SHRIMP U-Pb zircon and monazite geochronology of magmatic, metamorphic and sedimentary rocks sampled from an undercover region informally referred to as ‘East Tennant’, located approximately 200 km east of Tennant Creek, has redefined our knowledge of the geology of this region. These results establish strong temporal links with rocks in the Au-Cu-Bi mineralised Tennant Creek region (Warramunga Province) and the Paleoproterozoic Murphy Province, approximately 270 km to the northeast. Detrital zircon U-Pb analyses of two metasedimentary samples show maximum depositional ages of ca. 1875 Ma and detrital zircon age spectra similar to Warramunga Formation metasedimentary rocks in the Warramunga Province. Additionally, three extrusive rocks and an intermediate intrusive rock have magmatic crystallisation ages of 1858–1849 Ma, synchronous with magmatism in the Warramunga Province associated with the 1860–1845 Ma Tennant Event. Monazite U-Pb analyses of two samples of metapelites from the East Tennant region and Murphy Province record metamorphism at ca. 1845 Ma, which is also synchronous with magmatism associated with the Tennant Event. These new results suggest that the undercover East Tennant region could represent an extension of the Warramunga Province and therefore be prospective for Au-Cu-Bi mineralisation. <b>Citation:</b> Cross, A.J., Clark, A.D., Schofield, A. and Kositcin, N., 2020. New SHRIMP U-Pb zircon and monazite geochronology of the East Tennant region: a possible undercover extension of the Warramunga Province, 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.

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. <b>Citation:</b> 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.

The fundamental geological framework of the concealed Paleoproterozoic East Tennant area of northern Australia is very poorly understood, despite its relatively thin veneer of Phanerozoic cover and its position along strike from significant Au–Cu–Bi mineralisation of the Tennant Creek mining district within the outcropping Warramunga Province. We present 18 new U–Pb dates, obtained via Sensitive High Resolution Ion Micro Probe (SHRIMP), constraining the geological evolution of predominantly Paleoproterozoic metasedimentary and igneous rocks intersected by 10 stratigraphic holes drilled in the East Tennant area. The oldest rocks identified in the East Tennant area are two metasedimentary units with maximum depositional ages of ca. 1970 Ma and ca. 1895 Ma respectively, plus ca. 1870 Ma metagranitic gneiss. These units, which are unknown in the nearby Murphy Province and outcropping Warramunga Province, underlie widespread metasedimentary rocks of the Alroy Formation, which yield maximum depositional ages of 1873–1864 Ma. While parts of this unit appear to be correlative with the ca. 1860 Ma Warramunga Formation of the Warramunga Province, our data suggest that the bulk of the Alroy Formation in the East Tennant area is slightly older, reflecting widespread sedimentation at ca. 1870 Ma. Throughout the East Tennant area, the Alroy Formation was intruded by voluminous 1854–1845 Ma granites, contemporaneous with similar felsic magmatism in the outcropping Warramunga Province (Tennant Creek Supersuite) and Murphy Province (Nicholson Granite Complex). In contrast with the outcropping Warramunga Province, supracrustal rocks equivalent to the 1845–1810 Ma Ooradidgee Group are rare in the East Tennant area. Detrital zircon data from younger sedimentary successions corroborate seismic evidence that at least some of the thick sedimentary sequences intersected along the southern margin of the recently defined Brunette Downs rift corridor are possible age equivalents of the ca. 1670–1600 Ma Isa Superbasin. Our new results strengthen ca. 1870–1860 Ma stratigraphic and ca. 1850 Ma tectono-magmatic affinities between the East Tennant area, the Murphy Province, and the mineralised Warramunga Province around Tennant Creek, with important implications for mineral prospectivity of the East Tennant area. Appeared in Precambrian Research Volume 383, December 2022.