PESA WA Branch September Lunch – Salt Tectonics within the Petrel Sub-basin


PESA WA Branch hosted Chris Elders, Curtin University at their September luncheon where Chris discussed some of the findings of recent research into the salt tectonics within the Petrel Sub-basin and the salt structures that these processes have formed over time.
Chris mentioned a seismic stratigraphic study that showed the relationship between salt structures and the complex multi-phase evolution of the Petrel Sub-basin. Changes in thickness of the surrounding sediments indicate that the salt was deposited as part of the syn-rift sequence, and a significant phase of mini-basin formation across large areas ensued until the end of rifting.
During the lower Palaeozoic a thick section of Carboniferous to Triassic sag sequence developed as some of the early salt structures grew into high-relief diapirs due to early salt withdrawal and subsequent passive growth. In the Middle Jurassic, extensional fault reactivation related to the rifting outboard resulted in accelerated subsidence in the central Petrel Sub-basin, as compressional salt cored folds and diapirs tightened via compression to balance the extension along the basin margin. A final stage of diapir growth was then related to compression from Australia’s collision with SE Asia during the Neogene, supported by the inversion seen along segments of the basin bounding fault system.
The lively discussion at the end of the talk turned to why salt structures are most prolific in the Petrel Sub-basin, whether the salt is of a similar age and origin to other identified salt structures on the Northwest shelf, and questions on how extensive salt deposition may have been.
For those wanting to learn more about salt structures, PESA WA is hosting Kevin Hill from October 22-25 as he presents a short course on structural geology and seismic on Petroleum exploration and the last day will cover the definition, properties, location, and development of salt as well as the different structures produced. Register here to secure a place.
We would like to thank our four sponsors of the PESA WA Branch technical series: Spectrum (Platinum), CGG (Gold), Searcher Seismic (Gold) and DUG (Gold).


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