The geology and 40Ar/39Ar geochronology of magmatic activity and related mineralization in the Nevados del Famatina mining district, La Rioja province, Argentina

摘要: The Nevados del Famatina mining district (NFMD) is located in La Rioja province, Argentina. This contains porphyry-style mineralization (Nevados Famatina) and high sulfidation veins (La Mejicana). stratigraphic column the NFMD begins with Cambrian siltstones which were metamorphosed during Late Ordovician - Early Silurian intruded by Ordovician-Silurian granitic rocks. These units covered Upper Paleozoic Tertiary continental sedimentary rocks are intercalated overlain dacitic-rhyodacitic porphyritic (Mogote Formation) emplaced Pliocene. All these Pleistocene sediments Quaternary alluvial colluvial deposits. Magmatic activity related have been dated 40Ar/39Ar technique. Step heating studies of orthoclase biotite phenocrysts from Mogote Formation suggest that igneous around 5.0±0.3 Ma ago. However, plateau ages outer carapace subjacent granodioritic magma chamber muscovite quartz-sericite alteration at both Mejicana 3.8±0.2 Ma. Emplacement shallow stocks separated cooling to temperatures below 350° C a time span approximately 1 During this interval, convective hydrothermal system was established proximal chamber, resulted porphyry molybdenumcoppergold adjacent more distal fault zones.