The structural and depositional history of
the Cooper basin in eastern central Australia has revealed that the basin
is a mildly compressional structural depression controlled by northwest-trending
and northeast-trending pre-Permian basement features. Pronounced pre-Permian
compressions are indicated by northeast-trending major structures, the
Gidgealpa-Merrimelia-Innamincka and Murteree-Nappacoongee trends.
Detailed chronostratigraphic facies analysis,
with closely spaced palynological control, of the Patchawarra Formation
revealed that two pronounced phases of uplift occurred during the Sakmarian.
The major intrabasin highs were rejuvenated during these tectonic events,
as documented by crestal unconformities (middle and upper Patchawarra unconformities).
Evidence of each event is dominantly tectonic in character, with similar
depositional patterns over these highs related to each event. These events
are also recognizable in midflank areas and basin margins with contemporaneous
deposition in deeper parts of the basin.
Results from this research show potential
for future hydrocarbon discoveries within structural, stratigraphic, and
structural/stratigraphic traps in the Cooper basin. Various trap styles
are closely associated with faults, unconformities, and lateral facies
changes. Lowside fault closures, onlap plays, and unconformity traps are
expected to be well
1997. The American Association of Petroleum Geologists. All rights reserved.
received February 22, 1995; revised manuscript received August 6, 1996;
final acceptance November 12, 1996.
Survey of Western Australia, 100 Plain Street, East Perth, WA, Australia
6004 (E-mail: [email protected]).
Centre for Petroleum Geology and Geophysics (NCPGG), University of Adelaide,
Thebarton Campus, University of Adelaide, SA 5005, Australia.
Ltd., 101 Grenfell Street, Adelaide, SA 7000, Australia.
authors wish to thank the Cooper Basin Consortium Group of Companies for
permission to publish this paper. The drafting staffs at Santos Ltd. and
Geological Survey of Western Australia (GSWA) are sincerely thanked for
their efforts in preparing figures.
This paper is
dedicated to the memory of Bill Stuart.