THERMAL METAMORPHISM OF Au-Ag ORES OF THE NYAVLENGA DEPOSIT (NORTHEAST RUSSIA)

Abstract

The formation of several epithermal Au–Ag deposits in the Okhotsk–Chukot volcanogenic belt (OCVB) is closely associated with the recurrent activation of hydrothermal systems over a long period extending from the Late Jurassic to the Paleogene. Ores of the Dukat, Nyavlenga, and other deposits, which formed at early stages of volcanism, were rejuvenated in the course of plutonic magmatism that promoted the redistribution of mineral matter. Thus, orebodies of epithermal deposits formed in the course of sequential increase in temperature (“progressive” mineralization), rather than the conventional hydrothermal scenario of a decrease in temperature from the early to late stages.