Cyclic development of sedimentary basins at convergent plate margins — 1. Structural and tectono-thermal evolution of some gondwana basins of eastern Australia

Abstract

The Devono-Carboniferous Drummond Basin of eastern Australia formed by extensional tectonics, most probably in a back-arc setting, as an oceanic plate subducted westward under Gondwana's continental margin. Within this basin a syn-rift sequence and a relatively thick post-rift sequence are recognized, and the latter is separated from the overlying Galilee Basin by a mid-Carboniferous unconformity, which heralds a time of relatively mild compression, uplift and folding. The lower Galilee Basin formed as a foreland, secondary peripheral bulge, or mixed-style basin during the Late Carboniferous to Early Permian time interval. A mid-Permian unconformity separates it from the extensive Late Permian to Mid-Triassic upper Galilee Basin, here suggested to be a platform basin. Nest, the main, Mid- to Late Triassic compressional event led to reverse movement along previously normal faults, folding, uplift and erosion of up to 2 km of section from the Galilee and Bowen basins. During Jurassic and Cretaceous times, the Eromanga/Surat/Carpentaria Basin, a platform basin originally >1.7 million km 2 in extent, developed cratonward of the zone of continuing subduction. Subsequently, the culminating extensional event took place further east, where Lord Howe Rise rifted apart from the continental landmass and drifted eastward as oceanic seafloor spread in the Tasman Basin, and widespread uplift and erosion occurred over the eastern Australian coastal area. New data, re-interpretation of existing data and extensive literature support the interpretation of the Phanerozoic tectonic evolution of eastern Australia in a context of convergent plate margins. Within this context, overall eastward migration through time of the subduction zone and associated morphotectonic entities (e.g. the Warburton, Adavale, Drummond, Bowen and Tasman extensional basins) and vertical stacking of unconformity-bound extensional, foreland and platform basins (e.g. the Drummond, Galilee and Eromanga basins) occurred.