--> ABSTRACT: Reactivation of Mesozoic and Palaeozoic Faults in the Otway Basin, Australia: New Evidence from Thermal and Structural Modelling, by G. T. Cooper and K. C. Hill; #91021 (2010)

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Reactivation of Mesozoic and Palaeozoic Faults in the Otway Basin, Australia: New Evidence from Thermal and Structural Modelling

COOPER, GARETH T., and KEVIN C. HILL

New evidence from computerised cross-section balancing, reflection seismic data, apatite fission track and vitrinite reflectance data illustrate a complex history of multiple burial and uplift events in the Mesozoic Otway Basin of SE Australia. Many of these events have involved the reactivation of Palaeozoic and Mesozoic faults.

Serial cross-section balancing of onshore mapping and offshore seismic data in the eastern Otway Basin shows that extension during Late Jurassic-Early Cretaceous rifling (beta = 1.26) occurred along steeply dipping, planar faults. These faults define a regional basin depocentre (approx. 10 km deep) in the NE-trending Otway Ranges. This region also has structural affinities with analogue models of rift zones where extension is oblique to a pre-existing weakness. This may suggest that the extensional geometry of the eastern Otway Basin has been influenced by a Palaeozoic basement fabric.

Apatite fission track and vitrinite data show that Early Cretaceous extensional faults were inverted during the mid-Cretaceous resulting in widespread uplift and denudation (up to 3.5 km) along the northern margin of the basin. This event is largely defined by thermal data and had a profound influence on the hydrocarbon potential of the basin. A later period of compression in the Mio-Pliocene resulting in the formation of kilometre-scale inversion anticlines. 

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.