HR: 0800h
AN: H41B-0303    [Abstracts]
TI: Debris Flow Architecture and Processes in Offshore Trinidad: Implications for basin fill in tectonically active margins
AU: * Moscardelli, L
EM: moscardellil@mail.utexas.edu
AF: UT Jackson School of Geosciences, University Station, Austin, TX 78713-8924
AU: Wood, L
EM: lesli.wood@beg.utexas.edu
AF: Bureau of Economic Geology, Jackson School of Geosciences, University Station, Austin, TX 78713-8924 United States
AU: Mann, P
EM: paulm@utig.ig.utexas.edu
AF: Institute for Geophysics, Jackson School of Geosciences, 4412 Spicewood Springs Road, Suite 600, Austin, TX 78759 United States
AB: The eastern continental margin of Trinidad is situated along the tectonically active oblique converging southeastern boundary of the Caribbean and South American plates and proximal to the Orinoco Delta. Factors that have contributed to gravitational instabilities in the shelf edge include high sedimentation accumulation rates, high frequency sea-level fluctuations during the Quaternary, frequent earthquakes and the abundance of methane hydrate. This volatile mix of factors favor the formation of episodic gravity induced deposits that have affected thousands of square kilometers of the deep marine environment. Debris flows are the predominant type of gravity induced deposits in the area. Multiple episodes of debris flow occurrence have been identified using nearly 10,000 square kilometers of three-dimensional seismic data that cover the entire eastern margin. Units can reach up to 250 meters in thickness and occur over 100's of kilometer square areas. Maps that have been generated for the uppermost flow show significant basal scour, up to 33 meters deep generated during passage of the flow. Scours also show divergent patterns in map view indicating changes in the flow conditions. Flow scour erosional shadows around prominent seafloor mud volcanoes preserving evacuated strata on the downslope side of these obstructions. Internal architecture shows high amplitude discontinuous and chaotic seismic facies, and stacked thrust imbricates association with compressional bends in the flow path. The scale and occurrence frequency of these features suggest that they may form a significant threat to submarine installations and possibly generate tsunamigenic waves that can threaten shipping and coastal communities.
DE: 3022 Marine sediments--processes and transport
DE: 3025 Marine seismics (0935)
DE: 3045 Seafloor morphology and bottom photography
DE: 1815 Erosion and sedimentation
DE: 1824 Geomorphology (1625)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting