Geochronologic Evidence for the Evolution of the Greater Antilles

Abstract:

The Greater Antilles islands of Cuba, Hispaniola, Puerto Rico, and Jamaica preserve most of a fossil convergent margin that records subduction of the North American plate beneath the Caribbean plate and collision in Late Cretaceous-Eocene time. The Greater Antilles Arc (GAA) formed as a convergent margin on the northern Caribbean Plate and operated for about 80 m.y., from the Early Cretaceous until the final collision in Eocene time. The “soft” collision between GAA and Bahamas platform preserved much of the fossil convergent margin. This fossil convergent margin represents an excellent natural laboratory for studying the formation and evolution of an intra-oceanic convergent margin, however systematic study is hindered by national boundaries, political tension, poverty, and intense tropical weathering. We compiled radiometric ages for the igneous and metamorphic rocks of this region and assigned these to a simple fourfold subdivision of the GAA: forearc mélange belt, ophiolite, magmatic arc, and retro-arc metamorphic belt to better understand the evolution of the GAA, from subduction initiation through maturity and demise. The data show that the southwest-ward subduction system started in Early Cretaceous and ceased in Paleogene, further study on the ophiolite and volcanic arc would provide a better resolution on the age and location of the subduction initiation. The database presented here is intended to help overcome some of the obstacles and motivate systematic study of the GAA.