Systematic interpretation and mapping of seismic facies (echo character) recorded on very high-resolution (3.5 & 10 kHz) seismic data reveal the geometry, scales, distributions, and depositional processes of the deep-water deposits within “modern” GOM intraslope basins and on the continental rise seaward of the Sigsbee Escarpment. Piston cores from intraslope basins demonstrate that coring can he used to “ground truth” the seismic interpretations and determine the sedimentary facies associated with various depostional processes. The seismic facies indicate that redistribution of sediment by mass-transport processes is ubiquitous and the wide spectrum of slumps, slides, and debris flows observed range from small, isolated deposits in intraslope basins to large, complex deposits covering hundreds of square kilometers on the upper slope and the continental rise. The seismic facies or reflection character recorded from many intraslope-basin and canyon floors indicate sand-rich deposits. Piston cores confirm that some intraslope basin deposits interpreted as slumps and debris flows from seismic facies are indeed sandy mass-transport facies. Initial comparison of these modem sandy mass-transport facies with sandy facies cored from Pliocene intraslope-basin reservoirs, which have also been interpreted as mass-transport deposits, shows that the two facies are identical. The seismic data also indicate that aggradational channel-levee systems, which are characteristic of deep-sea fans, are rare in modern intraslope basins. In contrast, a few extremely large channel-levee systems are observed to meander seaward from some canyon mouths along the Sigsbee Escarpment (e.g. Bryant and Alaminos canyons), and attest to the large volume of sediments that must have moved through the intraslope basins. In addition, sediment waves indicate areas of sediment redistribution by bottom currents (e.g. contour currents) seaward of the Sigsbee Escarpment.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah