تحليل هندسي، جنبشي و مراحل دگرريختي سنگ هاي دگرگوني پيرامون مشهد

The Geometric, Kinematics and Deformation Stage Analysis of Metamorphic Rocks around Mashhad

The metamorphic rocks around Mashhad city were suffered by several stages of metamorphism and deformation. Special mineral and structural elements we re formed in these stages. Metamorphic grade in the pellitic rocks changes from green schist to amphibole facies. Foliations generally are steep toward northeast. Lineations predominantly have gentel to moderate plunge (less than 30°) toward northwest. Kinematic analysis of ductile structures in outcrop and microscopic scale shows dextral strike slip shearing with reverse component from northwest to southeast in shear zones. Contrasting of kinematic analysis of mesoscopic folds coeval deformation with shear sense obtained from ductile shear zones indicates the strain partitioning in the area. Based on field analysis and microscopic studies, the rocks were deformed by two stages of ductile deformation and followed by brittle-ductile and brittle deformation in later stages. The first and second stages of deformation occurred in a progressive and continuous manner accompanied by the higher grade of metamorphism in the area. The main stage of metamorphism is contemporaneous with early Cimmerian orogenic phase.