Linking cu mineralization to host porphyry emplacement: Re-Os ages of molybdenites versus U-Pb ages of zircons and sulfur isotope compositions of pyrite and chalcopyrite from the IJU and sarkuh porphyry deposits in southeast Iran

The Kerman copper belt in Iran contains a number of important porphyry copper deposits, including Sarkuh and Iju. Molybdenite Re-Os isotope dating of the Sarkuh and Iju porphyry copper deposits shows that mineralization occurred at 15.14 ± 0.08 and 9.8 ± 0.06 Ma, respectively. Compared with the previous Re-Os dating of molybdenite in the region, it is revealed that Cu mineralization was an ongoing process in an arc setting during the Miocene. The available zircon dates of the granitic rocks from the Sarkuh (15.18 ± 0.43 Ma) and Iju (9.27 ± 0.50 Ma) porphyry copper deposits indicate that the mineralization occurred contemporaneously with the emplacement of collision-related ore-hosting porphyries. The Re content (1,715.40 ppm) of molybdenite and the δ³⁴SCDT values (0.05‰) of pyrite-chalcopyrite from Iju are consistent with its origin of sulfur and metals from a dominantly mantle source. However, the lower Re content (302.21 ppm) of molybdenite and higher δ³⁴SCDT values (3.20‰) of pyrite-chalcopyrite from Sarkuh suggest additional contributions from crustal materials. It is likely that the younger porphyry copper deposits in the Kerman copper belt, such as Iju, are related to the greater contribution of postcollisional mantle-derived magmas, while the older deposits (e.g., Sarkuh) were formed during the collisional event at the Oligocene-Miocene interval where the magma had some additions from the lower crustal melts generated during crustal thickening.