Metallogeny of the Paramillos de Uspallata Pb-Zn-Ag vein deposit in the Cuyo Rift Basin, Argentina

RUBINSTEIN NORA A.; CARRASQUERO SILVIA I.; GÓMEZ ANABEL L.R.; ANA PAULA ORELLANO RICHETTI; D' ANNUNZIO MARÍA CELESTE

COMPTES RENDUS GEOSCIENCE

ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER

Lugar: Paris; Año: 2018

1631-0713

The Paramillos de Uspallata Pb-Zn-Ag vein deposit, previously considered as a carbonate-base metal system genetically linked to a Miocene porphyry type deposit, is located in the Mesozoic Cuyo basin which was formed after the generalized extension linked to the collapse of the Permian orogene and the beginning of the Mesozoic Gondwana breaking up. Previous information along with new geological, mineralogical (microprobe analyses) and isotopic data (O, C and Pb) enable the outlining of a new descriptive model for this ore deposit. Based on stratigraphic and structural controls it could be considered of Middle to Late Triassic age and thus contemporaneous with the rifting and the subsequent distathermal sub-greenschist metamorphism. The mineralization resulted of an early Pb-Zn hydrothermal stage (sphalerite and galena with minor chalcopyrite and pyrite) followed by a Ag-Cu-Pb stage (freibergite-tetrahedrite with minor boulangerite and owyheeite) and a late barren stage. The ore fluids were of low temperature, low to moderate salinity and intermediate sulfidation and resulted from the mixing between metamorphic and meteoric fluids, with the lead sourced by the upper Paleozoic basement and the sulfur partly derived from a magmatic source. These characteristics enable to describe Paramillos de Uspallata deposit as silver-lead-zinc veins hosted in clastic sedimentary sequences genetically linked to the Cuyo rift basin and therefore redefining it as a detachment-related mineralization with a likely involvement of magmatic fluids in its genesis.