El depósito volcanogénico de Cu-Zn-Pb-Au El Cobre, Cuba Oriental: estructura y mineralogía

Abstract

The “El Cobre” deposit is hosted by the volcanosedimentary series of the Western Cuba Paleogene volcanic island arc. Several mineralization styles have been distinguished: stratiform, stratabound, and veins. The stratiform deposits (anhydrite, barite or c ryptomelane) were formed by precipitation from hydrothermal fluids in the sea floor. The vein mineralization is the root zone of the stratiform deposits and displays an stockwork - like morphology in the uppermost levels; at the deeper levels the mineralized zone becomes thinner. Pyrite and chalcopyirite are the most abundant sulphides in these veins in association with quartz, except in those veins located in the uppermost levels, where sphalerite associated with anhydrite is dominant. The associated hydrothermal alteration assemblages are chloritization and silicification in the deeper sectors; in surficial levels sericitization and kaolinization occur. The stratabound mineralization is contemporaneous with the veins and is produced by replacement of the Paleogene series: limestones in the lower part and the sulphate stratiform body at the uppermost. Based on the above mineralization styles, and according to the syngenetic character of these deposits with the volcanosedimentary rocks of the Middle Sequence of the El Cobre Group, we propose a volcanogenic (exhalative) formation model in a island arc geodynamic setting, similar to the Kuroko model.