Mineralogy, geochemistry and sulfur isotope characterization of Cerro de Maimon (Dominican Republic), San Fernando and Antonio (Cuba) lower Cretaceous VMS deposits: Formation during subduction initiation of the proto-Caribbean lithosphere within a fore-arc

摘要

The volcanic-arc Lower Cretaceous Maimon (Dominican Republic) and Los Pasos (Cuba) Formations, representative of the oldest magmatism recorded in the Caribbean island arc, host most of the known volcanogenic massive sulfide (VMS) deposits in the Greater Antilles. On the basis of new lithogeochemical data, basalts of the Maimon Formation are classified as fore arc basalts (FAB), boninites and less abundant low-Ti (LOTI) and normal islandarc tholeiites (TAT), and those of the Los Pasos Formation as LOTI and IAT. Felsic volcanics from the two formations are geochemically analogous and present mantle-type (M-type), boninitic and tholeiitic signatures, classifying as Fly-type, typical of post-Archaean VMS-bearing juvenile volcanic suites. This lithogeochemical data is indicative of formation in a fore-arc environment just after subduction initiation in association with initial extensional regimes and associated boninitic and tholeiitic melts that originated in the shallow mantle. Within this tectonic framework, rocks of the Los Pasos Formation and associated VMS deposits likely formed at a slightly later stage than those of the Maimon Formation.