Petrology of the Tekyeh-Bala area granite veins (northeast of Sonqor), some evidences for A2-type granitoids

Magmatic activities during Mesozoic and Cenozoic emplaced several basic, intermediate and acidic intrusive bodies in the north part of the Sanandaj-Sirjan zone. Most of these bodies have genetic relationship with each other, but some of them formed by special magmatic processes and show different geochemical features. In the Tekyeh-Bala area (northeast of Sonqor) there are several granite veins which penetrated into the diorite rocks and have different geochemical characteristics from the host diorite. These granitic veins are alkalic belonging to the shoshonitic magma series. Also, they possess the geochemical properties of A-type granitiods, i.e., metaluminous nature (A/CNK=0.96-0.99), high HFSE (HFSE=192-412 ppm), Zr (230-420 ppm), FeOt/(FeOt+MgO) (0.89 in average) and K2O (4.2-6.2 wt%) contents. Regarding to the relatively enrichment of Rb, K, Cs and Th with respect to Nb and Ti in these samples which is a indicator property of active continental margins and also their post-orogenic tectonic regime, the studied granite can be classified as A2-type granitiods.