Possible Source of Sulfur in the Porphyry Cu-Mo Ore-Magmatic System: Evidence from the Zhireken Deposit, Eastern Transbaikalia

摘要

Large porphyry Cu-Mo deposits containing hundreds of million tons of ore with high S/(Cu + Mo) values within commercial ore stockworks are surrounded by wide (up to 0.5 km or more) pyrite halos. Thus, such deposits represent a giant sulfur reservoir in the earth's crust. Therefore, deciphering their genesis provides insight into the source of sulfur. This primarily concerns deposits related to the evolution of ore-bearing granitoid-dominated porphyry complexes. As was reported in [1-5 and others], the granitoid magmas of some porphyry Cu-Mo ore districts have sulfur contents that are too low (only up to 100 ppm) to provide a complete sulfur balance in the ore-magmatic system. In particular, the amount of sulfur in melt is estimated at 2500-5000 ppm for the ore-forming quartz-diorite magma in the Santa Rita copper deposit (United States), where anhydrite phenocrysts were found in dikes of the same composition. This amount is more than an order of magnitude higher than that in the ore-is bearing granite magmas.