Abstarct: The study area is located in northwest of Qazvin, northeast of Loshan, in the western Alborz structural zone baxsed on the field and petrographical studies and chemical classification diagrams, lithological units of this district are composed of submarine pyroclastics (including tuff, lapilli tuff and epiclastic deposits), middle-upper Eocene lavas (including olivine basalt, trachyte, trachyandesite, andesite, rhyolite and dacite) and intrusive rocks belong to post-eocene, probably oligo-miocene (including olivine-gabbros, diorite and monzodiorite). Evidences of continuous changes in minerals, such as appearance and disappearance of some minerals, sieve texture, corrosion gulfs, burned rims in amphiboles and biotites and rounding of mineral margins could be observed in petrographical studies. These characteristics, along with sample trends in major, minor and trace elements variation diagrams, indicate that these rocks have been related by fractional crystallization. Dacitic and rhyolitic rocks, does not follow the patterns of the other volcanic rocks in chemical diagrams. However, these rocks have another origin, probably partial melting of continental crust due to injection of an high temperature basic magma into them. Geochemical features, along with trace elements, spider and discrimination diagrams, show an high-K calc-alkaline magmatic assemblage and a continental arc tectonomagmatic model of subduction zones for these rocks. The studied rocks have a composition, specially in La and Sm concentrations like melts derived from enriched mantle, and plots in the field of 10-20 percent partial melting of a garnet-spinel lherzolitic source in 90-110 km depths.