ABSTRACT: Tertiary Tectonics and Seismic Stratigraphy of the Vulcan Subbasin (Timor Sea, North West Shelf, Australia): Plate Tectonic Implications
LORENZO, JUAN M., and RICHARD R. HILLIS, Flinders University, Adelaide, South Australia, Australia
The Vulcan subbasin (Timor Sea) on the outer Australian North West Shelf, the Timor Trough, and the Island of Timor in eastern Indonesia constitute the western end of a continent-island arc collision system between the Indo-Australian plate and the Banda Arc. Folding and thrusting driven by collision has controlled the development of the main structural elements of Timor. However, the Vulcan Subbasin, a former Mesozoic passive margin basin, has synchronously experienced renewed extension from the Late Tertiary to the present, in response to collision.
The Vulcan subbasin is a northeast-southwest trending system of en echelon rift basins about 150 km long and 50 km wide, created primarily by Mesozoic rifting of eastern Gondwanaland. Depositional sequence mapping over a 50,000 sq km region has provided a geologic time scale for studying the basin and surrounding area. At least five depositional sequences dating from the Paleocene to the present have been identified using 14,000 km of seismic profiles, and electric logs from 77 wells. Fault displacement history shows that Late Tertiary sequences were affected by strike-slip and normal faulting, synchronous with folding and thrust faulting in Timor. These differences in the tectonic regime north and south of the Timor Trough suggest that Timor has remained mechanically decoupled from t e Australian North West Shelf during plate convergence, and imply that a decollement zone has existed below Timor Island since the Late Tertiary.
AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)