Mineralogical study and the effective processes on the volcanic rocks of the Jahagh Anticline (South of Kashan)

The Jahagh anticline is located at 40 km south of Kashan and east of Ghohrud village. The Early Paleozoic volcanic rocks are outcropped in the Jahagh anticline core. Despite low degree alteration and metamorphism that are identified by mineralogical studies, the primary textures are well preserved whereas mineralogical composition has changed. The major minerals including of plagioclases and rare Fe-Mg minerals have experienced alteration. The presence of secondary minerals such as albite, chlorite, epidote and calcite shows that the low-grade metamorphism have occurred under greenschist facies. Following the intrusion of Ghohrud granitoid, the adjacent volcanic rocks have been metamorphosed under hornblende - hornfels facies. This phenomenon is evidenced by the association of plagioclase (oligoclase - andesine) and amphibole (Ferro -Tschermakite) in the rocks of western parts (approaching the intrusive mass).