Study and Comparison of Miocene-Quaternary Volcanoes In NW of Iran, Lesser Caucasus and SE of Anatolia: Geochemistry, Source and Tectonic Setting

The Late Miocene- Quaternary volcanoes including Sahand, Ararat, Nemrut, Suphan, Tendurek and Lesser Caucasus volcanoes in the Arabia-Eurasia collision zone, are studied in this paper. The volcanoes have been erupted pyroclastic materials and lava flows with basaltic to rhyolitic composition, in several times. These volcanic rocks have calk-Alkaline (Sahand) to Alkaline nature (Tendurek). The Nb, Ta, Ti and Y depletions in accompanied with Rb, Ba, K, Sr and Th enrichments are the common geochemical features of these volcanic rocks in primitive mantle normalized multi element diagrams. In addition, enrichment of LREE relative to HREE in chondrite–normalized REE patterns is visible in all volcanic rocks of the regions. The enrichment of LREE and depletion of HREE in Sahand and Lesser Caucasus volcanic rocks is implying that their magma is derived from fraction melting of garnet-lherzolite of mantle source. In contrast, the volcanoes of eastern Anatolia melted from spinel-lherzolite rocks of mantle. The negative Nb, Ta anomalies in primitive mantle normalized multi element diagrams of volcanic rocks indicate geochemical features of Pre-collision subduction component in parental magma of studied volcanoes. High contents of La, Th, Ce and Rb indicate magma contamination during parental magma emplacement in crust accompanied with assimilation, fractional crystallization process.