Regional Offshore Mapping of Structures and Depocenters of Venezuela and Trinidad: Implications for Deepwater Exploration in the Caribbean

Paul Mann and Alejandro Escalona
Jackson School of Geosciences, The University of Texas at Austin, Austin, TX

Regional mapping of ~10,000 km of GULFREX 2D seismic data offshore Venezuela and Trinidad reveal the dimensions, basin type, and filling history of eight, poorly-explored, Tertiary depocenters. These buried and deformed depocenters are significant both for their use as piercing points to reconstruct the amount of Caribbean-South America right-lateral plate motion and because of their hydrocarbon potential. The depocenters are related to three zones of deformation produced by eastwardly-younging oblique arc convergence: 1) a southern zone of south-directed thrust deformation and associated foreland basins (Columbus basin); 2) a central zone of undeformed or weakly deformed basinal rocks deposited in a Paleogene backarc basin behind the eastwardly-moving Caribbean arc (Bonaire-Grenada basins) and a late Paleogene forearc basin in front of it (Tobago basin); locally deformed areas of the Bonaire basin are associated with Miocene transtension of the Dutch Antilles and northeastward motion of the Maracaibo block; and 3) a northern zone of north-directed thrust deformation associated with backthrusting and subduction of the Caribbean plate beneath the central zone (Los Roques basin). The main contributor of Tertiary deepwater sediments to on- and offshore foreland basins of the southern zone is the early Miocene to recent proto-Orinoco fluvial system. The main contributor to offshore basins of the central zone is the Paleogene to Middle Miocene proto-Maracaibo river much of which is preserved in the 5-km-thick Tobago forearc basin. Uplift of the Merida Andes and Cordillera de la Costa in Oligocene through Pliocene time diverted drainage from the proto-Maracaibo river to the proto-Orinoco river.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005