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Abstract

The syenogranitoid body of Almogholagh is located on the north of Asadabad. Despite of being young, it is positioned at collision contact of Zagros subduction zone. It is anomalous compositionally (high K and very high Na). On the basis of this study, it is indicated that the primary magmas were responsible for generating of this plutonic mass, are originated from a subducting oceanic crust under a continental crust at the end of the Laramid Orogeny phase, being emplaced and crystallized within the lower parts of the crust.
Later on, and in the presence of F and B fluids it is remelted and enriched of alkalies, particularly in sodium under the pressure of less than 5k bars (water vapour). Since waning slowly upwards pertitic textures were formed. Finally, under the effect of a sudden tectonic event a rapid uprising movement had taken place, which losing its water content were rapidly crystallized and granophyric textures being formed, where finally emplaced at the late Pliocene. Therefore, it is suggested that compositional anomalous of some subduction related igneous bodies of the crust in Iran [e.g. in Almogholagh) were formed as a result of remelting under the presence of F, B bearing active fluids.

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