DOMOS VOLCÁNICOS Y MINERALIZACIÓN DE ORO EN EL DISTRITO PUEBLO VIEJO, REPÚBLICA DOMINICANA

Abstract

Gold mineralization in the Pueblo Viejo district, Dominican Republic is spatially and temporallyrelated to a series of Early Cretaceous volcanic domes. Separate but overlapping hydrothermal cells, centeredon the domes, together deposited more than 40 million ounces of gold, 240 million ounces of silver, 3 milliontonnes of zinc, and 0.4 million tonnes of copper. Two principal deposits (Moore and Monte Negro) and a number of smaller deposits (Cumba, Mejita, Upper Mejita, Banco V, Arroyo Hondo I and II) have contributed oresince mining commenced in 1975.Geologic mapping in the Pueblo Viejo District has identified a series of at least seven volcanic centers that interfinger, overlap, and are interbedded with locally derived epiclastic sediments. These volcanic centers are centered on previously-unrecognized volcanic domes that vary from andesite to dacite in composition. Epiclasticvolcanic sediments surround the domes and reflect the composition of the local source rock. A dacite porphyrydome in the Moore deposit is surrounded by epiclastic sediments that contain detrital quartz eyes and debrisflows of dacite porphyry. Andesite domes in the Monte Negro, Cumba and Mejita deposits are surrounded byepiclastic crumble breccias and volcaniclastic sediments.Field relations indicate that volcanic dome emplacement, epiclastic sediment accumulation, hydrothermal alte-ration, and gold mineralization were coeval events. Domes were emplaced in a shallow subaqueous environmenton the flanks of an emergent volcanic edifice. Hydrothermal cells responsible for gold mineralization are controlled by high-angle faults. These same faults influenced the emplacement of volcanic domes, an essential stepin the development of gold ore in the Pueblo Viejo district.