Application of calcite twins for thermometry of carbonate mylonite in Qatruyeh metamorphic complex (NE of Neyriz)
Subject Areas :
Keywords: Sanandaj-Sirjan Carbonate mylonites Twins Qatruyeh metamorphic complex ,
Abstract :
Qatruyeh metamorphic complex in SW of Iran is located in NE of Nayriz in eastern border of the Sanandaj-Sirjan metamorphic zone. The complex consists of different schists, carbonate metamorphic rocks, quartzite, metasandstone and metavolcanics. Zagros fault movements appear as north-south Qatruyeh-Darehbid fault in the western part of the complex and is composed of a shear zone with carbonate mylonites as a main rock unit. In this research, the shear zone introduced and thermometry of deformation estimated based on twins of calcite in carbonate mylonites. Microstructure studies, based on morphology and twin width of the calcite crystals, show crystal- plastic deformation in calcite, which formed mostly mechanical e-twinning. The width of the calcite twins in studied samples range between 0.5-15 microns with density of 10 to 55 twins in millimeter. Based on experimental and mineralogical studies, temperature of the deformation estimated between 250 to 300 ˚C. Paragenesis of minerals in schists show that metamorphism developed up to green schist to lower amphibolite facies and followed by dextral sense of main faults of the area as dynamic metamorphism.