First Data on the Age and Geodynamic Settings of the Formation of Gold–Sulfide–Telluride Quartz Vein Mineralization in the Middle Urals

Granitoids with gold–sulfide–telluride quartz vein mineralization in the Middle Urals are dated for the first time. The object of study includes the albitized porphyry granites of the Bynga stock with related quartz veins and beresite–listvenite metasomatites of the eponymous deposit, which are located at the endo- and exocontact zones. The quartz veins contain abundant native gold, as well as tellurides of Au, Ag, Bi, Hg, Cu, and other metals. The age of the least altered rocks of the Bynga stock is 394.7 ± 3.1 Ma (the end of the Emsian Stage of the Early Devonian) is determined using the U–Pb method by zircon grains (SHRIMP-II, Center of Isotopic Studies, Russian Geological Research Institute, St. Petersburg, Russia). Our data indicate that the formation of granites of the Bynga stock and comagmatic country volcanic rocks was related to the Devonian island-arc magmatism, which occurred on the territory of the eastern sector of the Middle Urals from the second half to the middle of the Frasnian Stage. By the age and geodynamic setting, the gold–sulfide–telluride quartz vein mineralization differs from gold–sulfide quartz veins, which are devoid of tellurides. According to the available data, the latter mineralization in the Middle Urals formed 315–300 Ma during the early episodes of collision magmatism. The higher Te content of postmagmatic ore-bearing fluids, which were generated in an island-arc geodynamic setting, was most likely caused by the related generation of granitoid and coeval mafic melts with a higher Te content.