摘要：Salafchegan-Khorhe volcanic rocks are exposed within Urumieh-Dokhtar magmatic belt. Differentkinds of volcanic and subvolcanic rocks of calc-alkaline to alkaline character have been reportedthroughout this magmatic belt. Since, isotopic investigations are very useful for detection of magmapetrogenesis and because no isotopic studies have been done in this area, so a geochemical andisotopic study was carried out for Salafchegan igneous rocks, Sw of Tehran, in order to constraintheir petrogenesis and confirm that parental magma in this area, is similar to calc-alkaline magmasrelated to continental margin arc environments.The igneous rocks dominantly consist of andesite,diorite, quartz-diorite, tonalite, dacite-rhyodacite and granodiorite porphyries with calc-alkalineaffinity. Harker diagram indicates that amphibole, biotite and plagioclase have played an importantrole during the crystallization of Salafchegan igneous rocks and proves the effect of fractionalcrystallization during magmatic evolution. These rocks are characterized by enrichment in light rareearth elements (LREE) and large ion lithophile elements (LILE) and depletion of HREE and HFSEand negative anomalies of Nb, Ti, Zr and P that indicated the formation of rocks in a subductionzone of active continental margin. The 87Sr/86Sr and 143Nd/144Nd isotopic ratios of the studied rocksare from 0.705201 to 0.707187 and 0.512508 to 0.512646 respectively. All of these samples arecharacterized by negative εNd values which can show the role of crustal contamination in theirpetrogenesis and also suggest the enrichment of the lithospheric mantle beneath this orogenic belt.The geochemical and Nd-Sr isotopic data demonstrate that fractional crystallization andassimilation have played an important role in magmatic evolution of this region.
