Carbon-oxygen isotopic covariation of the Changarzeh Pb±Ag deposit (south Natanz): implication on fluid/rock interaction and CO2 degassing processes

Study of carbon-oxygen isotopic variations in the gangue carbonate minerals and related host rocks has an important role in identifying carbonate hosted lead and zinc deposits and its mechanism of sulfide ore formation. The yellow color dolostone unit attributed to the Shotori Formation with the Middle Triassic age is the main host of sulfide mineralization which deposited on the shale horizon attributed to the Sorkh-Kuh Formation. Galena, sphalerite, pyrite and silver-bearing sulfosalts are the most important sulfide ore minerals in the area, which were formed accompanied with the first (Cal-1) and second (Cal-2) generation calcites. Based on the results of carbon-oxygen isotope data, δ13C and δ18O values in Cal-1 varies from -3.2 to -0.7 ‰ and 12.9 to 14.6 ‰, respectively; and δ13C and δ18O values in Cal-2 varies from -7.3 to -4.4 ‰ and 13.7 to 16.4 ‰, respectively. The carbon-oxygen isotopic composition in the dolostone host rock with compared to calcites has a higher δ13C content (varies between -3.2 to 2.9 ‰) and a wider δ18O range (varies between 22.6 to 28.8 ‰).