Geothermometry of deformation in the marbles based on the twinning in the northeastern of Jan Mine, Sanandaj-Sirjan Zone, Lorestan Province

The study area is a part of Sanandaj- Sirjan Zone that is located in the northeastern of the dimension stone of Jan mine in north of Doroud city on Lorestan Province. It is mainly composed of deformed metamorphic rocks including deformed marbles associated with mylonitic gneiss- granite and amphibolite. The main texture of the marbles is lepidogranoblastic and their mineralogical composition are calcite, quartz, phengitic muscovite, epidote, sphene, opaque minerals and minor plagioclase. Calcite grains have preferred orientation, which show strain and crystal-plastic deformation. The formation of flayser texture in the quartz lenses, undulatory extinction in the quartz grains, existence of pining microstructures, dynamic recrystallization as grains boundary migration (GBM) between calcite and quartz, bulging recrystallization (BLG) in the quartz grain boundaries along fracture planes, Subgrain Rotation (SGR) and also, deformation twinning in calcite crystals show the temperature of deformation ranges from 150 to 300 °C for the marbles.