Mineralogy andgeochemistry of analcime bearing alkaline rocks in Salavat range, Azerbaijan Magmatic Plateau, NW Iran


Department of Geology, Faculty of Earth Sciences, Shahid Beheshti University, Tehran, Iran


The Alborz-Azerbaijan magmatic plateau (AAMP), in the northwestern part of Iran, is one of the main exposes of magmatic activities in the Cenozoic. The Salavat range is located in the eastern part of AAMP, and widely occur in alkaline lavas and dykes Based on field studies, mineral chemistry, and whole-rock geochemistry, alkaline rocks in the Salavat range are classified into two groupsthat are composed of analcimite, analcime bearing breccias and analcime bearing tephrite pillow lavas (group I), tephrite-phonotephrite and lamprophyre dykes (group II). These rocks cover a broad compositional range from sodic to transitional sodic-potassic and potassic series, all of which are high-K in character. On the basis of whole-rock chemistry, alkaline rocks in the Salavat range resulted from a phologopite/amphibole-bearing peridotite source in garnet-spinel lherzolite transitional zone that underwent metasomatism processes. Geochemical data indicated partial melting of subcontinental lithospheric mantle source, played major roles in the formation and evolution of the Salavat range rocks, whereas crustal contamination seems to be restricted to minor effect. The Salavat range magma was generated in a collision-related extensional setting, following the closure of the Neotethys Ocean in the Cenozoic.