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.

ABSTRACT This study presents an integrated, mega-regional, subsurface synthesis of the southeastern Caribbean plate margin that incorporates observations from gravity, seismic refraction, outcrop, and approximately 20,000 line-km of high-resolution 2-D seismic reflection data tied to wells. The primary objective of the study is to better understand the tectonic and basinal transitions from the Lesser Antilles subduction zone (LASZ)—characterized by the subduction of the South American oceanic crust beneath the overriding Caribbean plate and the approximately 300-km (185 mi)-wide, deepwater Barbados accretionary prism (BAP)—to the arcuate, obliquely convergent, and transpressional southeastern Caribbean–South American plate boundary zone—characterized by a complex suite of uplifted provinces, foreland basins, and hybrid sedimentary basins. Early Cretaceous aged allochthonous arc terranes, including the island of Tobago and its offshore component, the Tobago–Barbados Ridge (TBR), were accreted along the deeply buried, lithospheric trace of the LASZ and tectonically transported eastward for hundreds of kilometers along northern South America to their present-day position at the leading eastern edge of the Caribbean plate. Along-strike changes in structures of the BAP are related to progressive phases of deformation that involve thickening of prism strata against the TBR-controlled backstop, frontal accretion that forms the main body of the BAP, horizontal shortening, mud diapirism, rotation and uplift of structures, and backthrusting at the western edge of the prism. The Galera Tear fault zone (GTFZ) formed along the Mesozoic continent–ocean boundary (COB) of the northeastern South American plate. The GTFZ accommodates the differential deformation between provinces of the BAP within the LASZ to the northeast and provinces of the oblique collision and strike-slip zone near Trinidad. Basins affected by subduction-to-strike-slip plate boundary interaction undergo superimposed areas of compressional–transpressional, extensional–transtensional, and strike-slip deformation.