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The study of dual entity of alkaline – calcalkaline magma origin in plutonic rocks in Aftabrou area, North West of Saveh, Arak – JBES

Akram Sabzian, Fariborz Masoudi, Hoshang Asadi Harooni, Mohammad Hashem Emami, Nima Nezafaty

Department of Geology, Science and Research Branch, Islamic Azad University (IAU), Teheran, Iran

Faculty of Earth Sciences, Shahid Beheshti University, Evin, Tehran

Department of Mining Engineering, Isfahan University of Technology, Isfahan, Iran

Department of Geology, Science and Research Branch, Islamic Azad University, Eslamshahr (Tehran), Iran

Key words: North West of Saveh, Aftabrou, Calc-alkaline, Alkaline.

Abstract

Aftabrou plutonic rocks outcropped in 70 km North West of Saveh and are in Orumiyeh-Dokhtar volcanic zone, which have plutonic to sub plutonic rocks with after post Eocene age and including with older volcanic rocks (Middle to late Eocene). Plutonic rocks consist of granodiorite and have minerals such as plagioclase (albite- andesine), alkaline feldspar (orthoclase), amphibole (hornblende) and quartz with granular texture and sometimes poikilitic and graphics textures. Sub plutonic rocks consist ofdiotite and have minerals such as plagioclase (andesine- labradorite) amphibole (hornblende) and sometimes, quartz with porfiroid, intergranular texture. To determine tectonic setting, petrogenesis and magma series was used the results of geochemical analysis (XRF and ICPMS) for draw geochemical diagrams. Tectonomagmatic graphs show both magmas are related to subduction zone in active continental margin. Low frequency of Ti, Sr, P elements and positive anomalies of K, Rb, Ba, Th, La, U elements in the spider diagrams patterns that normalized by chondrite and primitive mantle shows that origin of plutonic rocks are molten with crustal protolith and crystallization of it. Sub plutonic rocks are result of asthenosphere molten, So that in subduction zone, reduce pressure and subducted fracture wedge cause to go out asthenosphere melt near the rift and make alkaline magma.

Get the original articles in Source: Volume 6, Number 6, June 2015 – JBES

Journal Name: Journal of Biodiversity and Environmental Sciences (JBES)

Published By: International Network for Natural Sciences

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