Age and origin of the Paramillos de Uspallata Pb-Zn-Ag vein deposit in the Cuyo basin, Argentina: Constraints from structural controls and isotopic evidence

Abstract

The Paramillos de Uspallata deposit, located in the Cuyo rift basin, is a Pb–Zn–Ag vein deposit hosted by Mesozoic Triassic volcano-sedimentary sequences. In the present study, new geological and isotopic data is used to constrain the age, source and structural controls of the ore forming fluids. The isotopic data suggest a Middle Cretaceous age for the mineralization and that mineralizing fluids were formed from a mixture of sources that includes the Permian volcanic rocks from the basin basement and the Triassic basalts, with Pb (and Sr) isotopic composition typical of the upper crust. Regional structural analysis allowed to conclude that the veins formed within large-scale reactivated structures that affect the basin basement. Local structural analysis showed that the mineralization was controlled by extensional and shear-extensional WNW-ESE to NW-SE and shear E-W trending structures. Kinematic analyses performed in the veins evidenced a transtensional environment with a NE extension direction and E-W dextral shear. In this scenario fluids were channeled by a strike-slip-faulting system connected with a deep weakness zone during the beginning of the Andean Orogeny. This study provides new insights into the genesis and the geodynamic scenario of Pb–Zn–Ag vein deposit.