نوع مقاله : مقاله پژوهشی
نویسندگان
گروه زمین شناسی، دانشکده علوم، دانشگاه تربیت مدرس، تهران، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
The studied area is located in the northwest of Iran, south of Ardabil Province, in the Alborz-Azerbaijan zone. The important volcanic phases in the region, based on K-Ar dating, include three sequences: Eocene (trachyandesite), Oligocene (basalt, basaltic andesite) and Miocene phase (basaltic andesite, basaltic trachyandesite and rhyolite). The Eocene sequence shows the nature of shoshonite and the Oligocene and Miocene sequences show the nature of calc-alkaline to calc-alkaline perpotassium. All three sequences in multi-element diagrams normalized to the primary mantle show negative Nb-Ti-Ta anolalies, depletion in Y,Yb,Ti and enrichment in Rb,Ba,K,Th. Most likely, the slab break-off of the Neotethys subducting plate, as a result of the creation of an asthenospheric window in facilitating the partial melting process, has caused the partial melting of the metasomatized continental lithospheric mantle and the formation of the Eocene-Oligocene volcanic sequence. The source of heat for Miocene-Quaternary volcanoes is also related to the rise of the asthenosphere, which is caused by the delamination of the lithosphere. Using this study, we improve our understanding of the nature, origin and magmatic evolution of the igneous rocks of northwestern Iran, which are influenced by geodynamic environments.
کلیدواژهها [English]