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Mize, K.L.¹, Wood, Lesli², and Mann, P.^3
1Jackson School of Geosciences, The University of Texas at Austin, Austin, TX 78752, phone: (512)380-0831, klmize@mail.utexas.edu
²Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, University Station, Box X, Austin, TX 78713-8924
³Institute for Geophysics, Jackson School of Geosciences, The University of Texas at Austin, 4412 Spicewood Springs Road, Building 600, Austin, TX 78759

The deep-marine depositional margins of offshore Trinidad are located in the tectonically dynamic Southern Caribbean Plate boundary zone near the mouth of the Orinoco River. Mega-3D seismic data volumes in water depths of 300 to 2,960 m show multiple episodes of channelization along transport pathways controlled by sea-floor volcanic uplifts, tectonic compressional uplifts, and regional slopes. Several identified channel systems transport sediment across a sea floor characterized by active faults, mass transport processes, and active and inactive mud volcanoes to the modern Orinoco submarine fan located at the front of the Barbados accretionary prism. Three main classes of channels can be identified on the sea floor on the basis of their morphologic character. Class A channels (200-800 m wide, 15-65 m deep, 1.3-1.45 sinuosities) are the most evolved systems and are located in the northern part of the study area. Meander cutoffs, sediment wave fields, migrated channels, and developed terraces, crevasses, and splays are identified as components of these sediment transport systems. Class B channels (75-500 m wide, 1-25 m deep, 1.0-1.2 sinuosities) are not as well defined and are located farther south in the study area, more distal from the active plate margin but still within the zone of deformation. Class C channels (200-650 m wide, 15-155 m deep, 1.05-1.1 sinuosities) are located in the northwest corner of the study area, in locations most influenced by tectonic processes. Width, depth, and sinuosity vary, not only by channel class, but also by channel reach. Quantitative seismic geomorphology can be used to combine subaerial geomorphic principles of channel evolution with seismic-derived morphology measurements to predict response to extrinsic influences and post-dict historical controls on channel morphology.