Abstract

The Trinidad region of the southeastern Caribbean is a tectonically complex subduction-to-strike-slip plate boundary transition where distinct changes in the style, size, and orientation of sedimentary basins and uplifted structures occur over short distances measured in kilometers to tens of kilometers. We interpret approximately 10,000 km (6000 mi) of deep-penetration 2-D seismic reflection and well data to map the distribution and continuity of tectono-stratigraphic sequences and to constrain the timing of structures related to basin formation and deformation. The along-strike, plate boundary transition from subduction to strike-slip is documented in the stratigraphic record by differences in the style and deformation in basins overlying South American basement. At the Lesser Antilles subduction margin, the approximately 300-km (180-mi)-wide Barbados accretionary prism (BAP) is situated greater than 1200 m (3900 ft) below sea level. The BAP is characterized by approximately parallel, forward-breaking thrusts overlain by small, semi-isolated piggyback basins and is associated with mud diapirism. The BAP formed above, approximately 5–7-km (16,400–23,000-ft)-thick subducting Atlantic oceanic crust of Jurassic to Early Cretaceous age. In the oblique-collisional and strike-slip zone onshore Trinidad, there is a less than 100-km (60-mi)-wide zone of middle Miocene folding and thrusting cut by later strike-slip deformation—with maximum elevations of 940 m (3000 ft) above sea level. This complex fold-and-thrust-belt includes elevated, anticlinal ranges with intervening synclinal basinal areas. The northwest–southeast-oriented Galera Tear Fault Zone (GTFZ) is a location of incipient lithospheric tearing that is aligned with the boundary between continental crust of South America—which experienced oblique collision and translation—and orthogonally subducting South American (Atlantic) oceanic crust. The southeast Caribbean margin presents a unique opportunity to observe the phases of deformation, which are responsible for complex and superimposed deformation structures in the rock record along the northern South American margin. These deformational phases have developed progressively as the arcuate, eastward-advancing front of the Caribbean plate interacts with northern South America. This study represents progress in the understanding of sedimentary basins and deformation structures, which form and evolve at the Caribbean–South American plate boundary zone with implications for geologic interpretation and petroleum systems evaluation in older segments of the northern South American, and other hybrid subduction-to-strike-slip plate boundary margins.