GEOCHEMICAL EVIDENCES TO INDICATE GENESIS OF INTRUSIVE BODIES OF NADUSHAN IN CENTRAL OF URUMIEH- DOKHTAR MAGMATIC BELT, IRAN

In south west of Nadushan an intrusive complex of Oligo- Miocene age, belonging to Urumieh- Dokhtar magmatic belt is out croped. This magmatic belt consists of large volumes of Eocene volcanics and Oligo- Miocene plutonic rocks. In this study it is tried to find out the missing ring from Urumieh-Dokhtar magmatism, by indicating genesis of Nadushan intrusive complex. This intrusive complex has seven small granitoidic bodies which could be divided into four suites based on field relations, emplacing time, mineralogical, textural and chemical characteristics. Diorites are the oldest suite while Leucogranite and granites are the second and the third suites, that Granites are crossed out by Granodiorites (the fourth). Rocks of all suites are I-type, metaluminus and calc-alkaline. All witnesses indicate that this intrusive complex can only be formed by melting of hydrous, calc alkaline, mafic to intermediate, metamorphic crustal rocks. The heat of partial melting of lower crust in Oligo- Miocene time, provided by subduction of Arabian plate under the Central Iran Block. Our study suggests that heterogeneity of crust, AFC processes and diverse conditions of melting are main reasons for differences of these magmatic suites. Geochemical and petrographic signatures indicate that partial melting in dioritic suite has happened under high pressures compared to the other suites.