نوع مقاله : مقاله پژوهشی
نویسنده
دانشگاه پیام نور، تهران، ایران.
چکیده
کلیدواژهها
عنوان مقاله [English]
نویسنده [English]
Eocene volcanic rocks of AmirKandi, northern Ardabil, represent part of the Cenozoic magmatism of the Alborz–Azerbaijan zone, NW Iran. Petrography, mineral chemistry, and whole-rock geochemistry were integrated to constrain magma crystallization, source, and evolution. The volcanic suite comprises trachyte, trachyandesite, and basaltic andesite, characterized mainly by porphyritic and trachytic textures. Amphiboles are calcic and predominantly magnesio-hornblende, whereas alkali feldspars range from sanidine to anorthoclase. Amphibole thermobarometry indicates crystallization at ~710–810 °C and 1–2.6 kbar, corresponding to shallow crustal depths of ~4–10 km. The rocks display high-K calc-alkaline to shoshonitic and predominantly metaluminous affinities. LREE–LILE enrichment coupled with negative Nb–Ta–Ti anomalies indicates partial melting of a metasomatized lithospheric mantle that retained the geochemical imprint of earlier subduction. Magmatic differentiation was dominated by fractional crystallization with limited crustal assimilation, consistent with a post-collisional tectonomagmatic setting.
کلیدواژهها [English]
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