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Introduction Granitoids are the main rock units in the continental crust. Study of granitoids reveals significant information on tectonic mantle and upper crust. Many researchers have investigated petrogenesis and origin of granitoids (e.g., Chappell and White, 2001; Barbarin, 1999; Frost et al., 2001). For example, Chappell and White (1992), Pitcher (1993) and Chappell et al., (1998) have divided granites into two major groups of: (1) I-type granites (high-temperature or Cordellerian granitoids, including low-K granitoid to high-Ca tonalite, without inherited zircons) formed by partial melting of mafic rocks at >1000 ℃ in mantle or subduction zones of continental margins, and (2) S-type (low-temperature or Caledonian granitoids with inherited zircons) granites formed by partial melting of felsic crust at ~700-800 ℃. Northeast of Iran is a key location for studying the Cimmerian Orogeny, which is related to the Late Triassic collision between it and Eurasia, and the closure of the Paleo-Tethys (Samadi et al., 2014). Mesozoic Mashhad granitoids have cropped out along with the Paleo-Tethys suture zone. Distinct granitoid suites, i.e., monzogranite, granodiorite, tonalite, and diorite occur in Mount Khalaj located in the south of Mashhad. It comprises of monzogranite and granodiorite. However, monzogranite is the most abundant. To study the plutonic events during the Turan and Central Iran collision, the origin and tectonic setting of monzogranite of Mount Khalaj are investigated in this study based on whole rock geochemical data. Materials and methods This research study is based on field studies and petrography. Fresh thin sections samples were selected for geochemical analysis. Whole rock composition was measured on pressed powder tablets by X-ray fluorescence (XRF) using a Philips PW 1480 wavelength dispersive spectrometer with a Rh-anode X-ray tube and a 3 MeV electron beam Van de Graaff Accelerator, at the center for Geological Survey of Iran. The trace element data of a sample was measured at the Activation Laboratories, Ontario, Canada (ActLabs). Samples were digested by lithium metaborate/tetraborate fusion and analyzed with a Perkin Elmer Sciex ELAN 6000, 6100 or 9000 ICP/MS. GCDkit 4.1 and CorelDraw software packages were used for plotting diagrams and calculation of saturation temperatures. Results The Khalaj granitoid is mineralogically composed of quartz, potassic feldspar, plagioclase, mica, and accessory minerals of zircon and apatite. Geochemically, it is an unaltered acidic intrusion with ~72-73 wt.% SiO2. It is a granitoid (monzogranite) based on various classification diagrams (e.g., Cox et al., 1979; etc.). It shows the peraluminous nature (A/CNK~ 1.08-1.24) with negative Eu anomaly of ~0.62-0.73 (Eu/Eu*

The Ghaidou monzogranite in the southeast of Khomein constitute a part of rock complex from the northern part of the Sanandaj-Sirjan zone. This body intruded into the Jurassic micaschists and created a metamorphic aureole. Also, aplitic veins, tourmaline bearing pegmatitic dikes, felsic microgranular enclaves and surmicaeous enclaves are observed in this area. The predominant minerals of these rocks are K-feldspar (orthoclase and microcline), Na-plagioclase (Albite-oligoclase in the monzogranite and oligoclase in the felsic microgranular enclaves), quartz and black mica (Annite) -as the main mineralswith minor amount of tourmaline (schorle), garnet, white mica (phengite), sillimanite, kyanite, zircon, apatite and ilmenite. On the basis of biotites mineral chemistry, these phases are enriched in FeO and Al2O3 and relatively low in TiO2. These minerals are magmatic and primary and thermometry results yielded 660-690 °C. According to the chemical composition of primary igneous biotites in the enclaves and monzogranites, these rocks have calc-alkaline, peraluminous and an orogenic continental collision affinity characteristics of S-type granites. Also, the biotite composition and the presence of ilmenite point to low oxygen fugacity and redox conditions during magma crystallization. Based on the available data, the generation of these rocks can be related to Arabian-Eurasia collision zone. [ABSTRACT FROM AUTHOR]