Mineral chemistry and thermobarometry of East Salmas metamorphic complex, northwestern Iran

East Salmas Metabasites, as one of the most extensive units of the metamorphic complex, is located in the northwest of Sanandaj-Sirjan zone. These metabasites are mainly composed of amphibolite and green shist, alternating with geniss, metadiorite and marble metamorphic rocks. Metabasites are structurally oriented and mass, and grain size varies from small to medium. According to microscopic studies, the regionchr('39')s metabasites are classified into 6 amphibolitic and 4 schist subgroups. Amphibole, plagioclase, mica, spinel, and quartz are the main minerals from the microprobe results of metabasite samples. According to the chemistry of minerals, amphiboles are composed of magnesium hornblende and ferrotschermakite, plagioclase with component of andesine, mica with type of phlogopite and spinel groups with component of Al-spinel. Chemical composition of amphibole and plagioclase minerals was used for themometry and barometry of metabasite rocks in the region. Thereforet the results show that regional metamorphic rocks are formed in moderate temperature (550-600 ° C) and pressure (4-6 kbar) ranges, Barrovian-type amphibolite facies, 30 ° C / Km geothermal gradient and in the intra-continental orogenic environments.