Mineral chemistry and geothermobarometry of the metapelites of Geysour metamorphic complex, east of Gonabad

Geysour area, east of Gonabad, is a part of the northern Lut block. The rocks in this area include granitoid and a series of metamorphic rocks. In metapelitic rocks, the presence of S1 schistosity and the mineral chloritoid are indicative of regional metamorphism. The presence of random textural evidence in minerals such as andalusite, staurolite, muscovite and post-tectonic garnet and silimanite growth within the andalusite margin is characteristic of contact metamorphic rocks. The mineral garnet has two stages of growth, and mainly contains the end-members of Almandine, Grossular and spessartine. Chloritoid and staurolite are ferrous. Muscovite has little paragonite replacement. Chloritization of biotite and garnet, sericitization of andalusite and the occurrence of radial micro-cracks in garnet all indicate a retrograde metamorphism and uplift. Based on conventional geothermobarometric methods, temperature and pressure were calculated in the range of 550-608 oC and 3.8-4.5 Kbar, respectively. The existence of radial micro-cracks around quartz inclusions in garnet is due to a large component of isothermal decompression.