Distribution of rhenium in molybdenite from porphyry Cu-Mo and Mo-Cu deposits of Russia (Siberia) and Mongolia

Rhenium was determined in representative molybdenite samples (concentrates) from the Aksug, Erdenetuin-Obo, Zhireken, Shakhtama and Sora porphyry Cu-Mo and Mo-Cu deposits of Russia (Siberia) and Mongolia. The Re contents in the majority of the concentrates are low, ranging from 6 to 460 ppm. The maximum Re contents were determined in molybdenite concentrates from the Aksug (460 ppm Re) and Erdenetuin-Obo (199 ppm Re) Co-Mo porphyry deposits and are significantly higher than those from the Zhireken, Shakhtama and Sora Mo-Cu porphyry deposits. The Re content of molybdenite concentrates from the studied Mo-Cu porphyry deposits (6 to 57 ppm) are, however, comparable to those from comparable deposits worldwide. The Aksug and Erdenetuin-Obo deposits, with relatively elevated Re content, differ from the Zhireken, Shakhtama and Sora deposits with lower Re contents in terms of (1) higher Cu/Mo ratio; (2) lower δ34S and 87Sr/86Sr values; (3) silica and alkali contents of the host rocks; (4) the alteration type of the associated rocks; (5) the elevated Cl activity in the fluid; (6) the lower temperature of the molybdenite formation; and (7) the higher oxidized conditions. The Re contents of molybdenite from porphyry Cu-Mo deposits may therefore be related to the composition of parent magmas themselves and/or fractionation, sources of the material, and variations of physical and chemical conditions of crystallization (fO2, Cl activity, P, T).