Tectono-stratigraphy of the Dampier Sub-basin, North West Shelf of Australia

Abstract

Abstract The Dampier Sub-basin, an inboard rift system of the Northern Carnarvon Basin in the North West Shelf, Australia, underwent two major phases of continental rifting in the Late Paleozoic and in the Latest Triassic to Late Jurassic. Six tectono-stratigraphic megasequences separated by regional unconformities have been identified: (1) Pre-Late Carboniferous Pre-rift 1; (2) Late Carboniferous to Late Permian Syn-rift 1; (3) Early to Latest Triassic Post-rift 1; (4) Latest Triassic to Early Late Jurassic Syn-rift 2; (5) Late Jurassic to Early Cretaceous Post-rift 2; and (6) Early Cretaceous to Present-day passive margin megasequences. The Late Paleozoic rifting produced a series of planar extensional faults on the eastern flank, some of which were later rotated by the Latest Triassic to Late Jurassic WNW–ESE extension to low-angles (c. 30°). This Mesozoic extension was localized above a NE–SW-trending basement structure, resulting in en échelon inboard rift basins and overlapping boundary fault systems. The study outlines an updated basin tectono-stratigraphic model for the Dampier Sub-basin and provides new insights for structural evolution associated with the development of the North West Shelf passive continental margin of Australia.