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The Mesozoic And Tertiary Development Of The Ceduna Depocentre, Great Australian Bight Basin.

Pickavance, David Lindsay

Honours Degree, 1989

University of Adelaide

Abstract

The Ceduna Depocentre contains up to 12 km of sediments, and was the main depositional site in the Great Australian Bight Basin from the late Jurassic to Recent.

Fault characteristics and fault activity were investigated, to relate structural development of the depocentre to tectonic evolution of the southern Australian margin. Fault activity was measured from seismic sections as both the average growth across faults per million years, and the rate of fault termination per million years. Periods of high fault activity, shown by these methods, correspond directly to ages of rifting, breakup and ridge jump tectonic activity. It was concluded that tectonic evolution of the margin was the controlling factor for structural development of the Ceduna Terrace.

Facies associations and sequence stratigraphy were examined to establish the influence of the southern margin evolution on stratigraphic development. Facies maps of the depocentre showed that axial drainage, fan delta, and shelf margin systems tract wedge facies were structurally controlled in the depocentre. Regional tectonic evolution also controlled subsidence rate, and hence influenced the location and environment of facie.

The possibilities for structural and stratigraphic traps were assessed from the above studies, and reservoir and source potential were evaluated from facies maps and systems tract interpretation. Hydrocarbon potential within the depocentre is considered to be good, with most early Cretaceous continental to marine sediments currently in the oil maturity window.

Australian School of Petroleum
THE UNIVERSITY OF ADELAIDE

SA 5005 AUSTRALIA

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