EARLY CRETACEOUS TO PALEOGENE ARC ROCKS OF CUBA

The evolution and development of the Early Cretaceous (∼135 Ma) to Paleogene (∼46 Ma) arc systems in Cuba is the result of intra-oceanic subduction of the proto-Caribbean below Pacific lithosphere (Farallon plate). Volcano-sedimentary and plutonic rocks of predominantly low-K tholeiitic and calc-alkaline to shoshonitic affinity characterize the different island-arc units that occur in tectonic contact above and below ophiolitic rocks (west-central and eastern Cuba), and above the Guaniguanico and Caribeana terranes.

The arc section, especially in central Cuba, is almost complete and records quasi-continuous arc magmatism that developed since pre-middle Hauterivian time (pre ~133 Ma). The oldest arc-related rocks consist of unmetamorphosed primitive bimodal sequences of the Los Pasos Fm and the Mabujina Amphibolite Complex (MAC). Geochemically the Los Pasos Fm includes mostly low-Ti island arc tholeiites, normal island arc tholeiites (IAT) and M-type felsic volcanic rocks with boninitic signatures. The MAC predominantly consists of IAT basalt and basaltic andesite, gabbro and pyroclastic rocks, deformed and metamorphosed up to amphibolite-facies. Several younger intra-oceanic volcanic arc complexes/series unconformably overlie the early Cretaceous IAT lavas and include widespread Albian-Coniacian calc-alkaline and Coniacian-Campanian high-K calc-alkaline/alkaline volcanic rocks. Cretaceous volcanic units in eastern Cuba are basaltic to felsic in composition and have distinct geochemical signatures documenting fore-arc, axial-arc and back-arc environments. Fragments of the Cretaceous volcanic arc (Purial complex) underwent subduction-related metamorphism during the latest Cretaceous. Arc-related granitoid plutons with a wide range of compositions intruded the Cretaceous arc at ~104−75 Ma (Camagüey region) and at ~89−83 Ma in central and eastern Cuba.

The youngest section (Paleocene-Eocene) of the Cuban arc is mainly restricted to eastern Cuba. The magmatic axis of this arc occurs in the Sierra Maestra Mountains and mostly consist of low-K IAT and calc-alkaline lavas, suggesting an immature intra-oceanic arc environment. A large number of calc-alkaline, low- to medium-K tonalite and trondhjemite plutons and hypabyssal bodies intruded the arc sequence from ~60 to 47 Ma.