Key issues on the post-Mesozoic Southern Caribbean Plate boundary

Abstract

AbstractA lithospheric-scale, geodynamic model of the Caribbean southern boundary takes into account tectonic and stratigraphic elements previously unconsidered or not well constrained. The Falcón, Bonaire, Blanquilla and Grenada basins are parts of a former single back-arc basin associated with the migrating Mesozoic Caribbean Arc in Late Eocene–Oligocene times. Spreading of the crescent-shaped basin was triggered by declining Caribbean eastward motion in response to increased convergence between the two Americas at around 38–33 Ma. Dextral wrenching along the southern boundary started in western Venezuela at 17–15 Ma and progressed eastward to the El Pilar Fault by 12 Ma. Eastward motion of the Caribbean relative to South America was earlier accommodated by east-progressing, non-partitioned oblique subduction and collision, as illustrated today in eastern Venezuela around the Los Bajos–El Soldado fault system. Extrusion of the Maracaibo and Bonaire blocks towards the NNE started around 5 Ma, thus the dextral Boconó fault is a young feature. Total plate boundary Cenozoic dextral wrenching recorded onshore Venezuela does not exceed 100 km and is more likely to be in the order of 55 km.