Cenozoic stratigraphy of the North Carnarvon Basin: insights for the growth history of carbonate margins of the North West Shelf

Matthew Smith

    Research output: ThesisMaster's Thesis

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    Abstract

    The stratigraphic evolution of the Cenozoic strata was investigated through the interpretation of 2D and 3D seismic surveys, integrated with wireline and biostratigraphic data. Results show that the Cenozoic stratigraphy of the Dampier and Barrow Sub-basins in the North Carnarvon Basin, NW Shelf of Australia, is characterized by two second-order sequences, separated by a late-Miocene to Pliocene sequence boundary. The Dampier and Barrow Sub-basins contain: 1) Base Paleocene to Oligocene siliciclastic-carbonates, 2) Oligocene to early-middle Miocene non-tropical carbonate ramps, 3) early-middle Miocene to late Miocene-Pliocene tropical rimmed platforms, 4) a middle Miocene to Pliocene siliciclastic deposit, 5) late Miocene-Pliocene to Pleistocene non-tropical carbonate ramps and 6) Pleistocene to Recent tropical rimmed platforms.

    The initiation of tropical reef production in the North Carnarvon Basin was likely triggered by local climate, linked to the strengthening of the Leeuwin Current and the northwards migration of the NW Shelf to tropical latitudes. The temporary demise of carbonate reef production was likely a combination of 1) the closure of the Indonesian Throughflow to the North Carnarvon Basin, amplifying regional cooling trends and 2) rapid rise in relative sea-level in response to increasing subsidence rates from Australian and Indonesian Miocene to Recent collisional tectonics. The temporary onset of siliciclastic sedimentation in the Dampier Sub-basin was possibly due to 1) a fall in relative sea-level 2) tectonic uplift and 3) the onset of middle Miocene aridity, decreasing vegetation coverage and increasing the erosion rates of the Pilbara hinterland.

    This study presents new insight on the evolution of carbonate margins and slopes during the Cenozoic in the context of Australia’s tectonic and climatic changes. It also provides a detailed characterization of the Cenozoic overburden in the Dampier and Barrow Sub-basins, which is essential to access for exploration geophysics and future drilling operations. Lastly, this work provides an additional analogue for mixed carbonate-siliciclastic reservoirs in SE Asia.
    Original languageEnglish
    QualificationMasters
    Publication statusUnpublished - 2014

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