Structural and temporal relationships between volcanic activity, hydrothermal alteration, epithermal Ag–Pb–Zn mineralization and regional stress regime in the Quevar Volcanic Complex (Puna plateau, Salta Province, NW Argentina)

Abstract

In the Cenozoic Central Volcanic Zone of the Andes, the genetic relationships between regional deformation, volcanic activity, and epithermal mineralization are not fully established. In order to shed some light on the matter, we present new macro and mesoscopic structural data, fault-slip data inversion and 40Ar-39Ar geochronology for volcanic rocks, hydrothermally altered equivalents and epithermal Ag–Pb–Zn mineralization of the Quevar Volcanic Complex, which is located in the Puna plateau of NE Argentina. These data allow us to establish a first evolutionary stage with the eruption of the lavas and pyroclastic deposits of the Quevar Dacite in the Tortonian (9.9–8.7 Ma), when the volcanic activity was controlled by the NW-trending Calama-Olacapato-Toro lineament (COT). A second stage included the implantation of a hydrothermal alteration system and the related formation of the epithermal mineralization in the Messinian (7.7–6.3 Ma). These processes were contemporaneous with an ENE to E-directed shortening regime, which produced the reactivation of the COT and the formation of a left-lateral strike-slip stepover between WNW-trending regional faults. The third stage included the cessation of the hydrothermal activity and the erosion of the volcanic edifice. During this stage, mineralized veins and strike-slip faults were reactivated as normal faults by a NNW-directed extensional regime.