Association between Slope Channel Architecture and Shelf Sediment Supplies: A Quantitative Study of the Tectonically Active Columbus Basin, Trinidad

Ramlal, Kristie A.; Wood, Lesli J.

The Pliocene-Pleistocene section of the Columbus Basin in the deepwater slope off eastern Trinidad provides an opportunity to study channel morphology and evolution, as well as any association between deepwater deposits and the nature of the feeder systems updip on the shelf and shelf margin. Approximately 6500 km2 of merged 3-D seismic data allow interpretation of several mappable surfaces in the south part of the basin across a 4000-ms interval of data and enable imaging of channels in deeper sections below the seafloor. Observations of seismic cross sections reveal several channel incisions between the mapped surfaces, along with extrusive mud volcanoes, mass transport complexes, anticlinal features, and extensional faults. Attribute extractions across proportional slices between surfaces are used to assess temporal and spatial changes in channel morphology and behaviour through quantitative measurements. Channel systems occur as leveed and unleveed systems, exhibiting both incisive and constructional behaviour, while slope changes within the basin affect channel geometry and surrounding architecture. Well data allow calculation of net:gross ratios that are assessed relative to any morphologic changes. Other goals include relating variations in channel morphology and distribution to (1) structural features, (2) proximity to the Orinoco delta source, and (3) eustatic variations. Results of this study will enable linking of deepwater-channel morphology with sediment type, provide a predictive model for slope aggradation versus bypass of sediments to ultra-deep locations, and result in a temporal history of Tertiary sediment movement from shelf to ultra-deep repositories.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013