High-Resolution Seismic Stratigraphy of a Late Pleistocene Submarine Fan Ponded by Salt-Withdrawal Mini-Basins on the Gulf of Mexico Continental Slope

摘要

The late Pleistocene Brazos-Trinity Fan, a structurally ponded fan completely exposed and undisturbed on the seafloor, was mapped with a combination of conventional and high-resolution seismic data. This fan occupies three salt-withdrawal mini-basins (Ⅰ, Ⅱ, Ⅳ) and a graben (Ⅲ), each filled with an onlapping package consisting of alternating bedded and non-bedded units evident on high-resolution data. Basins Ⅰ-Ⅲ are filled to their topographic spill points; the onlap-fill succession of each is incised by a channel system which bypassed sediment to the next basin(s) downdip. Seismic continuity generally increases distally in the system and within individual basins, believed to reflect the increasing prevalence of turbidity currents over high-density sediment gravity flows.