Studies on fluid inclusions and stable isotopes (C, O and S) during generation and evolution of Khut copper skarn, West of Yazd, Central Iran

The Khut copper skarn deposit is located 50 km northwest of Taft city in Yazd province. Intrusion of granodiorite apophyses of Oligocene-Miocene age into upper Triassic carbonate units of the Nayband formation has led to the formation of skarn occurrences and sulfide marbles resulting in systematic depletions of 13C and 18O values in the calcite types. Based on the calculated models، isotopic depletion of calcites from less altered limestones to skarn zones can be attributed to the magmatic fluid infiltration. Skarn calcites show the most depletion compared to the other zones. These skarn calcites have been formed by magmatic fluids (δ18O =11. 0‰) that reacted/interacted with unaltered limestone rocks at temperatures of less than 600 oC with X (CO2) =0. 02 and water/rock ratio of 20 to 50%. The δ34S values of chalcopyrite separates from skarns and marbles from the Khut deposit indicate that there can be a dominant contribution of magmatic fluid that contains primitive mantle-dominated sulfur، such that δ34S values (δ34S of 1. 4 to 5. 2 ‰) in this deposit are similar to those of many notable porphyry Cu deposits and related Cu and Cu-Au skarns. Based on the microthermometric studies، salinity and temperature associated with formation of the Khut deposit، have been estimated 16. 3 wt. % NaCl equivalent and 400 oC، respectively.