As global metal demands are increasing whilst new discoveries are declining, the magnetotelluric (MT) technique has shown promise as an effective technique to aid mineral systems mapping. Several case studies have shown a spatial correlation between mineral deposits and conductors, with some showing that resistivity models derived from MT are capable of mapping mineral systems from the lithosphere to deposit scale. However, until now, the statistical significance of such correlations has not been demonstrated and therefore hindered robust utilization of MT data in mineral potential assessments. Here we quantitatively analyze resistivity models from Australia, the United States of America (USA), South America and China and demonstrate that there is a statistically-significant correlation between upper mantle conductors and porphyry copper deposits, and between mid-crustal conductors and orogenic gold deposits. Volcanic hosted massive sulfide deposits show significant correlation with upper mantle conductors in Australia. Differences in the correlation pattern between these deposit types likely relate to differences in the chemistry, redox state and location of source mineralizing fluids and magmas, and indicate signatures of mineral system processes can be preserved in the crust and mantle lithosphere for hundreds of millions of years. Appeared in Scientific Reports volume 12, Article number: 8190 (2022), 17 May 2022

<div>The Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) is a collaborative national survey between federal government, state/territory governments and research organisations. The project aims to acquire long-period magnetotelluric (MT) data at half-degree spacing (~55&nbsp;km) across the Australian continent. AusLAMP started in 2013 and has completed about 1500 stations (~50% of total planned stations) to date. Over the last decade, regional-scale AusLAMP resistivity/conductivity models have been produced following data acquisition campaigns, but there is a strong demand for a single model. We produced a resistivity model from 1260 AusLAMP stations incorporating 85% of data acquired to date. The new AusLAMP resistivity model shows significant variations of resistivity at varying depths from a few kilometres to a couple of hundred kilometres in the crust and upper mantle. The model resolves the first-order resistivity structure of the Australian lithosphere across most parts of central and eastern Australia, including Tasmania. The resolved resistivity structures allow seamless interpretation across states and regions, broadly conform with identified major geological domains and crustal boundaries, and reveal significant variations within geological provinces, orogens and cratons. There are also strong spatial associations between crustal/mantle conductors and copper and gold deposits and carbonatites, which provide further evidence that major lithospheric conductors control the distributions of a range of mineral systems. This evidence aligns well with the conceptual model of mineral systems, that convecting mantle fluid and metal-rich magma can migrate into the crust through weak zones to form some ore deposits in the lithosphere. This new AusLAMP model demonstrates that long-period MT data are an important first-order reconnaissance dataset to resolve large-scale lithospheric architecture and provides a powerful tool with a bottom-up approach to highlight potential exploration areas, particularly in covered and under-explored regions. Presented at the 2024 Australian Society of Exploration Geophysicists (ASEG) Discover Symposium

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.

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.

The magnetotelluric (MT) method is increasingly being applied to map tectonic architecture and mineral systems. Under the Exploring for the Future (EFTF) program, Geoscience Australia has invested significantly in the collection of new MT data. The science outputs from these data are underpinned by an open-source data analysis and visualisation software package called MTPy. MTPy started at the University of Adelaide as a means to share academic code among the MT community. Under EFTF, we have applied software engineering best practices to the code base, including adding automated documentation and unit testing, code refactoring, workshop tutorial materials and detailed installation instructions. New functionality has been developed, targeted to support EFTF-related products, and includes data analysis and visualisation. Significant development has focused on modules to work with 3D MT inversions, including capability to export to commonly used software such as Gocad and ArcGIS. This export capability has been particularly important in supporting integration of resistivity models with other EFTF datasets. The increased functionality, and improvements to code quality and usability, have directly supported the EFTF program and assisted with uptake of MTPy among the international MT community. <b>Citation:</b> Kirkby, A.L., Zhang, F., Peacock, J., Hassan, R. and Duan, J., 2020. Development of the open-source MTPy package for magnetotelluric data analysis and visualisation. 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.

