Sedimentary Dynamics of the Salt-Dominated Continental Slope, Gulf of Mexico: Integration of Observations from the Seafloor, Near-Surface, and Deep Subsurface
Charles D. Winker, James R. Booth, 2000. "Sedimentary Dynamics of the Salt-Dominated Continental Slope, Gulf of Mexico: Integration of Observations from the Seafloor, Near-Surface, and Deep Subsurface", Deep-Water Reservoirs of the World, Paul Weimer
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Intraslope mini-basins in more proximal (updip) settings are characterized by the bypass facies assemblage (BFA), in which sedimentation is dominated by MTCs (including debris flows), channels, and overbank sedimentation. More distal settings are characterized by the ponded facies assemblage (PFA), in which sedimentation is dominated by sand-enriched turbidity currents. Nevertheless, ponding of turbidites can occur in the BFA and bypass can occur in the PFA. As the Mississippi River has shifted during the late Pleistocene and throughout the late Cenozoic, it has repeatedly supplied sufficient sediment to fill intraslope mini-basins and cause bypass to the abyssal plain, even across the broadest parts of the continental slope. In late Pleistocene Mississippi deposystems, discrete phases of ponding (with shelf-margin deltas feeding intraslope fans) and bypass (with canyons feeding abyssal plain fans) can be recognized. In the late Brazos-Trinity deposystem, only the ponding phase developed. In ancestral Mississippi deposystems of the Miocene and Pliocene, bypass to the abyssal plain may have occurred across mini-basins dominated by PFA, without the formation of large canyons.
Within a mini-basin, deposition proximal to a sediment entry point may be dominated by sand-rich fan lobes, by mud-rich MTCs, or by channel and overbank deposits. Sand-rich fan lobes, and thus the best reservoirs, should be more characteristic of the most distal mini-basins within a corridor, while MTCs should be characteristic of the most proximal mini-basins. The distal end of a mini-basin may be dominated by complete ponding of turbidity currents, by partial ponding and partial bypass over a low sill, or by bypass through a channel incised into the sill.