Petrology of Granitoid in Mehman Area(SE Gharachaman-Eastern Azarbaijan
Mehman area is located in southeast of Gharahchaman in east Azarbaijan province. Granitoid rocks are intruded into Eocene volcanic rocks and have produced a weak contact metamorphism of epidotization, chloritization, kaolinitization and silisification. Limited exposure of marl and yellow to cream slightly crystallized limestone with plenty of coral and lamellibranchae fossils were observed (Qom formation), which cover the older sediments. Granitoids of the area are divided into two main groups, granitods of A group which contain predominant hornbelende and have high color index, granitoids of B group with less hornbelende and low color index. Field observations indicate that the emplacement of group B was before the emplacement of group A, which has produced plenty of silica veins in the eastern side of group B. In contact of A group rocks with B group intensive alteration has occurred. Granitods of B group have been formed due to differentiation of magmas producing A group granitoids. Petrographical, geochemical and field observations of these rocks show that they are KCG (K-rich and K-feldspar porphyritic calc-alkaline granitoids). A post collision tectonic environment is suggested for the rocks.