2008 Joint Meeting of The Geological Society of America, Soil Science Society of America, American Society of Agronomy, Crop Science Society of America, Gulf Coast Association of Geological Societies with the Gulf Coast Section of SEPM

Paper No. 12
Presentation Time: 10:45 AM

Interaction Between Submarine Channels and Mass-Transport Deposits In An Outer Thrust and Fold Belt of the Western Deepwater Niger Delta

LEE, Eddy, TRIPSANAS, Efthymios, SHIPP, R. Craig and GIBSON, Larry, Shell International Exploration & Production Inc, 200 N. Dairy Ashford, Houston, TX 77079, eddy.lee@shell.com

The objectives of this study are to use 3D volume visualization tools to visually and interactively analyze complex geologic elements in multiple seismic data volumes and to enhance the ability for seismic data interpretation. The study area is located in the western deepwater Niger Delta, characterized by a series of imbricated seaward thrusts and folds formed by the down-dip movement of strata as a result of sedimentary loading and extension at the shelf margin. Deepwater channels and mass-transport deposits were identified using 3D seismic volume visualization, which allows fast volume scanning and extraction of seismic attributes, and multi-volume or attribute rending for use in geologic interpretation. Miocene to Holocene sedimentation is expressed by alternating periods of channels and mass-transport deposits. The channels exhibit higher amplitude reflections and have linear to meandering paths that were easily mapped using seismic attribute extractions. The channel pathways were controlled by the seafloor morphology, associated with the underlying thrust and fold and mass-transport deposits. The largest channel was confined by two large-scale mass-transport deposits. These mass-transport deposits appear to have been diverted by an anticlinal fold in the study area, resulting in the development of a paleo low that captured the channel system. The most recent channel system developed after a period of significant mass-transport deposition that covered almost the entire study area and caused an abrupt change in the channel position (approximately perpendicular to older channels). The recent channel avulsion just northwest of the study area may also contribute to this significant change in channel orientation.