2. Western Caribbean Tectonics

Despite 50 years of study, the evolution of the western Caribbean Plate region is still debated and there are three possible end-members: (1) Pacific model where the western Caribbean lithosphere is derived from the eastern Pacific and the northern and southern Caribbean Plate boundaries connect directly west to the Middle America Trench at the western Caribbean Plate boundary, (2) In-situ model where the western Caribbean lithosphere is derived from depth and the northern and southern Caribbean Plate boundaries terminate in a broad zone of extension in the western Caribbean Plate, and (3) Pirate model where the western Caribbean lithosphere is derived from the southern and northern margins of North and South America, and the northern and southern Caribbean Plate boundaries have either accommodated convergence themselves, or have curved to the north and south prior to reaching the Middle America Trench. Analysis indicates all models have been important for the evolution of the western Caribbean at different times but the Pirate model may have been dominant during the Cenozoic. The Pirate model resolves the absence of fault connections between the northern and southern boundaries of the Caribbean Plate with the Middle America Trench that are essential for the Pacific model and the > 1,100 km of net strike-slip displacements inferred across the northern and southern Caribbean margins that are unexplained by the in-situ model. In the Pirate model, North and South American material is inferred to have rotated into the trailing edge of the Caribbean Plate across the western Caribbean Plate corners.