Northeast- or southwest-dipping subduction in the Cretaceous Caribbean gateway?

Most of the Caribbean plate, which currently lies between the American continents, represents a mantle plume derived 8-20 km thick Cretaceous oceanic plateau that was formed in the Pacific region and moved eastwards. The northern islands of the Caribbean are largely made up of a dismembered island arc that was located along the western entrance to the inter-American region (termed the Great Arc of the Caribbean) in the mid-late Cretaceous. Importantly, the timing of Caribbean lithospheric movement into the inter-American region is controversial, with one hypothesis advocating that it happened in the Hauterivian-Albian (132.9-100.5 Ma), and a second hypothesis proposing the Turonian-Campanian (93.9-72.1 Ma). In order to investigate this problem, island arc rocks are studied on St. John, U.S. Virgin Islands, which are Barremian (127 Ma) to Santonian (83.6 Ma) in age. Immobile trace element and Nd-Hf radiogenic isotope ratios demonstrate that the arc rocks are derived from the partial melting of an Atlantic MORB-like mantle source region that has been variably contaminated with slab-derived fluids composed of continental detritus and slow sediment clay components. We argue that the lack of a mantle plume geochemical signature in the rocks supports the idea that the movement of Caribbean lithosphere into the inter-American region occurred in the late Cretaceous (post-Santonian) due to a subduction polarity reversal caused by collision of the Caribbean oceanic plateau with the Great Arc of the Caribbean.

Automated summary

The article discusses the formation and movement of the Caribbean plate, finding through rock studies on Saint John Island that the movement of the Caribbean region may have occurred in the Late Cretaceous, likely due to a subduction polarity reversal caused by collision with the Great Arc of the Caribbean.