Paper No. 275-15
Presentation Time: 11:35 AM
TECTONIC FRAMEWORK OF CUBA, AND SOME AVENUES OF CONTINUED RESEARCH
Cuba comprises three tectonic domains: 1, the Mesozoic passive margin platforms of eastern Yucatán (Sierra Guaniguanico) and southern Bahamas; 2, an allochthonous Lower Cretaceous-Eocene intra-oceanic arc complex; 3, Paleocene-Middle Eocene debris flows and foredeep deposits recording arc-platform collision after S-dipping subduction of Proto-Caribbean crust. Pre-collision paleogeography of the now-subducted Proto-Caribbean Seaway is resolved from Atlantic and Gulf of Mexico opening kinematics. The Cuban arc led the Caribbean Plate at least 1500 km from the Pacific to the Bahamas-Yucatán suture. The Paleogene part of this migration was assisted by intra-arc extension in Yucatán Basin. Since mid-Eocene, Cuba, Yucatán Basin and Cayman Ridge have moved west by ~1200 km (local mantle reference frame) with North America, separating them from Hispaniola and the Caribbean Plate along the Oriente Fault, and allowing Cayman Trough to open. This view of Cuba’s geology and evolution has stood for some 30 years, but several issues need further resolution, some of which are: 1, whether basement beneath the Bahamian Great Bank is thinned continental or thick magmatic crust is unknown; 2, an explanation for why arc magmatism ceased in central Cuba in the Maastrichtian is unclear, although central Cuba may simply have moved off the magmatic axis during opening of Yucatán Basin. 3, the reconstruction of the Hispaniolan and Cuban arc segments remains loosely defined; some models put >400km of the Cayman Trough’s 1200 km of movement on Oriente Fault, implying that Hispaniola is a distinct arc from Cuba, but this unlikely implication can be avoided if 800km of the Cayman’s motion passed south of Hispaniola’s arc axis. 4, models for the opening of Yucatán Basin vary from NW-SE extension to sinistral shear on NE-trending transforms across the basin, implying different driving forces of the Cuban collision. 5, because North America dominated plate motions relative to the local mantle during collision, Proto-Caribbean slab drop off was required for relative plate motion to continue, but Paleogene isostatic adjustments in Cuba have not been interpreted in light of this process. Much can learned about the northern Caribbean from future work in Cuba, including petroleum potential in Florida Straits which is not discussed here.