Geometry, kinematics, paleostress analysis and tectonic model of the extensional fault system deforming the Plio-Pleistocene reefal limestone in southeastern Dominican Republic

Abstract

This paper describes a system of extensional faults oriented NW-SE, NNW-SSE, and ENE-WSW responsible for the tectonic relief of semi-grabens in southeastern Dominican Republic. These faults constitute the natural extension of a previously recognized fault system in western Puerto Rico and the Mona Passage. Paleostress analysis carried out on the faults and fractures in the Pliocene limestone results in a minimum NE-SW stress axis, changing to SSW in the faults that affect the Pleistocene limestone. In contrast, the inversion of focal mechanisms of deep, intermediate, and shallow earthquakes provides a mechanism characteristic of pure thrust, oblique thrust, strike-slip, and normal. Extension in the upper part of the Caribbean crust is accompanied by vertical movements of uplift and subsidence that deform the Plio-Pleistocene coral platform. These movements have been modeled as a broken elastic plate flexed to the trench and incorporated in a more general model of necking in the subducted Atlantic slab. Nevertheless, the flexural mechanism alone can hardly explain the regional extension observed, which is better explained as diffuse rifting, maybe due to the continuity at low rate of the counterclockwise rotation of Puerto Rico.