Analysis Of Structural Deformation Of The Upper Cretaceous And Tertiary Sequences, Timor Sea.
Honours Degree, 1995
University of Adelaide
The analysis of structural deformation of the Upper Cretaceous and Tertiary sequences of the Timor Sea was a project devised to gain an understanding of the fault geometries of the region. The ZOCA 91-03 permit was the main focus of the project, with well ties established mainly in ZOCA 91-04. The approach was to seismically interpret this area, and produce a working geological model to represent the structural deformation of these two blocks in the Timor Sea Zone of Cooperation.
Analysis of the seismic data available shows a number of common fault characteristics. In the Tertiary section, which was the main focus of this project, a general extensional style of faulting is seen. This is unusual since the faulting in the Tertiary was a direct consequence of the Miocene compressional event, as the Australian continental plate subducted beneath the island of Timor. The normal block faulting and fault splays are very characteristic of an extensional regime, not compression as would be expected. However, in the deeper sections there is some evidence of a compressional event causing rotation and reactivation of the older Permian fault sets.
A number of features led to the development of a model that incorporates the flexure of the Australian plate as it subducts beneath the Eurasian Plate. The bending of this crustal slab creates stretching in the upper sequences, resulting in what is seen as an extensional regime, while the compression is only evident below a particular level in the crust. This develops a unique area of 'dynamic balance' between extension, resulting from slab flexure, and the compressional forces from the Miocene compressional event.