Abstract

MAFFINI, María Natalia et al. Mesothermal Pb-Zn-Ag-Au veins emplaced east of the Cerro Áspero batholith, Sierra de Comechingones, Córdoba. Ser. correl. geol. [online]. 2012, vol.28, n.2, pp.93-106. ISSN 1666-9479.

This paper presents a descriptive model of mesothermal Pb-Zn-Ag-Au veins hosted in mylonitic rocks of the Guacha Corral shear zone, located ~2 km east of the Cerro Aspero Batholith (BCA) in the Sierra de Comechingones, Córdoba. The mineralization occurs as steep-dipping tabular veins with a marked structural control and discontinuous longitudinal development in a NW-SE direction reaching 8 km. The major veins are 0,2-1 m thick and are associated with profuse veinlets. They consist mainly of quartz containing a variety of sulfides, oxides and carbonates, of both hypogene and supergene origin. The largest tenors of precious metals were found in the oxidation zones of the deposits, with values ranging from 1.63 to 3.57 g/t Au and 149 to 216 g/t Ag. Hydrothermal alteration of the host rocks is common and highly developed in many areas around the veins. It mainly consists of penetrative sericitization and moderate to strong hematization that develops in tension veins. Silicification and carbonation occur subordinately. Field relations, structural evidences and microstructural and petrographic analysis suggest that the emplacement of these deposits occurred after the last deformation phase of the Guacha Corral Shear Zone, under a simple shear deformation condition. The relations between the Pb-Zn-Ag- Au deposits and the BCA has not been completely established. Current research is mainly aimed at determining the influence of devonian magmatism as a possible mineralization metallotect.

Keywords : Mesothermal veins; Structural control; Precious metals; Guacha Corral shear zone; Sierra de Comechingones.

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