It is increasingly recognised that, to maintain a sustainable pipeline of mineral resources in Australia, future discoveries will need to be made in areas obscured by more recent cover sequences. A major challenge to mineral exploration in covered frontiers is identifying new prospective fairways, and understanding and mapping important metallogenic processes at a range of scales to enable more effective targeting of exploration. Here, we present evidence for a completely buried corridor of interpreted high prospectivity—the East Tennant region—based on synthesis and integration of a diverse range of geoscientific datasets. Key indicators of the region’s potential include lithospheric-scale architecture, elevated electrical conductivity in the crust and mantle, and modelled and demonstrated hydrothermal alteration in the near surface. Multiscale geophysical surveys show evidence for crustal-scale fluid flow along major structures, connecting the mantle with the surface. Although few geological constraints exist in this region, examination of legacy drillcore and geochronology results demonstrates a similar history to rocks known to host mineralisation across the North Australian Craton. These results provide tantalising indications that the under-explored East Tennant region has significant potential to host major mineral systems. <b>Citation: </b>Schofield, A., Clark, A., Doublier, M.P., Murr, J., Skirrow, R., Goodwin, J., Cross, A. J., Pitt, L., Duan, J., Jiang, W., Wynne, P., O’Rourke, A., Czarnota, K., and I. C. Roach., 2020. Data integration for greenfields exploration: an example from the East Tennant region, Northern Territory. 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.

Lithospheric structure and composition have direct relevance for our understanding of mineral prospectivity. Aspects of the lithosphere can be imaged using geophysical inversion or analysed from exhumed samples at the surface of the Earth, but it is a challenge to ensure consistency between competing models and datasets. The LitMod platform provides a probabilistic inversion framework that uses geology as the fabric to unify multiple geophysical techniques and incorporates a priori geochemical information. Here, we present results from the first application of LitMod to the Australian continent. We demonstrate the ability to map important geophysical surfaces, and to differentiate between compositional (e.g. metasomatism) and thermal anomalies. We validate the posterior predictions from our inversion against independent studies, and this highlights the robustness of our results. Finally, we discuss recent technological advances in the implementation of LitMod3D_4INV, and how the model can be used to bring together multiple projects within the Exploring for the Future program to image the lithospheric mantle. The implications of this work extend beyond mineral prospectivity, and will ultimately inform our understanding of energy systems, groundwater and seismic hazard. <b>Citation:</b> Haynes, M.W., Fomin, I., Afonso, J.C., Gorbatov, A., Czarnota, K. and Salajegheh, F., 2020. Developing thermochemical models of Australia’s lithosphere. 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.

Estimating the relative contributions of bedrock geology, mineralisation and anthropogenic contamination to the chemistry of samples collected at the Earth’s surface is critical in research and application fields as diverse as environmental impact studies and regional mineral exploration programs. The element lead (Pb) is a particularly useful tracer in this context, representing a toxin of environmental concern and associated with many other anthropogenic contaminants (e.g. mine wastes, waters, paints, aerosols), as well as with mineralisation. Although Pb concentration data are frequently collected in geochemical studies, isotopic analysis offers an important advantage, allowing discrimination between different sources of Pb. The Pb isotopic composition of regolith is likely to reflect contributions from underlying rock (including Pb-rich mineralisation), wind-blown dust and possibly anthropogenic sources (industry, transport, agriculture, residential, waste handling). Regolith samples collected at different depths may show distinct compositions; bedrock isotopic signatures are expected to dominate in deeper soils, whilst airborne dust and anthropogenic signatures are more important at the surface. Pb isotope ratios in the continental crust show large variations, which will be transferred to the regolith, providing a potentially unique bedrock signal that is easily measured. This research program examines if soil Pb isotope mapping can identify the underlying geology and metallogenic provinces, if different sampling and analytical approaches produce very different results, and how anthropogenic signals vary across the continent. Here, we present our results for the Northern Territory, where single regolith samples from many (not all) catchments define apparently consistent isotopic domains that can be interpreted in relation to the underlying geology (crystalline basement, basins) and mineral deposits. <b>Citation:</b> Desem, C.U., Maas, R., Woodhead, J., Carr, G. and de Caritat P., 2020. Towards a Pb isotope regolith map of the Australian continent: a Northern Territory perspective. 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.

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 mineral potential toolkit (aka minpot-toolkit) provides tools to facilitate mineral potential analysis, from spatial associations to feature engineering and fully integrated mineral potential mapping.</div>