High-grade gold (Au), copper (Cu) and bismuth (Bi) ores in the Tennant Creek goldfield have been mined from hydrothermal magnetite and/or hematite-rich ironstone bodies. Less well known is a style of Au-Cu-Bi mineralisation hosted by quartz vein systems within shear zones outside ironstones. Sensitive High Resolution Ion Micro Probe (SHRIMP) U-Pb-Th analyses of hydrothermal monazite [(LREE)PO4] associated with this mineralisation style at the Orlando East Au-Cu-Bi deposit and Navigator 6 Au prospect yield ages of 1659 ± 13 Ma and 1659 ± 15 Ma, respectively. These ages are nearly 200 million years younger than the age established from ironstone-hosted ores in the district. This new result widens the exploration ‘search space’ for gold into rock formations previously regarded as too young to host this style of mineralisation.
Citation: Skirrow, R.G., Cross, A.J., Magee, C.W., Lecomte, A., and Mercadier, J., 2020. Identification of a new ca. 1660 Ma Au-Cu-Bi metallogenic event at Tennant Creek. 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.