Abstract. Australian terranes concealed beneath Mesozoic cover record complex Precambrian tectonic histories involving a successive development of several Proterozoic to Paleozoic orogenic systems. This study presents an integrated approach combining K–Ar, 40Ar–39Ar, and Rb–Sr geochronology of Precambrian authigenic illites from the recently discovered Millungera Basin in north-central Australia. Brittle deformation and repeated fault activity are evident from the sampled cores and their microstructures, probably associated with the large-scale faults inferred from interpretations of seismic survey. Rb–Sr isochron, 40Ar–39Ar total gas, and K–Ar ages are largely consistent indicating late Mesoproterozoic and early Proterozoic episodes (~ 1115 ± 26 Ma, ~ 1070 ± 25 Ma, ~ 1040 ± 24 Ma, ~ 1000 ± 23 Ma, and ~ 905 ± 21 Ma) of active tectonics in north-central Australia. K–Ar results show that illites from fault gouges and authigenic matrix illites in undeformed adjacent sandstones precipitated contemporaneously, indicating that advection of tectonically mobilised fluids extended into the undeformed wall rocks above or below the fracture and shear (fault gouge) zones. This study provides insight into the enigmatic time-space distribution of Precambrian tectonic zones in central Australia, which are responsible for the formation of a number of sedimentary basins with significant energy and mineral resources.
Geology and mineral resources of the North-Central Idaho Sagebrush Focal Area: Chapter C in Mineral resources of the Sagebrush Focal Areas of Idaho, Montana, Nevada, Oregon, Utah, and Wyoming