ABSTRACT: Structural Development and Control on Stratigraphy and Sedimentation in Cooper Basin, Northeastern South Australia and Southwestern Queensland

APAK, S. N., W. J. STUART, and N. M. LEMON, National Centre for Petroleum Geology and Geophysics, University of Adelaide, Adelaide, South Australia

The Cooper basin of Central Australia is a northeast-elongated, Permian-Triassic, mildly compressional, intracratonic basin. The pronounced pre-Permian compressional events are indicated by northeast-trending major structures, the Gidgealpa-Merrimelia-Innamincka and Murteree-Nappacoongee Trends. Determination of the timing and scale of structural movements of the Permian sequence, recognition of unconformities, and reconstruction of paleogeography were the main techniques used to define stratigraphic and sedimentologic patterns and play types within the sequence. Detailed chronostratigraphic facies analysis of the Patchawarra Formation with tight palynological control revealed two phases of uplift as documented by crestal unconformities (middle and upper Patchawarra unconformities). E ch event is dominantly tectonic in character with similar depositional patterns over the highs related to each event. These events are also represented in mid-flank areas and basin margins with contemporaneous deposition in deeper parts of the basin. Structural inversion has been observed over the Big Lake and Moomba fields. Prior to the Sakmarian uplifts, the Moomba field was structurally higher than Big Lake field. This is shown by the deposition of the thick Tirrawarra Formation and the lower Patchawarra Formation in the Big Lake field. After these episodes of uplift, the Moomba field became a depocenter as indicated by thick, later Permian sediments. Late Permian and Late Triassic uplifts results in a further rejuvenation of the main trends with significant erosion of sediments from he highs and basin margin.

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)