RELACIÓN ENTRE MINERALIZACIÓN DE Cu Y BITUMEN EN EL PROSPECTO LA CUPROSA, DORSAL DE HUINCUL, NEUQUÉN

MAXIMILIANO PAZ; JOSEFINA M. PONS; ADOLFO GIUSIANO; MARIA CECILIA CÁBANAS; FRANCHINI MARTA; ESTEBAN GONÁLE; AGNES IMPICCINI,; ANA LAURA RAINOLDI

Revista de la Asociación Geológica Argentina

Asociación Geológica Argentina

Lugar: Capital Federal; Año: 2016 vol. 73 p. 563 - 581

1853-7138

La Cuprosa is a Revett or sandstone sub-type sediment-hosted stratiform Cu deposit of the Portezuelo Formation (Neuquén Group), located over the Aguada Baguales oil field, Huincul Ridge. Its diagenetic story can be subdivided in: diagenesis, mineralization and telogenesis. During early diagenesis hematite and kaolinite precipitated from meteoric waters. Early oxidation of hydrocarbon in depth, rising CO2 and mixing with meteoric waters produced calcite I precipitation. The incoming of liquid hydrocarbons and redox reactions with the rock generated: clasts and previous cements dissolution, porosity increase, smectite ± chlorite and sintaxial micro-quartz cements, reduction of Fe3+ to Fe2+ to form pyrite (± chlorite), and later analcime and baroque calcite II precipitation. Circulation of slightly oxidizing, neutral, Cu-rich basinal brines could extract Cu from subjacent red beds and igneous rocks, transport it in solution, and precipitate Cu-Fe sulfides in contact with hydrocarbons. These sulfides replaced pyrite and generated partial iron remobilization to the periphery of the mineralization zone. Andean tectonic during the Miocene produced the telogenetic processes: calcite III formation, and Cu sulfides replacement by malachite> chrysocolla> azurite> brochantite? and pyrite by hematite> goethite. The bleaching distribution mapped by satellite imagery analysis and the zonation of the alteration can be utilized for hydrocarbon migration and similar stratiform Cu deposits studies.