[Petrology of Mafic Rock Series in Northeastern of Hashtjin, South of Ardabil, Iran]

Mafic rocks in NE of Hashtjin area are composed of basalts, spillite, olivine basalts, andesitic basalts, andesites, dacites, pyroclastic rocks and numerous doleritic dikes cutting all these rock units. In this area, basalts have calc-alkaline and within plate affinity. These basalts have high content of LIL, LREE and HFS elements. Titano-magnetite grains in mafic rocks are divided into Ti-rich varieties and less Ti-rich types (rich in Fe+3). Plagioclases show normal zoning and their phenocrysts have high An content compared to the plagioclase microlites. Salite composition and the high content of Al, Fe and Ti are the main characteristics of Pyroxenes. The enrichment of mafic rocks in incompatible elements, calc-alkaline and within plate nature as well as high Al content of basalts, enrichment of pyroxenes in Al, Ti and Fe, could be all an indication to suppose the implication of a continental arc for the genesis of these rocks.