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Extensional Fault Segmentation and Linkage, Bonaparte Basin, NW Shelf, Australia

Frankowicz, Edyta 1; McClay, Ken 1
1 Fault Dynamics Research Group, Department of Earth Sciences, Royal Holloway, University of London, Egham, United Kingdom.

The Bonaparte Basin, located offshore on the North West Shelf of the Australian passive margin, is an important petroleum province. The basin contains up to 15 km of Phanerozoic, marine and fluvial, siliciclastic and carbonate strata. Important hydrocarbon accumulations within the basin commonly occur in complex structural traps, formed by Mesozoic extensional faults. Neogene reactivation of these faults, along with fault-segmentation and linkage in the Late Cretaceous through Eocene to Miocene strata, have a significant impact on fault seal and trap integrity in the area.

This study presents the results of a detailed structural analysis and fault characterization of the northern Bonaparte Basin using 3D seismic data. Structural interpretation involved advanced seismic attribute analysis, synthetic seismic modelling and 3D visualization.

Three major populations of extensional faults can be identified in the northern Bonaparte Basin. From oldest to youngest, these are: (i) Jurassic N-S-trending syn-sedimentary faults dipping to the east, (ii) Late Cretaceous E-W-striking, S-dipping segmented planar faults and (iii) NE-SW-trending complementary faults, forming characteristic en echelon oversteps. NE-SW-striking faults are interpreted to be the result of Neogene reactivation above weakness zones associated with the underlying E-W-trending structures. Both E-W- and NE-SW-striking fault sets form complex pseudo-conjugate fault systems that are soft linked.

The results presented in this study have implications for understanding fault distribution, geometries and linkages in the northern Bonaparte Basin. The structural model proposed here may be applicable to other basins of the Northwest Shelf of Australia.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009