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Structural History Of The Officer Basin: 2D Seismic Data Interpretation And Evaluation Of The Structural Geology Of The South Australia/Western Australia Officer Basin

Altmann, Carl M.

Geoscience Honours Degree, 2011

University of Adelaide

Abstract

The Officer Basin covers a total area of 525,000km2 in Central Australia, straddling the South Australian and Western Australian borders. Petroleum exploration in the Officer Basin has been limited considering the vast size of the basin. Within the South Australian section of the basin, less than 7200km of 2D seismic data has been shot and 70 holes drilled, of which 30 are deeper than 500m, and only 12 are petroleum wells. Due the lack of exploration activity, the data set that is available for use in studying the Officer Basin is quite small.

The acquisition of new 2D seismic data by Rodina Oil Corp (2007-2010), within PEL-81 in the South Australian Officer Basin,has allowed for a detailed study on the structure and structural evolution of the South Australian Officer Basin.

From the seismic interpretation of this new South Australian Officer Basin 2D seismic data a few interesting structural features were identified, with a Marinoan aged canyon and a possible reef being the most significant and interesting finds. A Marinoan aged canyon striking NE-SW, intersected in places by Alice Springs Orogenic thrusts deforming the canyon sedimentary fill, was named the Narana canyon. The canyon is expressed by the base Narana formation or the named Narana unconformity. The Narana canyon was interpreted to be of similar age to the Wonoko canyons in the Adelaide Geosyncline. Normal faulting of probable Cambrian age was identified directly beneath the Narana canyon.

A possible reef, equivalent to the Brighton Limestone in the Adelaide Geosyncline, was identified between interpreted Sturtian and Marinoan unconformities. The extent of the reef that survives in the seismic could be restricted to a shallow shelf.

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From the seismic interpretation results, a model for the development of the Narana canyon was proposed. The Narana canyon was likely initiated by oblique strike slip thrusting during the Petermann Orogeny. The subsequent depression was deepened during the Cambrian, with a combination of erosion from a sub-aerial river system and the development of a Negative Flower structure below the canyon from sinistral oblique strike-slip faulting. Finally, Petermann aged thrust faults were reactivated during the Alice Springs Orogeny and caused thrust folding of the Narana canyon fill sedimentary units.              

Australian School of Petroleum
THE UNIVERSITY OF ADELAIDE

SA 5005 AUSTRALIA

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