Petrographic and litho-geochemical characterization of the VMS deposit at El Roble mine, Colombian Western Cordillera


El Roble Mine (Cu-Au) siliciclastic-mafic volcanogenic massive sulfide (VMS) deposit, is located at El Carmen de Atrato, Chocó, Colombian Western Cordillera. This 4-million-ton VMS occurs replacing black chert rocks between Upper Cretaceous volcanic Barroso Formation and Upper Cretaceous Urrao member of Penderisco Formation. Major, trace and REE elements, indicate that there are at least two different mantle sources (E-MORB and N-MORB) from the volcanic Barroso Formation(?). Then the close relation between black chert unit and E-MORB related basalts may have leaded the VMS mineralization. The 2D geochemical vector modelling from drill-cores around “Zeus” ore body shows positive correlated anomalies for the AI (Alteration Index), CCPI (Chlorite Carbonate Pyrite Index), Tl and MgO with the presence of hyaloclastites, becoming important exploration vectors for the VMS at the North Volcanic Zone of the Andean Cordillera. Nevertheless, the Na2O negative anomaly close to the ore body, is not conclusive in such type of VMS due to overprinted hydrothermal alteration closely related to the Cenozoic arc environment.


Palabras clave

VMS, Petrografía