Geology and tectonic evolution of the northern Caribbean margin
The northern Caribbean plate margin is a complex orogen that has developed since at least Jurassic time as a result of convergent and transcurrent tectonics. Early convergence produced an island-arc structure that was modified by Tertiary strike-slip movements. Many hypotheses have been proposed to explain the tectonic evolution of the region, but as our knowledge of the area has progressed, few have survived rigorous testing. Even today, the models based on modern theories of plate tectonics are still vigorously debated, and no single hypothesis has met with widespread acceptance.
In broad terms, the northern Caribbean margin is an eastwest- trending, dissected and segmented ridge structure that separates the Caribbean basin from the American plate to the north. The modern margin is tectonically active and is characterized by intermediate crustal thicknesses, high seismicity, large Bouguer gravity and magnetic anomalies, late Cenozoic volcanic activity on central Hispaniola, and active oceanic volcanism in the Cayman trough spreading center.
Principal geographic features of the northern margin are shown on Plate 1. The ridge structure of the Greater Antilles rises above sea level as the four large islands of the Greater Antilles, namely Cuba, Hispaniola, Puerto Rico, and Jamaica. The Virgin Islands archipelago of about 100 islands forms the eastern extremity of the Greater Antilles, and is terminated to the east by the Anegada fault, which is a comparatively young feature (probably early Tertiary). Many consider that the eastern Greater An tilles formerly continued as a curved arc to the southeast, at least as far