مقایسه انواع آمفیبول‌ها و ژئوترموبارومتری توده نفوذی آستانه (زون سنندج- سیرجان)

The results of microprobe analysis indicate four different kinds of amphiboles in Astaneh pluton and its subvolcanic rocks in the Sanandaj-Sirjan zone. The composition of these amphiboles in this area are magnesio hornblende in tonalite and quartz dioritic enclaves, actinolite in granodiorite and monzogranite, pargasite in dacititc enclaves and anthophillite in one tonalitic sample formed by replacement of orthopyroxene at the rim. All of the amphiboles crystallized at high fO2 which imply I-type nature. Application of different barometers and thermometers show that pargasite in dacitic enclave formed at higher pressure and temperature (767 °C, 6.6 Kbar) than the magnesio hornblende in quartz dioritic enclave (734°C, 2.8 Kbar) and magnesio hornblende in tonalites (708°C, 1.4 Kbar).