Chemical composition of amphiboles in metamorphic rocks of ophiolitic complex of Eastern Birjand: confirming of pressure-temperature evolution of these rocks

Eastern Birjand ophiolitic complex consist of different rock types of a complete ophiolitic sequence. Three groups of amphiboles which exist in metabasites of this ophiolitic complex are of: calcic amphiboles, such as actinolite-tremolite and magnesio-hornblende; calcic-sodic amphiboles, e.g. vinchite and barroisite; and sodic-amphiboles, e.g., glaucophane, magnesio-riebeckite and ferro-glaucophane. Petrographic studies, geothermobarometry results and composition of minerals, especially amphiboles in mineral assemblage of different metamorphic rocks clearly indicate pressure-temperature variations of metabasites within different evolutionary stages. This indicates that subduction and subsequent thrusting are occurred in the studied area.