The geochemistry of the Maimón Formation (Central Cordillera, Dominican Republic) revisited

Abstract

RESUMENLos materiales volcánicos de la Formación Maimón, metamorfizados en facies de esquistos verdes, son representativos del magmatismo más antiguo registrado en el arco-isla del Cretácico del Caribe. A partir de nuevos datos geoquímicos de roca total y mediante el uso de elementos traza inmóviles (elementos de alto potencial iónico -HFSE, tierras raras -REE), se reconoce el predominio de protolitos basálticos y una menor proporción de rocas de composición intermedia y ácida. Geoquímicamente, los protolitos basálticos han sido clasificados como boninitas, toleítas de arco de isla pobres en Ti y LREE, toleítas de arco de isla pobres en Ti normales y escasas toleítas de arco de isla normales. Las rocas ácidas presentan claras afinidades boniníti-cas y toleíticas y pertenecerían al tipo M (derivadas del manto). La geoquímica de las toleítas pobres en Ti y LREE permite su clasificación como FAB (Fore-Arc Basalts, i.e. basaltos de ante-arco), término recientemente acuñado para describir toleítas con rasgos de MORB (basaltos de dorsal centro-oceánica) identificados en el ante-arco de Izu-Bonin-Mariana. La presencia de FAB y su correlación estratigráfica con boninitas son indicativas de formación en un contexto de ante-arco durante los primeros estadios magmáticos en un régimen extensional ligado al inicio de la subducción y el nacimiento del arco-isla. La Fm. Maimón puede representar la sección superior (volcánica) de una ofiolita tipo "inicio de subducción" .

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

“…In the studied rocks of the Maimón Formation, increasing AI and CPPI values from the "least altered rhyolites, dacites and basalts" (least altered box in Fig. 3A) are indicative of chloritization, sericitization and sulfide mineralization (pyrite), that along with silicification were recognized in the petrographic study by Torró et al (2015). Most of the rocks studied from the Los Pasos Formation for lithogeochemistry were sampled far from the mineralized centers; however, mafic rocks from this formation show trends towards sericitization and carbonatization and felsic rocks record albitization, both trends probably related to spilitization and keratophiritization processes.…”

“…Rocks from the Maimón and Los Pasos Formations have undergone extensive sea-floor metamorphism as well as hydrothermal alteration linked to the formation of the VMS deposits Díaz de Villalvilla, 2003;Torró et al, 2015). As a result, a number of elements (Si, K, Na, Ca, Mg, Fe, Rb, Ba, Sr) (Fig.…”

The Discovery of the Romero VMS Deposit and Its Bearing on the Metallogenic Evolution of Hispaniola during the Cretaceous

“…The Maimón formation, located in a median belt in the Bonao tectonic block [23,35], extends to the eastern limit of the Cordillera Central. Mafic-felsic, bimodal metavolcanic rocks of the Maimón formation, with forearc basalt (FAB), boninite and low-Ti island-arc tholeiite (IAT) signatures, record a lithogeochemical progression that is characteristic of subduction initiation ophiolites [37,[39][40][41]. The age of the Maimón formation has been assigned to the Early Cretaceous based on U-Pb zircon dating [42] and their geochemical similitude to other arc-related rock units of the Early Cretaceous age [6,33,38,40,41,43,44].…”

“…Mafic-felsic, bimodal metavolcanic rocks of the Maimón formation, with forearc basalt (FAB), boninite and low-Ti island-arc tholeiite (IAT) signatures, record a lithogeochemical progression that is characteristic of subduction initiation ophiolites [37,[39][40][41]. The age of the Maimón formation has been assigned to the Early Cretaceous based on U-Pb zircon dating [42] and their geochemical similitude to other arc-related rock units of the Early Cretaceous age [6,33,38,40,41,43,44]. Thrust over the Maimón formation is the non-metamorphic Los Ranchos formation, which extends eastwards across the Dominican Cordillera Oriental and comprises mafic-felsic bimodal plutonic and volcanic series and volcaniclastic and terrigenous deposits.…”