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ABSTRACT: Basin inversion associated with continental breakup: examples from the Perth Basin, Western Australia

Song, Tingguang, Mike Middleton, and Peter A. Cawood , Curtin University, Perth, WA, Australia

Perth basin is a northerly striking elongate tectonic province covering both onshore and offshore areas of the southern part of the western Australian continental margin. The basin is controlled by normal faults initiated by the Early Permian rifting and reactivated subsequently. Late Jurassic-Early Cretaceous breakup exerted a NW-SE extension which is oblique to the pre-existing, northerly orientated normal faults. Consequently dextral strike-slip occurred along major pre-existing faults. This resulted in en echelon folds in the Dandaragan Trough in the downthrown side of the Darling Fault system which is the east boundary of the basin. Compressive deformation may also occur at constraining bends either at which the major faults deflect or where are defined by pre-existing linked fault families. The inversion structures have been proved to be one of the major traps in the basin. The breakup also resulted in basin-wide uplift and erosion. The onshore part of the basin mainly remains uplifted since the breakup, whereas the offshore accepted post-breakup deposits of up to 2000 m thick of the Cretaceous-Tertiary in age. The erosion of pre-breakup sequences may be up to 3600 m in the offshore while the erosion is normally less than 2500 m in the onshore.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia