Cenozoic Evolution of the Northern Gulf of Mexico Continental Margin
Published:December 01, 2005
William E. Galloway, 2005. "Cenozoic Evolution of the Northern Gulf of Mexico Continental Margin", Petroleum Systems of Divergent Continental Margin Basins, Paul J. Post, Norman C. Rosen, Donald L. Olson, Stephen L. Palmes, Kevin T. Lyons, Geoffrey B. Newton
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Winker (1982; 1984) provided the first summary overview of the depositional evolution of the Gulf of Mexico continental margin, along with a suite of criteria for margin recognition. The subsequent more than 20 years of exploration deep drilling in the Gulf has substantiated both his methodology and synthesis. This paper updates Winker’s map and locates the paleo-continental margin at the termination of 17 principal Cenozoic depositional episodes (deposodes). Northern Gulf of Mexico margins are characterized by a family of attributes, including transition from outer shelf to upper slope faunal assemblages, syndepositional extensional growth structures, rapid thickening along margin-parallel depoaxes, change from relatively continuous, progradational delta and shelf to highly discontinuous, aggradational slope facies successions, local development of erosional submarine canyon heads and slump scars, and increased regional dip.
Cenozoic shelf margin types include: (1) stable progradational margins; (2) unstable progradational margins, typically associated with high-rates of sediment supply by extra-basinal fluvial systems to large shelf-margin deltas and their associated shore-zone systems; (3) retrogradational margins created abruptly by rapid sub-regional salt withdrawal, commonly accompanied by submarine mass wasting and erosion or slowly by long-term compactional subsidence; and (4) perched margins formed by progradation onto foundered continental shelves. Rates of shelf edge offlap vary greatly in both time and space along the northern Gulf of Mexico margin. Highest rates exceed 30 km/Ma and are associated with Oligocene, middle Miocene, and Plio-Pleistocene depocenters.