Petrography and mineral chemistry of basaltic prisms of south Germi city (South talesh)

The study area is located in 9 km south of Germi city and 52 km north of Ardabil Province. From Structurally point of view this area is a part of south Talesh Zone. The volcanic rocks are mostly basaltic in composition with prismatic structure. Minerals of olivine, plagioclase, clinopyroxene and minor minerals such as titanomagnetite are formed the rocks. By the way calcite, sericite and chlorite with a lesser amount of idengsite are secondary minerals. Investigates show that phenocrysts of feldspar are mostly labradorite in composition and clinopyroxenes in studied rocks located in augite domain. Clinopyroxenes and olivines are originated from alkaline magma that belong to back-arc- basin magmatism. Thermobarometry of clinopiroxenes show that these minerals are crystallized from magma at ~5 Kbar pressure and 1000 C. Chlorite as a secondary mineral in these rocks generally are located in diabanit domain.and from geochemically point of view and zonation including two alteration stages that indicator of variety of factors in produce of secondary minerals.