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Sequence Stratigraphy Simulations of Carbonate, Clastics, and Mixed Basin Margins

KENDALL, CHRISTOPHER G. ST. C., PHIL MOORE, BARBARA A. BIRDWELL, LINDA ROUCHE, and ROBERT CANNON, University of South Carolina, Columbia, SC, GAUTAM BISWAS, Vanderbilt University, Nashville, TN, and JAMES BEZDEK, University of West Florida, Pensacola, FL

Clastics, carbonates, and their mixtures have different depositional and post-depositional behavior that produces the different margin characteristics seen in seismic sequences. Carbonates undergo early cementation while maintaining higher angles of repose, while clays and sands accumulate at lower-angle slopes whose inclination is proportional to the grain size and post-depositional cohesive behavior. In higher energy regimes, waves or currents winnow less cohesive finer material that is transported downdip to form slope sediments rimming the basin.

Simulation of mixed carbonate-clastic sediment accumulation, tectonism, and eustasy for settings in the Permian basin of west Texas and New Mexico show that sharp differentiation of clastics from carbonates is a product of higher angles of repose that carbonates maintain and the higher rates of clastic input at lowstands in sea level. In contrast, simulation of mixed grain-size margins like the Exmouth Plateau of Western Australia, the Baltimore Canyon, and the Gulf Coast Tertiary indicate that muds are winnowed preferentially from shelf-margin crests but accumulate on slopes, while sands accumulate on higher energy shelves. When they bypass at lowstands in sea level, they accumulate in the near slope basin but not on the slope. Simulation of pure carbonate systems like that of the Ba amian platform suggests that progradation is greatest in areas of low wave and current energy while backstepping and cliffed margins occur in high energy settings.

The ability to accurately simulate mixed carbonate-clastic slopes is a key to development of exploration and production models of these systems.

 

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)