Geological, fluid inclusion and isotopic characteristics of the Gardaneshir Zn–Pb deposit, Central Iran

The Gardaneshir Pb–Zn deposit is hosted by dolomitic carbonate of the Shotori formation which is located in the SW Ardestan in Isfahan province. Ore body in this deposit is dominated by stratabound type. Primary ores in this type are composed of sphalerite, galena, barite and quartz with massive, banded, veined and disseminated structures. Evaluation of ore-grade at Gardaneshir Pb-Zn deposit, based on chemical analysis indicates average values of 4.35% Pb, 0.17% Zn, 20 ppm Ag in the form of galena, sphalerite, minor cerussite and smithsonite occurred along brecciated and silicified fractures mainly by NW-SE trending. Physico-chemical information of ore-solutions under chemical control, performed by entrapped fluid inclusion studies in gangue minerals. Through this way, liquid-rich two phase (L+V) inclusions as predominant types were recognized. These types of inclusions are homogenized into liquid state with a range of TH and related salinities ranges: 78-183 and 216-283 °C, respectively. Salinity ranges vary 3.5-5.86 and 9.7-25 wt% NaCl eq. The above microthermometric data reflect the nature of two populations of fluid inclusions originating from different source. The source materials would have provided by basinal brines, derived during compaction of sediments in shallow sea environment and then by upward movement into sediments, the stratabound dolomitized carbonate hosted Pb-Zn deposit will be formed. Furthermore; the range δ34S from -0.6 ‰ to -20.4‰ that have been extracted by galena can be an evidence of bacterial sulfate reduction in a subsidence sedimentary basin. This study suggests that the Gardeneshir Pb–Zn deposit is an epigenetic, thrust foldcontrolled and stratabound deposit with fluids and metals derived from the Triassic sedimentary strata.