PETROLOGY, MINERALOGY AND GEOCHEMISTRY OF ALKALINE GRANITOID ROCKS FROM THE MISBOW MOUNTAIN (NORTH-WEST IRAN)

Pirmohammadi F.*, Amery A.**, Jahangiri A.**, Modjtahedy M.**

*Geological Department, Faculty of science, University of Tabriz, Iran, petrofarhad@yahoo.com

**Geology Department, Faculty of science, University of Tabriz, Iran

Abstract

The study area is located in NW of Iran, 20 km NW of Shabestar town. Geologically, this area is a part of western Alborz-Azarbaigaan zone. The rock types of this intrusion are alkali-granites and granites. Petrographical studies indicate that the texture of rocks is granular and the main mineral is perthitic orthoclase. Extensive existence of perthite shows that water pressure in magma was low.

The studied granitoid intrusion was embedded into the Kahar and Permian formations, and it caused contact metamorphism. Extensive existence of granophyric texture in some part of intrusion shows that the intrusion has embedded at shallow depth. The studied granite has the within plate origin with characteristics of A-Type granites emplaced in an extensive tectonic setting related to continental rift.

Petrological studies indicate the pressure of 2 kbar and temperature 830-870 °C in the intrusion. This study confirms the partial melting of lower crust sources with tonalite-granodiorite composition for this intrusion. But because of insufficient data, we can not estimate the partial melting of mantle source.

Key words: Shabestar, A-type granite, Cretaceous, oligo-miocene, alkaline

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