Mineral Chemistry and Thermodynamic Conditions of Darreh Sary Metapelites, South East of Aligudarz, Sanandaj- Sirjan Zone

The study area is located in the northern part of the Sanandaj-Sirjan structural zone, between Daran and Aligudarz towns, near Darreh Sary village. Based on field and petrographical evidences, exposed metaplitic metamorphic rocks in this region, consist of five categories: phyllites, slates, muscovite biotite schists, garnet schists and staurolite schists. Mineral chemistry compositions of the metaplites are from garnets that are rich in almandine, plagioclases are mostly rich of albite, black micas are annite and siderophyllite, white micas are almost in the end member of muscovite and chlorites are ripidolite. Reactions that took place in these rocks, have caused the reduction of chlorite and muscovite and have led to the formation of some minerals such as biotite, garnet and staurolite in metamorphism progress. The chemical composition of the minerals such as garnet shows progressive metamorphism with homogenization of these minerals. Presence of secondary chlorites in these rocks exhibit uplift and retrograde metamorphism up to greenschist facies. Thermodynamic study of the mineral chemistry of mineral such as garnet, biotite, muscovite and chlorite suggests thermic peak of 630°C and pressure peak of 6.5 kbar. Thermobarometric data reveal barovian metamorphism type or orogenic trend with the passing of greenschist to middle amphibolite facies.