Print this pageAnalogue Models for Basement-Involved Extension and Inversion Structures in the Timor Sea, North-West Australia
HIGGINS, RICHARD I., and GOEFF W. O'BRIEN
Preliminary interpretations of the basement to the Phanerozoic Browse and Bonaparte basins of the Timor Sea in the north-west of Australia show that it is transected by N, NW and NE Proterozoic fracture systems. Lineament intersections are zones that can localize geological structuring and may focus the transport, precipitation and entrapment of hydrocarbons and mineralized fluids. It is not surprising to learn that many lineaments in this region underlie petroleum and mineral occurrences. As such, these areas are prime targets to investigate the control of basement structures.
Analogue models were designed to test various ideas for basin evolution derived from geophysical interpretation of the Timor Sea area. Models employed silicone putties of contrasting viscosity to represent basement of different composition, and sand to represent basin sediments. Pre-existing basement weaknesses were built into the models to represent large through-going fracture systems. The main objective of the study was to investigate how basement may have influenced basin architecture and fluid movements.
The models indicated that basement to the Timor Sea was a major control on the development of basin structures. The fractures localized steps and flips in basin-bounding faults and the basement composition controlled the style of intra-basinal faulting. Models involving oblique inversion developed strike-slip faults in the sand-cover above reactivated basement features. Such faults may be mis-interpreted as extensional transfer faults. Useful information about timing relationships between structures and possible fluid movements can be gained from such observations.