Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
AAPG Annual Convention, Houston, Texas, April 9–12, 2006
Stratigraphic Architecture and Basin Fill Evolution of the Columbus Foreland Basin, Eastern Offshore Trinidad
Eastward migration of the Caribbean plate relative to the South American plate is recorded by a 1100-km-long foreland basin which is oldest in the west (65-55 Ma Maracaibo foreland basin) and youngest in the east (15-0 Ma Columbus foreland basin, CB, eastern offshore Trinidad). We have integrated approximately 775 Km of deep 2D seismic lines, 8,000 km2 of shallow 3D seismic data and published well data from the CB to reveal the active tectonic processes that controlled deposition in the older, now subaerial and inactive foreland basins to the west. The late Tertiary basin fill of the CB was divided into 7 unconformity-bound sequences which thicken northward to oblique-slip faults bounding the submarine Darien Ridge. Unconformities indicate a pulsed deformation of the CB extending over the last 15 Ma rather than a single sharp closure event. The various mechanisms creating accommodation space in the eastern offshore area of Trinidad include: 1) down-to-the-northeast normal faults located near the present-day shelf-slope boundary, were maximum normal fault throws are as much as 2200 m and inferred to be Plio-Pleistocene in age; 2) down-to-the-southeast thrust faults located along the Darien ridge, a major ENE-trending bathymetric ridge through the study area where the total estimated fault throw is as much as 15,000 m (Top Cretaceous) and estimated to be upper Miocene to recent in age; and 3) depositional loading by more than 12,000 m of Plio-Pleistocene clastic sediments on partially remobilized Miocene age shale substrates.