Deformation thermometry based on quartz and feldspar microstrucutres in the Seh-Ghalatoun metamorphic complex, Sanandaj-Sirjan metamorphic belt, Iran

 
In recent years have seen an increasing interest in the study of deformation characteristics like temperature in the orogenic belt. In this research, deformation temperature in the Seh-Ghalatoun metamorphic complex was estimated by using petrofabrics indicators such as quartz and feldspar recrystalization regims, quartz c-axis pattern and opening angle. The Seh-Ghalatoun metamorphic complex as a part of the Sanandaj-Sirjan metamorphic belt located in the east of Neyriz from the Fars province. Petrographic study and quartz c-axis measurements from the oriented samples of this area show that c-axis maxima concentrate in intermediate positions between the Y- and Z-axes of the finite strain ellipsoid. Also grain boundary migration and subgrain rotation recystallizations are dominant. Intermediate temperatures (400–500°C) are suggested by sub-grain rotation recrystallization microstructures (SGR) and high temperatures (>550 °C) can be inferred from grain-boundary migration (GBM) recrystallization microstructures. GBM microstructures were overprinted by partial grain-boundary migration (BLG), elongate new grains, feldspars book-shelf structures and micafish indicate two phase of deformation which earlier stage occurred on the lower temperature. Opening angles of quartz c-axis fabrics have ranging from 68° to 80° which is confirm deformation temperature between 490 and 610±50 °C. A positive correlation exists between deformation temperature yielded from quartz opening angle, active slip systems and microstructures. These results highlight greenschist-to-amphibolite-facies deformation conditions.