John E. Damuth¹, Hilary Clement Olson²

(1) University of Texas at Arlington, Arlington, TX
(2) The University of Texas at Austin, Austin, TX

ABSTRACT: Evaluation of Latest Quaternary Depositional Processes and Geohazards in Texas-Louisiana Intraslope Basins Based on High-Resolution Seismic Facies and Shallow Piston Cores

Systematic mapping of 3.5 kHz seismic facies (echo character) reveals the geometry, scales, distributions, and depositional processes of Late Quaternary deep-water deposits within the GOM intraslope basin province and seaward of the Sigsbee Escarpment. Piston cores were used to "ground truth" the seismic facies interpretations and determine the sedimentary facies associated with various depostional processes. The seismic facies indicate that mass-transport processes are regionally ubiquitous in intraslope basins and on the upper continental slope. Piston cores confirm the seismic interpretations of mass-transport deposits and show a wide spectrum of slumps, slides, and debris flows in intraslope-basin deposits. These include sandy debris flows, which provide criteria for correctly identifying sandy mass-transport vs turbidite reservoirs in deeper, potentially productive intraslope-basin deposits. The seismic and core data also indicate that aggradational channel-levee systems, characteristic of small deep-sea fans, are rare, but do feed some modern intraslope basins. In addition, some large turbidite pathways through the intraslope-basin province (e.g. Bryant Canyon pathway) feed extremely large channel-levee systems and fans that build seaward from the Sigsbee Escarpment, and attest to the large volume of sediments that have flowed downslope via the intraslope basins through complex fill and spill histories. Extensive fields of migrating sediment waves south and east of the Sigsbee Escarpment indicate that strong, regional bottom-currents have redistributed sediments throughout large areas of the Sigsbee Abyssal Plain. Our 3.5 kHz seismic facies map and core studies also provide useful regional information for future assessment of geohazards related to platform and pipeline placement.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado