An Investigation on the Mineralogy and Paragenetic Relationship of Buin Miandasht Skarn, Sanandaj-Sirjan Zone

The study area is located in north west of Isfahan and 25 km north west of Daran. Buin-Miandasht intrusive rocks consist of granite and granodiorite. Based on geochemical diagrams, these granitoids are calc-alkaline and evolved in volcanic arc environments. The studied rocks geochemically belong to the I -type granites. This intrusion has intruded into the metamorphic basement (Paleozoic?) and a small occurrence of skarn and hornfels has been formed. Based on field and petrographic investigation, two main stages of skarnization (progressive and regressive) have been identified. Progressive stage identified by anhydrous mineral assemblages (garnet, clinopyroxene). In retrograde stage, anhydrous silicates changed to hydrated calcic silicates (epidote, tremolite-actinolite, vesuvianite) and finally decarbonation reactions occured in response to CO2 increasing. This event led to the crystallization and replacement of calcite. Based on geochemical results, the composition of Buin-Miandasht granitoids are similar to granitoide composition associated with tungsten, molybdenum and tin mineralization worldwide.