<div><strong>Output Type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short Abstract: </strong>As part of the Exploring for the Future (EFTF) program, Geoscience Australia acquired new 2D seismic reflection data across the northwestern Northern Territory (NT). Identified as an area of little knowledge during the Birrindudu Basin Inventory activity the Northwest Northern Territory Seismic Survey was acquired between August and September 2023 by Geoscience Australia and co-funded by the Northern Territory Government. The survey crosses the Proterozoic rocks of the Birrindudu Basin that are thought to be age equivalent to those within the McArthur Basin and Mount Isa Province to the east, which contain some of the world’s largest sediment-hosted base metals deposits, including McArthur River and Century and Mt Isa Pb-Zn-Cu mines. Further, additional complimentary studies provide evidence for an effective petroleum system in the Birrindudu Basin, demonstrated by the occurrence of live oil bleeds in the drill hole 99VRNTGSDD1 and good source rocks were identified mostly in the Paleoproterozoic Limbunya Group. However, many data gaps exist and much of the prospectivity for hydrocarbons in the Birrindudu Basin is inferred from the presence of equivalent-aged rocks in the highly prospective Paleo- to Mesoproterozoic McArthur Basin. To address data gaps, this new regional 2D seismic data was acquired and combined with a comprehensive sampling and analytical program on newly collected drill core samples, to assess the basin’s resource potential. The Northwest Northern Territory Seismic Survey has increased the seismic coverage of the Birrindudu Basin by ~900 km, and links to surveys in both the Beetaloo Sub-basin and Tanami. Interpretation of these deep seismic lines in combination with newly acquired data from drill cores and legacy 2D seismic lines will substantially improve the knowledge of mineral and energy systems in the northwestern Northern Territory.</div><div><br></div><div><strong>Citation: </strong>Henson, P., Anderson, J.R., Southby, C., Carson, C., Costelloe, R.D., Jorgensen, D., Grosjean, E. & Carr, L.K., 2024. Northwest Northern Territory Seismic Survey - resource studies and results. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts. Geoscience Australia, Canberra. https://doi.org/10.26186/149332</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>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>

<div>Australian sediment-hosted mineral systems are important sources of base metals and critical minerals that are vital to delivering Australia’s low-carbon economy. In Australia, sediment-hosted resources account for ~82% and ~86% of the total zinc (Zn) and lead (Pb) resources respectively. Given their significance to the Australian economy, four national-scale mineral potential models for sediment-hosted Zn-Pb mineral systems have been developed: clastic-dominated siliciclastic carbonate, clastic-dominated siliciclastic mafic, Mississippi Valley-type and Irish-type. In addition to the potential for Zn-Pb mineralisation, the uncertainty related to data availability has been examined. The mineral potential models were created using a mineral systems-based approach where mappable criteria have been used to assess the prospectivity of each system. Each model has been derived from a large volume of precompetitive geoscience data. The clastic-dominated siliciclastic carbonate mineral potential model predicts 92% of known deposits and occurrences within 15.5% of the area, the clastic-dominated siliciclastic mafic mineral potential model predicts 85% of deposits and occurrences within 27% of the area, and the Mississippi Valley-type mineral potential model predicts 66% of known deposits and occurrences within 31% of the area. Each model successfully predict the location of major sediment-hosted Zn-Pb deposits while highlighting new areas of elevated prospectivity in under-explored regions of Australia, reducing the exploration search space by up to 85% for sediment-hosted Zn-Pb mineral systems.</div>

<div><strong>Output type: </strong>Exploring for the Future Extended Abstract</div><div><br></div><div><strong>Short abstract: </strong>Australian sediment-hosted mineral systems play a crucial role in providing base metals and critical minerals essential for the global low-carbon economy. The Georgina Basin has the key components for forming and preserving a sediment-hosted Zn-Pb mineral system, but historically has been considered ‘cover’ to deeper, more prospective Proterozoic basement rocks. Thus, the basin has remained relatively under-explored, with many questions yet to be resolved on its sediment-hosted Zn-Pb mineral system and prospectivity for Zn-Pb. Utilising new whole-rock and isotope geochemistry of the Georgina Basin from recently drilled holes in the Northern Territory, we demonstrate the sensitivity of local redox boundaries to detect regional mineralisation. Two geochemically enriched zones have been identified and interpreted as redox interfaces which have trapped and concentrated metals from the surrounding basin, a ‘supergene zone’ and a ‘water intercept zone’. The ‘supergene zone’ is a paleo water table horizon, while the ‘water intercept zone’ is an active redox front at the uppermost part of the Cambrian Limestone Aquifer. The enrichment of these redox zones is consistent across multiple drill holes, reaching up to 395 ppm Pb and 1550 ppm Zn. Additionally, the Pb isotopes of high-Pb and sulfidic intervals have a highly radiogenic character (206Pb/204Pb ~22.0–23.0) that is diagnostic of Georgina Basin’s Mississippi Valley-type Zn-Pb mineralisation. Taken together, these results suggest there may be buried mineralisation in this part of the Georgina Basin, as well as highlight the potential of these redox interfaces as a regional reconnaissance target for exploration.</div><div><br></div><div><strong>Citation: </strong>Schroder I.F., Huston D. & de Caritat P., 2024. The geochemistry of redox interfaces for insights into Zn-Pb prospectivity in the Georgina Basin. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://doi.org/10.26186/149116 </div>