Biostratigraphy and Its Implications for the Early Tectonic Evolution of the Great Arc of the Caribbean

Cretaceous chronostratigraphy is largely based on ammonites, inoceramid bivalves, planktic foraminferans and calcareous nannofossils. This makes interpretations of many shallow-water Caribbean successions difficult, because they lack these fossil groups. In consequence, tectonic models for the evolution of the Caribbean Plate have largely been based on best guesses of ages using a combination of limited biostratigraphy and older (K-Ar) radiometric ages. The progressive development of new biostratigraphic schemes using tropical fossil organism (such as, rudist bivalves and larger benthic foraminifers) and particularly their correlation with the chronostratigraphic scheme using rare occurrences of traditional fossils and ages derived from Sr isotopes, allows a new look at the evolution of the Caribbean Plate. The earliest history of arc-volcanism in the Caribbean is represented by tholeiitic basalts in Jamaica that are overlain by rudist-bearing, Hauterivian limestones. These Jamaican successions can be compared to successions elsewhere in the Greater Antilles, and suggest that there was a progressive west-to-east change in arc chemistry from thoeiitic basalts to calc-alkalline volcanics, with the change occurring later progressing eastwards. This change in arc chemistry is inconsistent with current models of arc polarity reversal in the Aptian and requires careful analysis. These new data are presented in this paper and used to constrain potential scenarios for the early history of the Great Arc of the Caribbean.