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

The study area is located in northwest of Isfahan, 25 km northwest of Daran. Buin-Miandasht intrusive rocks consist of granite and granodiorite. Based on geochemical diagrams, these granitoids are I -type calc-alkaline and evolved in volcanic arc environments. The Buin-Miandasht intruded into the metamorphic basement (Paleozoic?) and a small skarn and hornfels occurred along its contact. 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 occurred in response to CO2 increases, which led to the crystallization and replacement of calcite. Based on geochemical results, the composition of Buin-Miandasht granitoids are similar to granitoide associated with the tungsten, molybdenum and tin mineralization worldwide.