Evidence of the Effect of Metasomatism and Introduction Tourmalinite Veins in the Almabulage complex (NW Iran)

Almabulage complex is located in the north of Asadabad city, northwestern Hamedan province, in Sanandaj-Sirjan structural zone. The complex includes several types of low-grade metamorphosed rocks with various protoliths as well as two intrusion having different chemical compositions of synogranite and gabbro. The synogranite intrusion rock has perthite and granophyric co-growths textures and automorph Titanite, along with veins of tourmalinite around it. Given the chemical composition of tourmaline mineral, presence of tourmalinite in several environments is attributed to the presence of boron-content fluids. In the present article, the relationship existing between chemical composition of minerals and metasomatism in the synogranite rock of Almabulage complex has been studied. Tourmaline minerals in tourmalinite veins have radial accumulation as well as zoning. Chemical composition of tourmaline mineral has been analyzed using the Electron Micro Probe Apparatus, EPMA, at the University Japanese Naruto. Lack of any defect in the position of X, low value of Al, relative frequency of Mg, Ca, and chemical zoning are all indications of formation of tourmalinite veins in hydrothermal environments. Furthermore, presence of sodic minerals and the obvious anomaly of Na in plagioclases, which makes those plagioclases having zoning to be appeared as rich in Albite, as well as formation of metal minerals of magnetite type in this complex all may be considered as evidence of the effect of alkaline metasomatism in Almabulage complex.