<div>The footprint of a mineral system is potentially detectable at a range of scales and lithospheric depths, reflecting the size and distribution of its components. Magnetotellurics is one of a few techniques that can provide multiscale datasets to understand mineral systems. The Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) is a collaborative national survey that acquires long-period magnetotelluric data on a half-degree grid spacing (about 55 km) across Australia. This project aims to map the electrical conductivity/resistivity structure in the crust and mantle beneath the Australian continent. We have used AusLAMP as a first-order reconnaissance survey to resolve large-scale lithospheric architecture for mapping areas of mineral potential in Australia. AusLAMP results show a remarkable connection between conductive anomalies and giant mineral deposits in known highly endowed mineral provinces. Similar conductive features are mapped in greenfield areas where mineralisation has not been previously recognised. In these areas we can then undertake higher-resolution infill magnetotelluric surveys to refine the geometry of major structures, and to investigate if deep conductive structures are connected to the near surface by crustal-scale fluid-flow pathways.</div><div> We summarise the results from a 3D resistivity model derived from AusLAMP data in Northern Australia. This model reveals a broad conductivity anomaly in the lower crust and upper mantle that extends beneath an undercover exploration frontier between the producing Tennant Creek region and the prospective Murphy Province. This anomaly potentially represents a fertile source region for mineral systems. A subsequent higher-resolution infill magnetotelluric survey revealed two prominent conductors within the crust whose combined responses produced the lithospheric-scale conductivity anomaly mapped in the AusLAMP model. Integration of the conductivity structure with deep seismic reflection data revealed a favourable crustal architecture linking the lower, fertile source regions with potential depositional sites in the upper crust. Integration with other geophysical and geochronological datasets suggests high prospectivity for major mineral deposits in the vicinity of major faults.</div><div> This study demonstrates that the integration of geophysical data from multiscale surveys is an effective approach to scale reduction during mineral exploration in covered terranes.</div> This Abstract was submitted to and presented at the 6th International Archean Symposium Target 2023, 28 July (https://6ias.org/target2023/)

Under the Federal Governments’ Exploring for the Future (EFTF) program, Geoscience Australia (GA) recently acquired the Barkly and South Nicholson deep-crustal seismic reflection surveys (L212 and L210, respectively) in partnership with the Northern Territory Geological Survey (NTGS) and Geological Survey of Queensland (GSQ). The Barkly survey was completed in late 2019 as a collaboration between GA’s EFTF program and NTGS’s Resourcing the Territory initiative. Acquisition started at the Queensland-Northern Territory border near the town of Camooweal. It is comprised of five lines; 19GA-B1 (434.6 km), 19GA-B2 (45.9 km), 19GA-B3 (66.9 km), 19GA-B4 (225.8 km), and 19GA-B5 (39.4 km) (Southby et al., 2021), and was acquired via vibroseis using a nodal geophone system (Fomin et al., 2020), and links into the South Nicholson survey acquired in 2017. In 2019, the Camooweal deep-crustal seismic reflection survey (GSQ Open Data Portal 95590) was acquired by the GSQ as part of the Queensland Government's Strategic Resources Exploration Program (SREP), and was centred on the northwest Queensland town of Camooweal with the total length of acquisition spread over three lines; 19Q-C1 (65.8 km), 19Q-C2 (173.6 km) and 19Q-C3 (60.9 km). The Camooweal survey was acquired via vibroseis using a nodal geophone system and links to the South Nicholson and Barkly surveys (Edwards, 2020). These seismic surveys have improved our understanding of the basins, basement structures and structural evolution of the region. They tie the underexplored region with the more explored and highly prospective McArthur and Mount Isa Province, in which there are now new areas identified for future exploration. The known, mappable extent of the South Nicholson Basin has been increased significantly and a new, potentially Proterozoic age, depocentre, the Carrara Sub-basin, located in the south east of South Nicholson region, has been discovered (Henson et al., 2018; Carr et al., 2019; Carson et al., 2020; MacFarlane et al., 2020). The Carrara Sub-basin is interpreted to include strata equivalent in age to the Isa Superbasin, South Nicholson Group, and the Georgina Basin (Carr et al., 2020) and current work on the NDI Carrara 1 drill hole will further constrain the stratigraphy and geology of the South Nicholson region; providing well control to the extensive network of new deep-crustal seismic acquired in this highly prospective frontier province. The aim of this study is to show the extent of the Carrara Sub-basin sedimentary packages by mapping the lateral extent of sedimentary sequences using seismic data interpretation. This Abstract was submitted/presented to the 2022 Central Australian Basins Symposium IV (CABS) 29-30 August (https://agentur.eventsair.com/cabsiv/)