Shining new light on the (previously) dark depths of the East Tennant region

The East Tennant region, located between Tennant Creek and the Northern Territory–Queensland border and centred on the Barkly Roadhouse, is an emerging new frontier both for the geological understanding of the North Australian Craton and for mineral exploration. Geophysical datasets acquired as part of Geoscience Australia’s Exploring for the Future program identified the potential of the East Tennant region as a new mineral exploration fairway (Hackney et al 2020; Schofield et al 2020) with prospective Paleoproterozoic rocks completely concealed beneath relatively thin cover (typically less than 200 m; Bonnardot et al 2020; Czarnota et al 2020). Prior to the East Tennant Project’s program of precompetitive geoscience work, which commenced in 2016, only a few mineral exploration boreholes had been drilled to intersect Paleoproterozoic basement and, as a result, the basement geology of the region has remained poorly understood. Although geophysical data provide tantalising insights into the potential of the East Tennant region to host mineral resources, the task of enabling and facilitating future mineral exploration requires new data to resolve the regional stratigraphy and geological event history. In order to test geophysical interpretations and obtain samples to undertake detailed analysis, a ten-hole stratigraphic drilling program was undertaken in the East Tennant region in late 2020 as part of the MinEx CRC’s National Drilling Initiative (NDI; Schofield et al 2021). T his stratigraphic drilling intersected variably deformed and metamorphosed sedimentary and igneous rocks with lithological characteristics similar to those in the Tennant Creek area (Clark et al 2021a) and confirmed that, overall, these basement rocks occur at relatively shallow cover depths. In places, the Paleoproterozoic basement rocks have been altered and mineralised (Clark et al 2021a). Analyses of drill core samples from the East Tennant NDI campaign included whole rock geochemistry, geochronology, and petrophysical characterisation. The results have revolutionised our understanding of the East Tennant region by establishing its geological framework and mineral potential, as well as its tectonostratigraphic context within the North Australian Craton. Presented at the 2022 Annual Geoscience Exploration Seminar (AGES)