Geologic and tectonic history of the eastern section of the Sabana Grande Quadrangle (Puerto Rico)

The mapping of the eastern section of the Sabana Grande Quadrangle provided new data about the geologic and tectonic evolution of the Southwest Igneous Province of the island of Puerto Rico from Lower Cretaceous to Miocene age. The area has been divided into 8 distinct geologic formations (from oldest to youngest) based on lithological comparisons to previous nomenclatures: Monte del Estado Serpentinized Peridotite Belt, Guanajibo Serpentinized Peridotite Belt, Yauco Formation, Maricao Formation, Two Pyroxene Basalt, Sabana Grande Formation, El Rayo Formation, Juana Diaz Formation, and Ponce Limestone.; The study area is characterized by submarine volcanism and deep marine sedimentation showing the contemporaneously evolutionary interrelationship between back-arc rifting and basin evolution. Subsequent subaerial volcanism, associated with fringing carbonate platforms, provided volcanic and carbonate sediments on the slope by gravity flows and sediment bypassing during the Cretaceous.; Tectonism during the late Maestrichtian and early Paleocene deformed the Cretaceous arc forming an angular unconformity between the El Rayo and Jicara Formations. Subsequently, deformation during the early-mid Tertiary formed northwest and northeast trending folds and faults. Exposure of Cretaceous and early Tertiary age rocks resulted in deposition of clastic and carbonate rich units of mid-Tertiary age.