The late Paleoproterozoic Buddycurrawa Volcanics, South Nicholson region

The Buddycurrawa Volcanics (BV, Benmara Group) are a sequence of trachyte lavas and interleaved shallow-marine siliciclastic rocks, exposed in the Benmara region, northwestern Mount Drummond 1:250 000 map sheet, Northern Territory. Previous information, including resource potential, on the BV was limited, and stratigraphic correlation with other regional volcanic units was speculative. Our new geochronology data establish the extrusion age of the BV as late Paleoproterozoic, constrained by a maximum age of ca. 1662 Ma (SHRIMP U-Pb zircon) and a minimum age of ca 1631 Ma (in situ laser Rb-Sr on glauconite within vesicles). The BV are, therefore, temporally equivalent to numerous ash fall tuffs reported throughout regional highly prospective late Paleoproterozoic successions. The BV also host vertical siliceous pipes, representing ‘white smokers’—peripheral low-temperature equivalents of black smokers—suggestive of a regional shallow-marine hydrothermal circulatory system and potential for associated base metal mineral systems. The BV are pervasively potassically altered. Laser Rb-Sr dating on matrix secondary microcline returns ages ca. 1612–1323 Ma, reflecting timing of fluid flow responsible for at least some of the potassic alteration. These are broadly consistent with similar estimates of episodes of regional fluid flow and base metal mineralisation and/or remobilisation in the Mount Isa Province.

Citation: Carson, C.J., Kositcin, N., Farkas, J., Champion, D.C., Whelan, J., Redaa, A., Gilbert. S., Henson, P.A., Maas, R., Williams, B. and Doublier, M.P., 2020. The late Paleoproterozoic Buddycurrawa Volcanics, South Nicholson region. 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.