Ore structural, textural, mineralogical and fluid inclusions studies of the Kouh-Kolangeh Zn-Pb-Ba deposit, Malayer- Isfahan metallogenic belt, South Arak, Iran

The Kouh-Kolangeh carbonate-hosted Zn-Pb-Ba deposit is hosted by Lower Cretaceous detrital-carbonate sequence in the central part of the Malayer-Isfahan metallogenic belt (MEMB) and has been formed within an extensional basin. Ore mineralization occurred as concordant with layering in the upper part of non- argillic massive orbitolina gray limestone (Kl) and at the boundary of shale- marl with intercalated thin bedded limestone unit (Ks) with Aptian age. Sulfide minerals include sphalerite, galena and pyrite. Barite is the most abundant non-sulfide mineral associated with quartz, calcite and dolomite. Ore textures and structures include breccia, replacement, vein-veinlets, massive barite and laminated ore. Silicification and carbonatation (calcification- dolomitization) are the main wall-rock alterations. Based on fluid inclusion studies, fluid inclusions can be divided into two types: (I) two-phase fluid inclusions (T1) with amoebic and irregular shapes and average homogenization temperature of (T1) 206.8°C and the average salinity of 8.3 wt% NaCl. (II) CO2-rich three-phase fluid inclusions (LCO2-LH2O-VCO2) (T II) with spherical shapes and average total homogenization temperature of (T1) 234.8°C and the average salinity of 7.17 wt% NaCl. According to evidence such as tectonic setting, type of host rock, layered geometry of deposit, ore textures and structures, homogenization temperature, average salinity and presence of massive barite, the Kouh Kolangeh deposit can be considered as an Irish-type Zn- Pb deposit .