petrology and u-pb zircon dating of intrusive rocks from a, c-south, and dardvay districts, sangan iron stone mine, khaf

sangan magnetite skarn mine is located 300 km southeast of mashhad, along the eastern part of khaf-drouneh volcanic-plutonic belt. granitoids from three areas within the sangan mine a, c-north and dardvay were studied. within the study area, three intrusive rocks including biotite-hornblende monzonite porphyry, biotite syenite and syenogranite were recognized. based on field cross cutting, absence of garnet-magnetite skarn around the contact, and alteration by younger hydrothermal fluids, these granitoids are older than the magnetite skarn. u-pb zircon age of the granitoid is 42 ma (middle eocene). magnetic susceptibility of the granitoids are 310-900 × 10-5 (si units) and therefore, they are classified as belonging to the magnetite-series (oxidant type) i-type. chemically, these granitoids are metaluminous, alkali-calcic to alkali and shoshonite to ultrapotassic. enrichment of lree, relative to hree and enrichment of lile (sr, cs, rb, k and ba) relative to hfse (nb, ta, ti, hf and zr) indicate that the magma formed in island arc setting. this magma originated from low partial melting (<1%) of garnet-spinel lherzolite (low garnet) and was contaminated in the continental crust. based on the ratio of (la/yb)n 6.23-34.73, indicate that small amount of garnet was left in the source rock. high ration of rb/sr, lile/hfse and high content of k2o, th and nb indicative of continental crust contamination. petrognesis and geochronology of sangan granitoid will help to know more about tectonomagmatic of khaf-kashmar-drouneh volcanic-plutonic belt and their mineralization.