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ABSTRACT: Neogene tectonic influences on petroleum systems in the Browse Basin and Timor Sea, North West Shelf, Australia

Keep, Myra1 and Ian Longley2
(1) University of Western Australia, Perth, Australia 
(2) Woodside Energy Ltd, Perth

The Browse Basin and Timor Sea exhibit a complex array of Neogene structural styles resulting from the collision of the Australian plate with the southern margin of the Eurasian plate in the last 25 Ma. Plate-scale and far field controls, including plate flexure, left-lateral strike-slip and the location of basement fragments, dominate local reactivation patterns, and styles of Neogene reactivation vary significantly with the transition between these controlling elements.

In the Timor Sea reactivated faults, which cluster around the margins of structural highs (e.g. Ashmore and Sahul platforms and Laminaria High), exhibit overall net normal displacement, although this commonly masks a complex structural history. Fault styles change from flexure- to left-lateral wrench-dominated from northeast to southwest (Sunrise/Troubadour to Kelp). In the area outboard of the Ashmore Platform these controls are further complicated by a change in margin orientation, making the area a locus of complex deformation.

To the southwest, in the Barcoo Sub-basin, right lateral wrench deformation has created large transpressional anticlines and continues to offset the seafloor. The change from left- to right-lateral wrench deformation occurs between the Browse Basin and Timor Sea.

These varying Neogene tectonic influences have significant effects on petroleum systems in the Browse Basin and Timor Sea. The timing and nature of reactivation vary between sub-basins, strongly influencing the petroleum prospectivity. Trap failure in the Barcoo Sub-basin may be attributed to Neogene reactivation, whereas petroleum systems in the areas of the Cartier Trough and the Sunrise/Troubador wells have benefited positively.

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