The geologic mapping and history of the Guánica quadrangle, southwestern Puerto Rico

Abstract

The geologic mapping of the Guánica Quadrangle provided a better understanding of the geology of the southwestern Puerto Rico. Six formations were defined and described: 1) the Santonian or older Basaltic Andesite

The geologic mapping of the Guánica Quadrangle provided a better understanding of the geology of the southwestern Puerto Rico. Six formations were defined and described: 1) the Santonian or older Basaltic Andesite; 2) the Santonian to Campanian Parguera Limestone; 3) the Campanian Ciénaga Conglomerate; 4) the Late Paleocene Jícara Formation; 5) the Oligocene Juana Díaz Formation; and 6) the Miocene Ponce Limestone. There are three major events that control the structural geology of the area. The first event is the post-Ponce Limestone deformation; the second event is the post-Juana Díaz Formation-pre-Ponce Limestone deformation and the third event is the pre-Juana Díaz Formation deformation. Deposition in the quadrangle began with the Basaltic Andesite followed by deposition of the Parguera Limestone and the Ciénaga Conglomerate. The late Paleocene Jícara Formation was deposit unconformably over the Cretaceous rocks followed by the deposition of the Oligocene Juana Díaz Formation and Miocene Ponce Limestone. The geologic mapping of the Guánica Quadrangle provided a better understanding of the geology of the southwestern Puerto Rico. Six formations were defined and described: 1) the Santonian or older Basaltic Andesite; 2) the Santonian to Campanian Parguera Limestone; 3) the Campanian Ciénaga Conglomerate; 4) the Late Paleocene Jícara Formation; 5) the Oligocene Juana Díaz Formation; and 6) the Miocene Ponce Limestone. There are three major events that control the structural geology of the area. The first event is the post-Ponce Limestone deformation; the second event is the post-Juana Díaz Formation-pre-Ponce Limestone deformation and the third event is the pre-Juana Díaz Formation deformation. Deposition in the quadrangle began with the Basaltic Andesite followed by deposition of the Parguera Limestone and the Ciénaga Conglomerate. The late Paleocene Jícara Formation was deposit unconformably over the Cretaceous rocks followed by the deposition of the Oligocene Juana Díaz Formation and Miocene Ponce Limestone.

El mapa geológico del cuadrángulo de Guánica resultó en un mejor entendimiento de la geología del suroeste de Puerto Rico. Durante el curso del trabajo de campo seis formaciones fueron definidas y descritas: 1) la Andesita Basáltica del Santoniano; 2) la Calizas de Parguera del Santoniano al Campaniano; 3) el Conglomerado de Ciénaga del Campaniano; 4) la Formación Jícara del Paleoceno; 5) la Formación Juana Díaz del Oligoceno; 6) las Calizas de Ponce del Mioceno. Tres eventos mayores controlan la geología estructural del cuadrángulo. El primer evento es la deformación post-Caliza de Ponce ; el segundo evento es la deformación post-Formación Juana Díaz-pre-calizas de Ponce y el último evento de la deformación pre-Formación Juana Díaz. La deposición en el cuadrángulo comenzó con la Andesita Basáltica y continúo con la deposición de la Caliza de Parguera y el Conglomerado de Ciénaga. La Formacíon Jícara fue depositada desconformemente sobre las rocas del Cretácico seguida por la deposición de la Formación Juana Díaz del Oligoceno y la Caliza de Ponce del Mioceno.