Eocene to Oligocene volcano-plutonic rocks are widespread throughout NW Iran. The Tarom-Hashtjin metallogenic province is one of the most promising epithermal-porphyry ore mineralized districts in NW Iran. The Glojeh gold deposit, located in the center of this province, is a typical high to intermediate sul dation ep- ithermal system, spatially and temporally associated with a granite intrusion and associated high-K calc-alkaline to shoshonitic volcano-plutonic rocks. The intrusive com- plexes of the Glojeh district are characterized by: SiO2 contents of 60.9 to 70.7 wt.%, K2O+Na2O of 7.60 to 8.92 wt.%, and K2O/Na2O ratios of 0.9 to 1.8. They are en- riched in light rare earth elements (LREEs), and large ion lithophile elements (LILEs), depleted in high eld strength elements (HFSEs), and have weak negative Eu anoma- lies (Eu/Eu*= 0.5 to 0.9). 40Ar/39Ar geochronology ap- plied to biotite and feldspar, separated from two intru- sives (Goljin and Varmarziar), and two feldspar aliquots separated from hydrothermal veins at North Glojeh and South Glojeh, was carried out to constrain magmatic and hydrothermal events. Plagioclase (± sericite), from North Glojeh and South Glojeh produced ages (42.20±0.34 Ma, and 42.56±1.47 Ma respectively) that overlap with the age of the Goljin intrusion (41.87±1.58 Ma). Geochemical data for the volcano-plutonic rocks in the Glojeh district, that have87Sr/86Sr isotopic compositions that range from 0.706344 to 0.708331, suggest an origin in- volving partial melting of a depleted mantle source during Neo-Tethyan subduction.
