Study of clinopyroxene in Eocene volcanic rocks of the Choupanan area (Central Iran, NE of Isfahan)

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Abstract

Volcanic rocks of the Chuopanan area are a part of the Yazd block (central Iran) and they include lava and pyroclastic rocks. These rocks belong to the Eocene and predominate volcanic rocks in this area are andesite that represent the NE-SW trend along the fault. pyroxene is the most significant mafic mineral of these rocks. These are as partly altered phenocrysts. Chemical compositions of clinopyroxene in these rocks range from diopside to augite. The mineral chemistry of clinopyroxene and field relationship and petrography evidence indicate that the composition of magma forming have the calc-alkaline affinity and belong to volcanic arc field. Aluminium supplies in octahedral and tetrahedral positions shows that the mineral was crystallized in low pressure in hydrous magma. Ferric Iron is related to the high oxygen fugacity content environment. 

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