Geochemistry of the Mabujina Complex, Central Cuba: Implications on the Cuban Cretaceous Arc Rocks

摘要

The margins of the Caribbean plate are marked by Cretaceous island-arc basalts associated with accreted fragments of the Cretaceous Colombian Caribbean oceanic plateau. In Cuba, the Cretaceous volcanic island-arc rocks are in fault contact with the Mabijina complex, interpreted as an oceanic Jurassic to Early Cretaceous arc basement with local island-arc rocks. The Cuban Cretaceous island arc consists of Early to Late Cretaceous volcanic series associated with limestones. While the pre-Albian arc rocks consist of tholeiitic basalts and rhyolites, the post-Albian volcanic series is characterized by calc-alkaline andesites. The Cretaceous lavas have Sr and Nd isotopic compositions similar to the intraoceanic arcs, and the Pb isotopic initial ratios are close to the East Pacific Rise mid-ocean ridge basalt field. According to our data, the Mabujina arc rocks are tholeiites and calc-alkaline basalts, developed in a Jurassic and/or Early Cretaceous intraoceanic island arc. Their Nd, Sr, and Pb isotopic compositions indicate that they derive from a depleted mantle source contaminated by sedimens. This subduction magmatism is not related to the classic Early Cretaceous Caribbean tholeiitic series but is similar to the Late Jurassic to Early Cretaceous Guerrero arc terrane from Mexico and may represent its southernmost extension. Thus, the different tectonic units of central Cuba cannot be easily correlated with those of Hisplaniola. Our data also indicate that two different island arcs were tectonically juxtaposed in central Cuba: the classical Lower and Upper Cretaceous suites of the Greater Antilles arc and a Jurassic to Early Cretaceous island-arc suite with a Pacific provenance.