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