Inelastic yielding and forebulge shape across a modern foreland basin: North West Shelf of Australia, Timor Sea

Abstract

The Timor Trough is a modern `underfilled' foreland and basin created by partial subduction of the outer north west continental shelf of Australia beneath Timor Island in the Outer Banda Arc of eastern Indonesia during the Cenozoic. A change of the effective elastic thickness (EET) of the continental foreland lithosphere from approximately 80±20 km to approximately 25 km over a distance of approximately 300 km explains (1) the high curvature (approximately 10-7 m-1) on the outer Trough wall, (2) the low shelf forebulge (approximately 200 m) as measured along a reference base Pliocene unconformity, and (3) observed gravity. An inelastically yielding quartzite-quartz-diorite-dunite continental rheology can explain the EET gradient. New, shallow crustal (<8 km), seismic reflection images indicate that Jurassic basement normal faults are reactivated during bending of the foreland.