Integration of tectonic geomorphology and crustal structure across the active obliquely collisional zone on the island of Hispaniola, northeastern Caribbean

Abstract

AbstractActive tectonic deformation and seismicity of Hispaniola define a 250 km-wide, oblique collisional zone between the Bahamas, the island arc of Hispaniola and the Caribbean Large Igneous Province (CLIP). To reflect how collision is accommodated within Hispaniola, we calculate river normalized steepness and terrain surface roughness to reveal the areas of the most active uplift within central and western Hispaniola compared to eastern Hispaniola. We use gravity modelling to show thickness variations in the main crustal types in the obliquely convergent zone: (1) 33–45 km-thick arc crust in central and western Hispaniola; (2) 15–25 km-thick oceanic crust beneath the Bahamas north of Hispaniola; (3) 5–8 km-thick Atlantic oceanic crust NE of Hispaniola; and (4) 6–16 km-thick CLIP south of Hispaniola. Intermediate to deep earthquakes beneath eastern Hispaniola indicate active southwestward subduction of normal oceanic crust and northward subduction of the CLIP. We interpret that the west-to-east geomorphological and crustal variations within Hispaniola to be the result of an along-strike transition from crustal shortening without subduction between the Bahamas and arc crust in central and western Hispaniola to subduction of the North American and Caribbean plates beneath eastern Hispaniola. Crustal shortening in central and western Hispaniola produces thrust-fault-bounded basins with sufficient clastic sedimentary infill to produce hydrocarbon maturity.