| The SE Caribbean Margin Continental Dynamics Project is a multi-disciplinary investigation of the large scale structure and tectonic framework of the northern boundary of South America. To study the deeper mantle and lithospheric structure, we deployed and maintained an 83 station, broadband array in Venezuela with instruments spanning from the craton south of the Orinoco to the oceanic crust of the Caribbean plate. The first contribution of this work is documentation of the deployment and maintenance of the array. I applied body wave tomography to the data collected during the 18 month deployment. The body wave tomography results produce new constraints on the nature of the Caribbean-South American plate boundary, and provide a new tectonic interpretation of the plate relationships at depth. The tomography results indicate the subducting Atlantic plate descends into the mantle at a relatively low angle parallel to the strike-slip plate boundary in northern Venezuela. This contrasts with previous tomography models for this region that suggest the plate steepens to near vertical dip at its southern edge. I argue the previous results are likely a misinterpretation of artifacts from poorer coverage than what was available for this study. The main arguments for this claim are based on the geometry from a three-dimension plate model constructed for the entire Caribbean. Steepening of the plate implied by previous results requires a sharp reversal in the curvature of the subducting slab that is difficult to reconcile with the constraints imposed by active volcanoes in the Antilles Arc. Finally, a related three-dimensional model was developed for the complex southwestern corner of the Caribbean plate. While this area in Western Venezuela is not well resolved by our data, we can offer some constraints on the structure and explain deep earthquakes under Maracaibo. |
