A Neogene Carbonate Platform, Slope, and Shelf Edifice Shaped by Sea Level and Ocean Currents, Marion Plateau (Northeast Australia)
Alexandra R. Isern, Flavio S. Anselmetti, Peter Blum, 2004. "A Neogene Carbonate Platform, Slope, and Shelf Edifice Shaped by Sea Level and Ocean Currents, Marion Plateau (Northeast Australia)", Seismic Imaging of Carbonate Reservoirs and Systems, Gregor P. Eberli, Jose Luis Masaferro, J. F. “Rick” Sarg
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More than 1700 km of high-resolution seismic data were collected over the Marion Plateau, northeast Australia, to investigate the influence of sea level and oceanography on subtropical carbonate platforms growing on the plateau surface. Seismic data, interpreted in combination with sediments recovered during Ocean Drilling Program Leg 194 and modern oceanographic data, have enabled characterization of the parameters controlling platform growth and development in this region.
Most modern carbonate platforms, such as the Bahamas Platform, have sedimentation patterns that reflect the prevailing wind direction where sediments are forced off the platform on the leeward side, leaving the windward side relatively sediment-starved. This results in platform asymmetry with steep windward and gentler leeward slopes. The seismic data presented here indicate that the carbonate platforms off northeast Australia, although similar in morphology to the Bahamas Platform in many respects, are dominated by oceanographic currents as the primary energy source creating a similar asymmetrical platform geometry where the upcurrent side of the platform is relatively sediment starved and most sedimentisdepositedonthe downcurrent slope. Currents in the study area are dominated by the southward-flowing East Australian Current that generally flows opposite to the prevailing Southeast Trade Winds. This current likely determines not only the morphology, but also the growth potential of the platforms, as well as the volume and final location of sediment transported from the platform top.
Despite the massive, tablelike structures exhibited in the seismic data, Leg 194 drilling demonstrated that the platforms are almost entirely composed of the remains of cool, subtropical organisms, such as red algae, bryozoans, and larger benthic fo-raminifera. Coralline algae were notably absent from most sequences. These calcite-dominated organic remains have a low diagenetic potential, resulting in uncemented and friable slope successions. Nevertheless, the platform tops are well cemented. The fact that the cool subtropical faunal assemblages produce platform geometries that are similar to tropical carbonates suggests that physical parameters, such as current flow and sea level change, may be more important than biofacies in establishing platform architectures.
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Recent advances in seismic acquisition, processing and visualization techniques image carbonate strata with unprecedented resolution. This volume documents the current state of the art in seismic imaging and interpreting of carbonate systems and captures the dynamics of the carbonate system on a large exploration scale and on a small reservoir scale. The book emphasizes the newest approaches in seismic visualization, seismic sedimentology and stratigraphy, seismic attribute analysis and their application for building improved 3-D reservoir models. Among the topics covered are the delineation of the complex histories of carbonate platform sequences from seismic data, the relationships between geometries and forming processes, the imaging of faults for improved mapping of potential fluid migration pathways, and use of seismic attributes for the extraction of rock properties in the sedimentary bodies. The book illustrates the power of integrating seismic and geological data to better predict of the architecture and heterogeneities in carbonate depositional systems. As such the book will be a useful reference for both geologists and geophysicists.