Document Type : Original Research Paper
Authors
1 Master of Science, Geological Survey of Iran, Tehran, Iran
2 Ph.D., Geological Survey of Iran, Tehran, Iran
3 Master of Science, Renewable Energy Organisation of Iran (SUNA), Geothermal Division
Abstract
Located in the NW Iran, in Sanadaj-Sirjan metamorphic belt, the studied area mainly comprises of metamorphic and varied acidic-basic igneous originated rocks. Basic metamorphic rocks have been chemically controlled by two main metamorphic processes including metasomatism and dynamic deformation. Amphibole and plagioclase are of the most significant minerals occurring in the rocks. Here we represent the chemical variations of those metamorphic minerals in relation to their host rocks and prograde metamorphism. Mineral chemistry analyses of amphibole minerals reveal an increase in Al2O3, TiO2 and a decrease in MgO, MnO during mylonitization of gabbroic rocks. Affected by metasomatism, the Al2O3 and Na2O contents of amphiboles have been also increased. CaO content of plagioclase has declined; in contrast, Al2O3 and Na2O have raised during mylonitization and metasomatism processes. These variations are overally ruled by chemical composition of the intruded pluton, pressure-temperature condition, oxygen fugacity and occurrence of equilibrant phases. Increasing Al and Na brings about tschermakite substitution in the deformed amphiboles and edinite substitution in the metasomatized rocks respectively.
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