steady state deformation in the shear zones of the Sanandaj-Sirjan metamorphic belt, Neyriz region

Kinematic and structural studies on the deformed rocks of the Sanandaj-Sirjan metamorphic belt as a part of the Zagros Orogeny show that the deformation was occurred under greenschist- to amphibolite-facies conditions. A dominant top-to-the-SE sense of shear is confirmed by asymmetric boudins, mica fish, mantled porphyroclasts, drag folds, asymmetric crenulation cleavage and quartz c-axis fabrics.  The mean kinematic vorticity number analyses based on the quartz fabrics and rotated porphyroclasts revealed relative contribution of ~44% pure shear and ~56% simple shear components during ductile general shear deformation associated with a transpressional flow regime. The variable quantities of simple shear relative to time reveals that the earlier phases of deformation developed during a pure shear-dominated regime whereas the later stages took place in a simple shear-dominated regime.