Fault zone deformational constraints on Paleogene tectonic evolution in southern Puerto Rico

Paleogene deformation in south central Puerto Rico of Cretaceous-Eocene volcaniclastic sediments and volcanic rocks is characterized by west-northwest trending sinistral strike-slip faults, northeast directed thrusts, and fault-related mesoscopic folds. A west-northwest trending belt of predominantly Eocene age sediments is flanked by Upper Cretaceous rocks; a 8–15 km wide fault zone is spatially coincident with this lithologic belt. Structural data and deformational style indicate that the area is a sinistrally transpressive, slightly north vergent, asymmetric flower structure, of which the upper portion is presently exposed in the belt of predominantly Eocene sediments. Deformational characteristics, in combination with sedimentary and tectonic evidence, constrain evolutionary scenarios of the fault zone (specifically, age and amount of displacement) and the northeastern Caribbean, as discussed herein.