The Perth Basin is localised by reactivation of Neoproterozoic shear zones on the western margin of the Archaean Yilgarn Craton in Western Australia. While Ordovician to Silurian sandstones were deposited in the northern Perth Basin, the earliest sediments elsewhere are Middle Carboniferous to Permian in age. A sinistral transtensional regime, during which the main architecture of the basin was established, developed during NE-SW extension between Greater India and Western Australia in the Permo-Triassic. NW-SE shortening with continued NE-SW extension resulted in sinistral transpression in the late-Early to Middle Triassic. Sag-phase sedimentation in the LateTriassic followed this oblique rifting event.
An analogy may be made between the Perth Basin and the Permo-Carboniferous to Jurassic Karoo basins in southern and central Africa and Madagascar. Deposition of the Karoo sequence took place within pull-apart and transtensional basins resulting from sinistral reactivation of basement shear zones. The Indian Gondwana Supergroup, and an equivalent sequence in Antarctica, were deposited within normal fault-bounded graben. The Late Paleozoic to Early Mesozoic formation of the Perth Basin, the Karoo basins of Africa and Madagascar, and the Gondwana basins of India was due to intraplate stress resulting from convergence along the Panthalassa margin of Gondwanaland. Late-Early to Middle Triassic compressional events in all basins mark terminal collision along the Panthalassa margin.
