Geochemistry, tectonic setting and petrogenesis of Sefidkuh granitoid rocks and comparison with Shahkuh granitoid, West of Nehbandan, East of Lout block

The Sefidkuh granitoid and Shahkuh granitoid are located in southwest of Nehbandan city (South Khorasan province) and east of Lut Block. The Shahkuh granitoid rocks made of two main units by combining monzogranit-granodiorite and syenogranite and its major mineral are quartz, plagioclase, alkali-feldspar, biotite and amphibole. The Sefidkuh granitoid is contain composition range of granite (monzo and syenogranite), granodiorite and composed of the mineral quartz, plagioclase, microcline, orthose and biotite. The plagioclase composition of the Sefidkuh granitoid rocks is often andesine and sometime is albite, it is all andesine in the enclaves of Sefidkuh and Shahkuh and its granodiorite unit, and its oligoclase to andesine in Shahkuh granitoid unit. The biotite composition of Sefidkuh felsic and Shahkuh mafic enclaves is magnesium biotite type, Shahkuh granodiorite is ferrugineous biotite to magnesium and Sefidkuh granite massif and Shahkuh syenogranite unit are ferrugineous biotite and both massif are first magma types. The study of the mineral chemistry and geological masses suggest that these masses belong to calc-alkaline magma related to active continental margin. In the changes to the chondrite- normalized trace element diagrams, rock of this figures are enriched by LILE and LREE, depletion of HREE and HFSE and negative anomalies Sr, Ti, Nb, and Ba indicate that they are compatible with characteristic of the rocks depend on the active continental margin environment. The tectonic discrimination diagrams, show the dependency of shahkuh granitoid massif to the simultaneously dealing environment (syn- collision), and Shahkuh granodiorite massif with volcanic arc subduction (VAG). The petrogenetic diagrams indicated that Shahkuh granodiorite is from a source of amphibolite, Sefidkuh granitoidis from a source of metagreywackes and Shahkuh syenogranite have been achieved from a source of amphibolite to felsic pelite.