Negligible convergence and lithospheric tearing along the Caribbean–South American plate boundary at 64°W

Abstract

Prior studies of the Caribbean–South American plate boundary have suffered from poor constraint on the structure of the crust and uppermost mantle. We use a recent wide‐angle velocity model from the Broadband Ocean‐Land Investigation of Venezuela and the Antilles arc Region project to constrain new seismic reflection data and previously published line drawing interpretations of the Caribbean–South American plate boundary at 64°W. Though commonly characterized as obliquely convergent, we determine that convergence is negligible in our study area. Previous estimates of Miocene to present north‐south shortening onshore eastern Venezuela have commonly been 115 km or higher, but we constrain shortening to ∼35 km onshore, with an additional ∼30 km offshore. With such minor convergence, we conclude that uplift and basin subsidence in eastern Venezuela does not derive from typical collisional orogeny. Instead, the largely vertical tectonics likely result from mantle dynamics associated with an eastward propagating, near‐vertical tear in the lithosphere along the former passive margin.