Late Pleistocene Deep-Water Stratigraphy and Depositional Processes, Offshore Trinidad and Tobago
Published:December 01, 2000
Tonya R. Brami, Carlos Pirmez, Curtis Archie, Sookdeo Heeralal, Kelly L. Holman, 2000. "Late Pleistocene Deep-Water Stratigraphy and Depositional Processes, Offshore Trinidad and Tobago", Deep-Water Reservoirs of the World, Paul Weimer
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A 3,000 km2 3D seismic data set on the slope (600-1500 m water depth) offshore Trinidad provides detailed images of the seafloor and shallow subsurface. This data aids in the interpretation of the stratigraphic architecture and depositional/erosional processes in this frontier deep water basin. Three main elements comprise the deposits imaged: channel complexes, mass-transport complexes, and mud volcanoes.
Channel complex range from nearly straight to highly meandering and from single trunk to distributary and braided/anastomosed patterns. Two main channel systems having seafloor expression are interpreted as the most recent conduits for Orinoco River sediment to the braided fan at the toe of the Barbados accretionary prism. Seismic images help define the genetic evolution of these channels.
Sediment pathways are affected by the presence of large mud volcanoes on the present day slope. These mud volcanoes have an average height of 100 m and an average radius of 2km.
Failure of the continental slope is revealed by several thick, widespread mass-transport complexes (MTCs) in the study area. Seismic images illustrate variations in size, transport direction/distance, and emplacement mechanisms for these MTCs. Syndepositional thrusting and linear basal scours as opposed to internally chaotic deposits are interpreted to indicate slump-dominated versus debris-flow dominated MTCs, respectively. The main depositional elements are organized commonly in sequences beginning with basal MTCs, followed by channel complexes capped by a pelagic abandonment interval. This vertical organization is similar to that observed in other intraslope basin and basin-floor fans and is interpreted to reflect base-level control on the stratal architecture.