Accretionary Prism and Forearc Deformation Driven by the Beata Ridge Indentation in Southern Hispaniola: Insights From the Offshore San Pedro Basin

Abstract

The Cretaceous–Eocene island arc of Hispaniola is currently shortened between the Bahamas carbonate platform to the north and the thickened crust of the Caribbean Large Igneous Province (CLIP) to the south. Within this transpressional setting, the 15–22-km-thick, ∼100-km-wide Beata Ridge (BR), the thickest portion of the CLIP, acts as a mechanically strong, tectonic indenter controlling on upper-plate deformation in Hispaniola. Integration of marine seismic, multibeam bathymetry, gravity and magnetic anomalies, and onshore geological data reveals a ∼140-km-wide counterclockwise rotation belt in central Hispaniola and coeval clockwise rotations in the offshore San Pedro Basin (SPB). The tectonostratigraphic evolution of the SPB provides a continuous Cenozoic record of indentation-related deformation, documenting the transition from a Late Cretaceous back-arc basin to a Late Eocene–present forearc basin associated with the Peralta–Muertos accretionary prism. Seismic stratigraphic analysis identifies key indicators of indentation, including rapid subsidence, angular unconformities, fault reactivation, and progressive rotation of Miocene–Pliocene depocenters, which together constrain the timing and landward propagation of deformation. Our results suggest that indentation began earlier than previously proposed, likely in the middle Miocene, and evolved progressively over time. The observed deformation patterns are consistent with models of narrow (100–400 km) arc–ridge indentation systems, where the indenter width controls the curvature and extent of upper-plate deformation. These findings demonstrate that the Beata Ridge governs the kinematic evolution of the Hispaniola forearc system and provide a framework for understanding deformation in confined arc–ridge collision zones worldwide.