Depósitos epitermales de baja sulfuración ricos en sulfuros de metales base, distrito aurífero La Carolina, San Luis, Argentina

la carolina gold-bearing district is located at the western end of the metallogenetic belt of san luis, which is spatially and genetically related to the mesosilicic volcanism of mio-pliocene age. the volcanic arc experienced an eastward migration, due to the flattening of the nazca plate in the segment 27°-33°s, known as the pampean flat-slab. at la carolina, the volcanic activity occurred between 8.2 and 6.3 ma. it encompasses lavas and pyroclastics of andesitic, dacitic, latitic and trachytic composition. the mesosilicic magmas belong to normal to high-k calc-alkaline and shoshonitic suites. structural analysis shows that previous structures have strongly controlled the emplacement of volcanic rocks and related mineral deposits at la carolina allowing to define a pull-apart. in this gold-bearing district there are eigth small mineralized prospects. the mineralogy consists of pyrite, arsenic rich pyrite, galena, sphalerite, marcasite, melnikovite, chalcopyrite, pyrrhotite, arsenopyrite, tennantite-tetrahedrite, digenite, covellite, bornite, pyrargiryte, hessite, silvanite, pearceite, argirodite, gold, silver, greigite, boulangerite, jamesonite and electrum. the gangue consists of quartz, calcite, chalcedony and minor adularia. the hydrothermal alteration is widespread and comprise phyllic and argillic mineral assemblages characterized by sericite, illite, interstratified i/s, and silicic; propylitic alteration is also present as an outer halo. fluid inclusions studies show that the formation temperatures range between 230o to 330o c. boiling and mixing with meteoric water led to mineral precipitation. based on the mineralogy, textures, hydrothermal alteration, formation temperatures, fluid chemistry and prospective geochemistry the mineralizations have been classified as low-sulfidation epithermal base-metal sulfide-rich deposits.