نوع مقاله : مقاله پژوهشی
نویسندگان
1 خیابان دانشگاه نبش کوچه میلاد یک
2 گروه علوم زمین، دانشکده علوم طبیعی، دانشگاه تبریز، تبریز، ایران
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسندگان [English]
In this study, the chemical composition of amphiboles in Eocene andesitic rocks from northern Ardabil was investigated using electron microprobe analysis. The rocks have a porphyritic texture with plagioclase, amphibole (hornblende), and clinopyroxene phenocrysts. Disequilibrium textures such as reaction rims and sieve textures indicate rapid magma ascent and temperature-pressure changes. Analysis of 78 points from amphiboles showed that they are calcic with pargasite and magnesio-hastingsite compositions. Crystallization temperature was estimated at 843–928°C and pressure at 1.85–5.52 kbar (equivalent to a depth of 14 km). High oxygen fugacity and melt water content of 3.99–6.45 wt% were determined. The studied rocks formed in an active continental margin magmatic arc related to Neotethyan subduction. A mantle origin with limited crustal contribution and calc-alkaline affinity indicates partial melting of metasomatized lithospheric mantle due to fluids from the subducting slab.
کلیدواژهها [English]
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