Metamorphic evolution and thermodynamic conditions Of Halab-Mianaj metamorphic crosse section based on mineral chemistry

Halab-Mianaj metamorphic area is part of Takab Precambrian metamorphic complex that exposed in north-west of Iran. Halab-Mianaj cross section included a group of metamorphic rocks that have been metamorphosed in the greenschist and amphibolite facies. Garnet porphyroblasts chemical composition in garnet schist rocks is in almandine range. Amphibole composition in Amphibole schist and meta-diorite rocks are calcic and are changed from actinolite to magnesio hornblende. Chemical compositions of the Plagioclase crystals are between albite to oligoclase range. The maximum temperature for garnet schist rocks based on Grt-Bt thermometer determined 552°C that indicates epidote-amphibolite facies. Temperature and pressure metamorphic in the amphibole schist and meta-diorite based on amph-plag thermobarometer determined about 420 - 487°C and 3.9 - 6.7 K-bar that shows the beginning amphibolite facies. Therefore, the geothermal gradient bases on Halab-Mianaj metamorphic rocks with different protolith approximately are 30 ± 1° C/km.