Multistage deformation of linked fault systems in extensional regions: an example from the northern Perth Basin, Western Australia

Linked fault systems identified in the northern portion of the onshore Perth basin comprise north-striking normal faults, the dominant structures in the basin, and hard linkages-east-striking transfer faults. The former are either divided into segments of distinctive character by, or terminate at, the transfer faults. The fault systems were initiated by west-southwest-east-northeast extension in the Early Permian but were reactivated by subsequent rifting with approximately east-west extension in the Jurassic, They were also reactivated by the oblique extension of northwest-southeast orientation associated with Gondwana continental breakup in the Late Jurassic-earliest Cretaceous. In addition to reactivation, older structures of the linked fault families controlled the development of younger fractures and folds. During the oblique extension, the linked fault systems define releasing bends, characterised by a rollover anticline in the hangingwall of the Mountain Bridge Fault, and restraining bends where contractional folds are sites of major commercial hydrocarbon fields in the basin.