Abstract
The recently discovered Romero deposit, located in the Tres Palmas district, Cordillera Central of the Dominican Republic, has probable reserves of 840,000 oz gold, 980,000 oz silver and 136 Mlb copper. Mineralization is hosted by intermediate volcanic and volcaniclastic rocks of the lower stratigraphic sequence of the Cretaceous Tireo formation. The andesitic host rocks yield a U-Pb zircon concordia age of 116 ± 10 Ma. Au–Ag–Cu(–Zn) mineralization is divided into: (1) an upper domain with stacked massive sulfide lenses and sulfide dissemination within a 20-m-thick level of massive anhydrite-gypsum nodules, and (2) a lower domain with a high-grade stockwork mineralization in the form of cm-scale veins with open space fillings of fibrous silica and chalcopyrite, sphalerite, pyrite (+electrum ± Au–Ag tellurides). The δ34S values of sulfides from the upper (−7.6 and +0.9‰) and lower (−2.4 and +5.6‰) domains are consistent with a heterogeneous sourcing of S, probably combining inorganically and organically induced reduction of Albian-Aptian seawater sulfate. Despite this, a magmatic source for sulfur cannot be discarded. The δ34S (+19.2 and +20.0‰) and δ18O (+12.5 and +14.2‰) values of anhydrite-gypsum nodules are also consistent with a seawater sulfate source and suggest crystallization in equilibrium with aqueous sulfides at temperatures higher than 250 °C. These data point to a classification of Romero as a volcanogenic massive sulfide (VMS) deposit formed in an axial position of the Greater Antilles paleo-arc in connection with island arc tholeiitic magmatism during a steady-state subduction regime. Circulation of hydrothermal fluids could have been promoted by a local extensional tectonic regime expressed in the Tres Palmas district as a graben structure.
Highlights
Exploration for gold and copper is currently being carried out in Early Cretaceous-to-Eocene age volcanic belts on Hispaniola, an island divided between the Dominican Republic and Haiti [1,2].Arc-related rocks from the Cordillera Central of the Dominican Republic and its extension in the Massif du Nord in Haiti have been, and continue to be, the most intensively prospected
3), which belong to the and volcaniclastic rocks of intermediate and basic composition (Figure 3), which belong to lower volcanic sequence of theofTireo formation
The newly discovered Romero deposit is hosted by volcanic and volcaniclastic rocks of the lower sequence of the Tireo formation, and a hosting andesite has been dated at 116 ± 10 Ma
Summary
Exploration for gold and copper is currently being carried out in Early Cretaceous-to-Eocene age volcanic belts on Hispaniola, an island divided between the Dominican Republic and Haiti [1,2].Arc-related rocks from the Cordillera Central of the Dominican Republic and its extension in the Massif du Nord in Haiti have been, and continue to be, the most intensively prospected. Exploration for gold and copper is currently being carried out in Early Cretaceous-to-Eocene age volcanic belts on Hispaniola, an island divided between the Dominican Republic and Haiti [1,2]. Current exploration follows previous sustained efforts from the 1970s that led to the discovery of the Cerro de Maimón volcanogenic massive sulfide (VMS) and the world-class Pueblo Viejo epithermal deposits, both of which are currently in production (Figure 1) [2,3,4,5,6,7,8]. The value of Dominican export of mineral resources in 2017 was US$1766 M, of which gold was the main commodity with a value of US$1456.7 M [9]. Haiti currently has no metallic mineral exports.
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