Petrology and petrography of quaternary volcanic rocks of north-northeastern Varzaghan (eastern Azarbaijan)
Subject Areas :پروین Hajizadeh 1 , M.H Emami 2
1 - دانشجوی کارشناسی ارشد زمین شناسی، دانشگاه آزاد اسلامی، واحد علوم و تحقیقات، تهران
2 - عضو هیئت علمی دانشگاه آزاد اسلامی، واحد اسلامشهر
Keywords: Varzaghan, basalt, Andesite, crustal contamination, intercontinental basalt,
Abstract :
The studied area is located in the north-northeastern of Varzaghan in Eastern-Azarbaijan province, andfrom the structural point of view in Alborz-Azarbaijan Zone. In this area the Quaternary volcanicrocks are extended over the Pliocene units. The volcanic rocks under study are basalt, trachybasalt,trachyandesite and basaltic trachyandesite. These rocks have porphyritic texture with microlitic matrixand their main minerals consist of pyroxene and plagioclase.On the basis of geochemistry studies the volcanic rocks in this area have alkaline nature with sodictendency and are enriched in light rare earth elements (LREE) and depleted in heavy rare earthelements (HREE). Petrographic and geochemistry evidences show the effect of mantle partial melting,fractional crystallization, contamination and continental crustal anatexy phenomena in formation ofvolcanic rocks. According to geotectonic diagrams these volcanic rocks belong to intercontinentalbasalts.