Late Archaean synorogenic basins of the Eastern Goldfields Superterrane, Yilgarn Craton, Western Australia: Part I. Kalgoorlie and Gindalbie Terranes

Siliciclastic supersequences of the Kalgoorlie and Gindalbie Terranes post-date ∼2660 Ma deformation, uplift and erosion associated with the amalgamation of arc-related terranes, but were tectonically buried to greenschist or amphibolite facies during the orogenic shortening that accreted the Eastern Goldfields Superterrane to the Yilgarn Craton. The supersequences are synclinal remnants of late-stage basins that were linear zones of subsidence adjacent to north-trending strike-slip faults. Fluvial facies (Merougil, Navajo, Jones Creek, Scotty Creek and Yandal basins) are dominated by sheet sandstones that represent the deposits of medial braid-plains, but proximal channel-and-bar complexes of cobble and boulder conglomerates are also preserved. Submarine facies (Kurrawang basin) range from boulder to pebble conglomerates but are dominantly Bouma turbidites with rare black shales, and record the filling of a proximal canyon that fed a distal submarine fan. Axial depositional systems are preferentially preserved in all basins, but transverse systems are preserved at the base of some fluvial deposits. The gross vertical succession in all basins is from proximal up to distal.The basins developed during two tectonic stages separated by an intervening period of uplift, tilting and erosion, with the southern Kalgoorlie Terrane recording change from a Stage I fluvial to a Stage II deep-marine basin. Stage II fluvial deposits are preserved in the northern Kalgoorlie Terrane and in the Gindalbie Terrane. Sparse palaeocurrents establish sediment dispersal was to the south or southeast, implying uplift to the north or northwest controlled palaeoslopes. Stacking of lithofacies is aggradational and is consistent with limited lateral migration of facies tracts in fault-confined basins. Similar lithofacies and aggradational styles of facies stacking characterise syncollisional sequences of the Cenozoic Coastal Range Basin of Taiwan, and the present-day syncollisional basins of southeastern Taiwan are good analogues of late-stage basins of the Kalgoorlie and Gindalbie Terranes.