The Forgotten Paleocene-Middle Eocene Sierra Maestra-Cayman Ridge Volcanic Arc and the Origin of the Caribbean Plate

In the Early Paleocene (Danian), a new east-west trending submarine volcanic arc was born in SE Cuba (Turquino-Cayman Ridge volcanic arc) on top of the Cretaceous volcanic terrane and its sedimentary cover. Several thousands meters of effusive and pyroclastic rocks, with marine sedimentary intercalations crop out in the Sierra Maestra mountains. Its corresponding back arc basin, lays to the north. Intruding the volcanic sequence in the Sierra Maestra are a large number of magmatic bodies. Pb/U analyses from zircons in the granitoids yielded ages from 60 Ma (Paleocene) to 48 Ma (Middle Eocene). Westward, the volcanic arc and its back arc basin continues into the Cayman Ridge and the Yucatán basin. A north dipping suduction zone should flank the Turquino-Cayman Ridge arc to the south, and dense oceanic Caribbean crust dived below the arc. Coeval Eocene volcanic arc rocks occur in the Northwestern Peninsula and the Montaignes Noires of Haiti and in Sierra de Neiba and Seibo of the Dominican Republic. If they originally were part of the Turquino-Cayman Ridge arc, then probably this structure was more than 1500 km long. The subducted (Caribbean) oceanic crust must have moved with a strong northward component along the 1000-1500 km long subduction zone of the Turquino-Cayman Ridge arc. In many of the Caribbean evolution models, at this time (Danian-Middle Eocene) the Caribbean plate is moving with a strong eastward component. In the present interpretation, the lithosphere to the north of the Turquino-Cayman Ridge subduction zone was already accreted to the NA plate in the Paleocene, and the southeastern boundary of the NA plate was a north dipping subduction zone.