Seismic Characterization of Large-Scale Platform-Margin Collapse Along the Zhujiang Carbonate Platform (Miocene) of the South China Sea, Based on Miocene Outcrop Analogs from Mut Basin, Turkey
Xavier Janson, Gregor P. Eberli, Anthony J. Lomando, Florence Bonnaffé, 2010. "Seismic Characterization of Large-Scale Platform-Margin Collapse Along the Zhujiang Carbonate Platform (Miocene) of the South China Sea, Based on Miocene Outcrop Analogs from Mut Basin, Turkey", Cenozoic Carbonate Systems of Australasia, William A. Morgan, Annette D. George, Paul M. (Mitch) Harris, Julie A. Kupecz, J. F. (Rick) Sarg
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Redeposition of carbonate sediment on all scales produces heterogeneous stratigraphic architecture along platform margin, slopes, toe of slope, and basin. Larger features, such as margin collapse or slumps, are visible on seismic sections, but their internal architecture is commonly beyond seismic resolution. Seismic data across the lower Miocene Zhujiang Platform margin in the subsurface of Pearl River Mouth Basin in the South China Sea show truncation of the margin associated with contorted and rotated reflections at the toe of slope and in the basin. This seismic facies occurs discontinuously along the margin in an area approximately 6 to 8 km wide paralleling the margin and 2 to 3 km wide in the dip direction. These seismic features are compared with similar geometries and bedding patterns observed in an analog Miocene platform margin that crops out in south-central Turkey. There several slump scars truncate barrier-margin deposits and are associated downslope with rotated and folded strata that are still connected to these detachment surfaces. The margin-collapse observed in the outcrop allows interpretation of margin truncation and the contorted reflection package observed in the seismic as a large-scale redeposited feature. The margin of the lower Miocene Zhujiang Platform displays multiple large-scale slumping events distributed along strike. In the outcrop, large-scale margin collapse internal architecture is made up of blocks of cemented margin material several tens of meters to a few of hundred meters wide. Using half-time energy instantaneous seismic attributes reveals that large cemented blocks imaged as small energy anomalies on 2D seismic data might also exist within the margin collapse observed in Zhujiang Platform.