Integrated tectonic evolution of the Aves remnant arc, Lesser Antilles active volcanic arc, Tobago forearc, and Barbados accretionary prism of the southeastern Caribbean

Abstract

The Trinidad region 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 from kilometers to tens of kilometers. We use ~10,000 km of deep-penetration 2-D seismic reflection and well data to interpret the distribution and continuity of tectono-stratigraphic sequences and to constrain the timing of structures related to basin formation or inversion. The along-strike 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 subduction margin an ~300-km-wide accretionary prism situated .1,200 meters BSL is characterized by approximately parallel, forward-breaking thrusts flanked by small, semi-isolated basins. This prism formed above, ~5-km-thick, subducting Atlantic oceanic crust. In the strike-slip zone there is a <100-km-wide area of predominantly strike-slip with maximum elevations of 940 meters ASL. This deformed area includes provinces which were deformed by shortening and include imbricated and over-thrusted ridges, and an asymmetric foreland basin, overlying ~30-km-thick, thinned continental crust. The NW—SE oriented Galera transfer fault is a reactivated Jurassic fracture zone that accommodates right-lateral motion between the crustal provinces of the strike-slip and subduction zones. We interpret the Tobago-Barbados ridge as a wedge of arc-type crust occupying the area of lithospheric subduction between the front of the Caribbean plate and the subducting, Atlantic plate. The relative positions of the Aves Ridge, Grenada back-arc basin and active, Lesser Antilles arc can be explained by early Cenozoic rollback of the subducted Atlantic slab.

AAPG Datapages/Search and Discovery Article #90330©2018 AAPG Hedberg: Geology of Middle America – the Gulf of Mexico, Yucatan, Caribbean, Grenada and Tobago Basins and Their Margins “Integration of the geology of the area from the southern onshore of North America to the northern onshore of South America”, Siguenza, Guadalajara, Spain, July 2-5, 2018