Mineral chemistry of the granitoid Ghalilan body (SW-Qorveh, Kurdistan) and its estimates of physicochemical parameters


همدان- خیابان شهید فهمیده- دانشگاه بوعلی سینا- گروه زمین شناسی


The Ghalilan granitoid pluton is located in SW- of Qorveh and in the Sanandaj-Sirjan zone. Based on petrographic studies, the body includes three rock units, composing of granitoid, porphyritic granite and diorite. These rocks are mainly composed of plagioclase, alkali-feldspar, quartz and amphibole. The composition of the studied plagioclase is An 14-50 (the minimum value in granite) to An 41.4-58 (the maximum value in diorite) and some samples display normal zoning and rapakivi texture. The results of electron microprobe analysis (EMPA) indicate the amphiboles studied are magnesio hornblende in composition implying I-type nature of magma. Application of different barometers and thermometers (e.g. Al-in-Hornblende, Plagioclase-Amphibole) exhibits a pressure of ~ 1 to 3.3 kbar and temperatures of 690-804°C for the intrusion. The reaction of these variations is reflected by the growth of minerals such as large zoned plagioclase crystals in the porphyrtic granites. In addition, the presence of the zoned plagioclase implies the PH2O variations at the time of crystallization and emplacement of the magma in the depth of ~8 km. The composition of hornblendes suggests their formation in high oxygen fugacity condition, which is in accordance with their mineralogical characteristics and tectonic setting of Ghalilan body (subduction in active continental margin).