Estructura del cinturón de pliegues y cabalgamientos de Peralta, República Dominicana

Abstract

Most of the geotectonic units involved in the evolution of the Northern part of the Caribbean Plate can be identified in a geological cross-section through the southern-central part of the Hispaniola Island (South of the Dominican Republic). The cross-section includes from N to S: remnants of the old Caribbean ocean (Loma Caribe Peridotites and Duarte Fm of Upper Jurassic-Lower Cretaceous age), rocks of the Primitive volcanic Island Arc (Lower Cretaceous), the Circum-Caribbean Island Arc (Upper Cretaceous to Eocene), the Peralta thrust and fold Belt and the Azua Neogene Basin. The structure consists of an imbricate thrust system with associated folds, vergent towards the South, that overthrusts the Azua Basin. The thrust system evolved in a forward propagating sequence. The first thrust sheets of the Circum-Caribbean Island Arc possibly formed in Upper Eocene times during sedimentation of the Ocoa Fm in the foredeep (area of the Peralta Belt). Ocoa Fm has a syntectonic character and is associated with the uplift of the Central Mountain Range. Thrusting continued through Oligocene times progressing towards the South. By Lower Miocene times, the Circum-Caribbean Island Arc overthrusts the Peralta Belt (Frontal Thrust of the Tireo Fm). Thrusting in the Peralta Belt continued until Plio-Pleistocene times, as indicated by the age of the rocks in the footwall to the Peralta Belt Frontal Thrust. From Miocene times thrusting was coeval with wrenching that progressively became the dominant tectonic style in the region. The Eocene-Oligocene sedimentary sequences of the Peralta Belt were deposited in a back-arc basin that was subsequently deformed during the change in subduction direction that took place in the northeastern part of the Caribbean Plate in Neogene times. The Neogene Peralta Thrust and Fold Belt may be caused by the indentation of the Beata Ridge into the Circum-Caribbean Island Arc. In this context, the eastern part of the Beata Ridge may have acted as a transform boundary separating the Los Muertos trench from the Peralta Belt. The Peralta Belt accumulated part or all the shortening laterally equivalent to that in Los Muertos accretionary prism.