Comparisons of the 2005 Geologic Map of North America with the 1965 Map, Areas 5-7
5. The western Caribbean, Cuba, and parts of Central America
The 1965 map shows the on-land geology in this view in considerable detail, but without the concept of plate tectonics and the availability of sea-floor geology it was virtually impossible to make any sense of the complex geology of the Caribbean region. Modern tectonic interpretations are still being debated, but some general features are reasonably well established:
- The Maya block (A) is a sediment-draped continental fragment that reached its present position as North America separated from South America in the Early Jurassic during the breakup of Pangea.
- The Caribbean plate (B) is largely composed of thick and buoyant oceanic crust that originated in the Pacific as part of the Farallon plate in the Late Cretaceous and began moving northeastward into the widening gap between North and South America shortly thereafter.
- Cuba, Jamaica, Hispaniola, and Puerto Rico are parts of the Greater Antilles Arc (C), a subduction-related magmatic arc that formed along the northern boundary of the Caribbean Plate in the Late Cretaceous and moved northeastward with the plate. The Chortis block (D) is a continental fragment perhaps derived from western Mexico that was also carried along with the Caribbean plate. It is now juxtaposed with the Maya block along the Motagua shear zone (E) which marks the suture between the North American and Caribbean plates.
- Cuba was separated from the Greater Antilles arc by back-arc spreading during the Late Cretaceous and Paleocene and became part of the North American plate. A new strike-slip plate boundary between the North American and Caribbean plates developed along the complex group of strike slip-faults that extends from the Motagua shear zone northeastward past the eastern tip of Cuba. The Cayman spreading center (F) developed in the Early to Middle Eocene as a connection between two of the major transform faults in this zone.
Northeastward movement of the Caribbean plate relative to North America since development of the spreading center is thought to have been as much as 1000 km.
- The impact that formed the 170-km-wide Chicxulub structure (G) at the northern tip of the Yucatan Peninsula took place as Cuba was being transferred from the Caribbean plate to the North American plate.
Return to comparisons of map areas 5-7.
ESP Team Research Activities | ESP Team home page
U.S. Department of the Interior | U.S. Geological Survey
