--> Abstract: The Structural Foundations of a Major Hydrocarbon Province: the Northern Carnarvon Basin, Australia, by H. M. Stagg and J. B. Colwell; #90987 (1993).

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STAGG, HOWARD M. J., and JAMES B. COLWELL, Australian Geological Survey Organisation, Canberra, ACT

ABSTRACT: The Structural Foundations of a Major Hydrocarbon Province: the Northern Carnarvon Basin, Australia

As part of a network of deep crustal seismic data along Australia's North West Shelf, the Australian Geological Survey Organization has acquired a regional grid of 4500 km (50 km average line spacing) of 16-second record length data throughout the highly-prospective and producing northern Carnarvon Basin (Barrow, Dampier, and Beagle Sub-basins), and the adjacent Exmouth Plateau. This work aims to determine the broad regional structural framework, to decipher the deep structure, to study the effect that reactivation of this structure has on the development of hydrocarbon fields and plays, and to provide modern regional seismic correlations.

The new data set provides extensive information down to 10-11 sec two-way time (15-20 km), particularly beneath the Rankin Platform and Exmouth Plateau, and permits interpretation of the foundations of some of the major hydrocarbon-bearing structures.

The initial interpretation indicates several important points, including:

1. Basin-forming faults in the Barrow and Dampier Sub-basins appear to dip landwards in the Dampier Sub-basin and oceanwards in the Barrow Sub-basin. In combination with the interpretation of other data, this points to a major crustal dislocation extending northwest from the junction of the two sub-basins, across the Exmouth Plateau, to the continent-ocean boundary.

2. Multiple phases of wrenching and strike-slip motion are at least as important as extension in the formation of the region.

3. While Late Triassic to Jurassic faulting, which commonly reactivated pre-existing basin-forming faults, has produced many of the major hydrocarbon-bearing structures, this relatively recent faulting was not the primary event in the formation of the region.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.