising to minimise misfit in potentially under-determined problems. We argue that advances in mineral prospectivity are more likely to be driven by careful consideration of the model selection problem. Focusing effort on model selection will not only drive more robust mineral prospectivity predictions but may also simultaneously refine our understanding of key mineral system processes. To build on these results, we present the Mineral Potential Toolkit; a software repository to facilitate feature engineering, statistical appraisal, and quantitative prospectivity modelling. The toolkit enables a novel approach that combines the best aspects of previous methods. Abstract presented to the 26th World Mining Congress 2023 (https://wmc2023.org/)

  • Magnetotelluric (MT) data allow geoscientists to investigate the link between mineralisation and lithospheric-scale features and processes. In particular, the highly conductive structures imaged by MT data appear to map the pathways of large-scale palaeo-fluid migration, which is an important element of several mineral systems. New data were collected as part of the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) under Geoscience Australia Exploring for the Future (EFTF) program in northern Australian. We use this dataset to demonstrate that the MT method is a valuable tool for mapping lithospheric-scale features and for selecting prospective areas for mineral exploration. Our results image a number of major conductive structures at depths up to ~200 km or deeper in the survey region, for example, the Carpentaria Conductivity Anomaly in east of Mount Isa; and the Tanami Conductive Anomaly along the Willowra Suture Zone. These significant anomalies are lithospheric- scale highly conductive structures, and show spatial correlations with major suture zones and known mineral deposits. These results provide important first-order information for lithospheric architecture and possible large footprint of mineral systems. Large-scale crustal/mantle conductivity anomalies mapping fluid pathways associated with major sutures/faults may have implications for mineral potential. These results provide evidence that some mineralisation occurs at the gradient of or over highly conductive structures at lower crustal and lithospheric mantle depths. These observations provide a powerful means of highlighting greenfields for mineral exploration in under-explored and covered regions.

  • <div>The production of rare earth elements (REEs) is critical to the global transition to a low carbon economy. Carbonatites represent a significant source of REEs, both domestically within Australia, as well as globally. Given their strategic importance for the Australian economy, a national mineral potential assessment has been undertaken as part of the Exploring for the Future program at Geoscience Australia to evaluate the potential for carbonatite-related REE (CREE) mineral systems. Rather than aiming to identify individual carbonatites and/or CREE deposits, the focus of the mineral potential assessment is to delineate prospective belts or districts within Australia that indicate the presence of favourable criteria, particularly in terms of lithospheric architecture, that may lead to the formation of a CREE mineral system.</div><div><br></div><div>This study demonstrates how national-scale multidisciplinary precompetitive geoscience datasets can be integrated using a hybrid methodology that incorporates robust statistical analysis with mineral systems expertise to predictively map areas that have a higher geological potential for the formation of CREE mineral systems and effectively reduce the exploration search space. Statistical evaluation of the relationship between different mappable criteria that represent spatial proxies for mineral system processes and known carbonatites and CREE deposits has been undertaken to test previously published hypotheses on how to target CREE mineral systems at a broad-scale. The results confirm the relevance of most criteria in the Australian context, while several new criteria such as distance to large igneous province margins and distance to magnetic worms have also been shown to have a strong correlation with known carbonatites and CREE deposits. Using a hybrid knowledge- and data-driven mineral potential mapping approach, the mineral potential map predicts the location of known carbonatite and CREE deposits, while also demonstrating additional areas of high prospectivity in regions with no previously identified carbonatites or CREE mineralisation.</div> Presented at the AusIMM Critical Minerals Conference 2023.

  • <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>Sediment-hosted copper (Cu) mineral systems are important sources of base metals and critical minerals such as cobalt that are vital to delivering Australia’s low-carbon economy. In Australia, sediment-hosted Cu resources account for ~11% of the total Cu resources. Given their significance to the Australian economy, national-scale mineral potential models for sediment-hosted Cu have been developed. In addition to the potential for sediment-hosted Cu mineralisation, the uncertainty related to data availability has been examined. Three mineral potential</div><div>models derived from the combination of two mineral systems have been derived from a large volume of precompetitive geoscience data combined with mineral systems expertise, each using a different combination of input maps to assess the influence of incomplete data on the results. The mineral potential models successfully predict the location of major sediment-hosted stratiform Cu and Mount Isa-type Cu deposits while highlighting new areas of elevated prospectivity in under-explored regions of Australia, reducing the exploration search space</div><div>by up to ~84%.</div>