Petrology of granitoid rocks in the northwest of Ahangaran(Dezg area, Souteast of Qaeen, eastern Iran)

The study area is located in Sisitan suture zone, eastern iran, south Khorasan, 90 Km southeast of Qaeen and around of Dezg village. The plotonic bodies in this area consist of Diorite, quartzmonzodiorit, granite, granodiorite and tonalite. plagioclase, quartz, alkali feldspar (Orthose and microcline), biotite and green hornblende are main components and pyroxene, sphen, apatite and magnetite are minor minerals. Granular, poekilitic, graphic, zoning, Sieve and Ridged texture is common. Sericitic, choloritization, Oxidation, Kaolinization and epidotization alteration observed in this plutons. The studied rocks belong to calc-alkaline series and are alumina to peraluminous. The classification of these masses belong to I-type granitoids and magnetite series. Increasing trend diagrams MnO, Al2O3, FeO, CaO, MgO, TiO2 and P2O5 versus SiO2 and decreased Na2O and K2O versus SiO 2 diagrams indicate the origin of this samples. Variation diagram of trace elements versus SiO2 show a decreasing trend for the elements Co, Sr, Sc and V because substitution in minerals containing iron, magnesium and titanium. Increasing trend of Ba, Rb and Zr minerals because of the succession of these elements in compounds of plagioclase and partly hornblende instead of calcium. Based on geochemical characteristics, the masses are of magmatic origin. Tectonic setting of study masses is volcanic arc granitoids that represents subduction Setting in which a row of orogenic granitoids are related to active continental margin. These magma mass is derived from mantle wedge metasomatism composition amphibolite (metabasite)

Keywords:

I type granitoides , mantle wedge , Dezg village , Sistan suture zon.