Petrology and the effects of dynamic processes on the felsic rocks in the Darvazeh plutonic body (South Qorveh- Kurdistan)

• Main Authors: Ashraf Torkian, Tahereh Molaei Yeganeh, Ali Asghar Sepahi Gerow
• Format: Article
• Language: fas
• Published: University of Isfahan 2018-01-01
• Series: Petrology
• Subjects: felsic rocks; deformation; I-type granite; lower crust; continental arc margin; Qorveh; Sanandaj-Sirjan
• Online Access: http://ijp.ui.ac.ir/article_22396_772d1f0e9f06468d079043e286070f57.pdf

The Darvazeh pluton is located in the south of Qorveh. Olivine gabbro, diorite, quartz monzonite and granite rocks are rock forming of this body, but this paper is focused on the leucocratic to mesocratic rocks (quartz monzonitic and granitic rocks). These rocks were effected by dynamic tectonic activity during the intrusion and according to the distance of shear zone; deformation can be classified to cataclastic, protomylonite and mylonite. Microstructure evidences including the presence of porphyroclasts, bending of crystals and their twining, myrmekitic and pertite textures which caused by stress. Based on the microstructure features, deformations occurred at temperature of about 500-600 ° C. The geochemical data suggested that the felsic rocks belong to calc-alkaline, ferroan, I-type and metaluminous to slightly peraluminous series. Enrichment in LREE/HREE; negative anomalies of Ba, Ti, P, Sr, Nb and U, Th, Pb positive anomalies and Th/Ta ratios indicate continental arc setting. The presence of mafic enclaves, high volume of granite and negative trend of Zr versus SiO2, all suggest that the felsic rocks were generated via partial melting process. According to geochemical characteristics, the studied granitoid was originated by partial melting of meta basaltic rocks in the lower crust.