Mica chemistry and metamorphism in garnet-micaschists of Haji-Qara high, North of Golpayegan

Garnet-micaschists from Haji Qara high, north of Golpayegan, are part of the metamorphic rocks of the Sanandaj-Sirjan Zone (SSZ). Lepidoporphyroblastic and porphyropoikiloblastic are the main textures and the mineral assemblages consist dominantly of Fe-biotite, muscovite and ferriphengite, metamorphic Fe-Mg chlorites (I-type and IIb), garnet and quartz. Staurolite, andalusite, plagioclase carbon, Fe-oxides and tourmaline are present as accessories. Petrographic evidences as well as mica chemistry along with other paragenesis and thermometric estimations indicate a path change from amphibolites facies to lower pressure and higher temperature gradient suggesting the presence of a local pluton which led to garnet porphyroblast, biotite and muscovite (overprinted in different orientation) and andalusite crystallization. The occurrence of chlorite, ferriphengite and Fe-oxides demonstrate a retrograde metamorphism during uplift and decompressional cooling path in the area.