Mineral chemistry, thermobarometry and genesis of clinopyroxenes in Silurian mafic metavolcanic rocks of Maku, North West of Iran

There are discontinuous outcrops of volcanic rocks in the West Azarbaijan province and in the north of Maku city. These volcanic complex were bimodal and compose of acidic and basic lava and pyroclastic rocks. Mineral chemistry studies show that clinopyroxenes in the studied rocks are diopside. These pyroxenes have a high magnesium number (0.87 to 0.99). Magma series and tectonic determination diagrams show that the basaltic rocks that make up the studied clinopyroxenes have an alkaline nature and were formed in a whitin plate environment. According to geothermobarometry studies, clinopyroxenes were formed at temperature 1100 - 1250 ° C and pressure of 3 - 9 Kbar. The depth for generation of magma was at about 22 kilometers.