A revised Proterozoic tectono-stratigraphy of the South Nicholson region, Northern Territory, Australia — insights from SHRIMP U-Pb detrital zircon geochronology

New SHRIMP U-Pb detrital zircon geochronology on Mesoproterozoic and Paleoproterozoic siliciclastic rocks from the South Nicholson region, in concert with recently acquired complementary regional geophysical datasets, has enabled comprehensive revision of the regional Proterozoic tectono-stratigraphy. The identification of analogous detrital zircon spectra between units deposited in half-graben hanging walls of major ENE-WSW trending extensional faults, the Benmara, Bauhinia, and Maloney-Mitchiebo faults, offers compelling evidence for regional tectono-stratigraphic correlation. Units sampled from the hanging walls of these faults are characterised by immature proximal lithofacies and host a small yet persistent population of ca 1640–1650 Ma aged zircon and lack Mesoproterozoic detritus, consistent with deposition coincident with extension during the River Extension event at ca 1640 Ma, an event previously identified from the Lawn Hill Platform in western Queensland. This finding suggests the hanging wall sequences are chrono-stratigraphically equivalent to the highly prospective sedimentary rocks of the Isa Superbasin, host to world-class sediment-hosted base metal deposits across western Queensland and north-eastern Northern Territory. Subsequent inversion of the extensional faults, resulted in development of south-verging thrusts, and exhumation of late Paleoproterozoic hanging wall siliciclastic rocks through overlying Mesoproterozoic South Nicholson Group rocks as fault propagated roll-over anticlines. These geochronology data and interpretations necessitate revision of the stratigraphy and the renaming of a number of stratigraphic units in the South Nicholson region. Accordingly, the distribution of the highly prospective late Paleoproterozoic units of the McArthur Basin, Lawn Hill Platform and Mount Isa Province is greatly expanded across the South Nicholson region. These findings imply that the previously underexplored South Nicholson region is a highly prospective greenfield for energy and mineral resources. Citation: C. J. Carson, N. Kositcin, J. R. Anderson & P. A. Henson (2023) A revised Proterozoic tectono-stratigraphy of the South Nicholson region, Northern Territory, Australia—insights from SHRIMP U–Pb detrital zircon geochronology, Australian Journal of Earth Sciences, DOI: 10.1080/08120099.2023.2264355