The Conditions of Formation for Epithermal Ag‒Au Mineralization at the Televeem Volcano Dome Rise, Central Chukchi Region

This paper considers the conditions of formation for the epithermal Au–Ag mineralization at the Televeem volcano dome rise (VDR) lying in the Central Chukchi sector of the Okhotsk–Chukchi Volcanogenic Belt (OChVB). New data are provided for the composition, distribution, and concentrations of rare elements, including REE, in epithermal ores, and the PТ parameters of ore-forming fluids. Appreciable enrichment of REE samples, the dominance of light lanthanoids over heavy ones, very low Eu/Sm ratios ( $$ \ll 1$$ ), slightly inclined near-chondrite distribution patterns with well-pronounced europium minima, are all typical features for the VDR epithermal ore-forming system. The values of Ce/Ce* vary between low negative and moderately positive (between 0.81 and 1.38), while the Eu/Eu* ratio varies between 0.28 and 0.7, which provides evidence of oxidating conditions prevalent during the mineralization. The results of thermal and cryometric studies of fluid inclusions in quartz have revealed that the ore-forming fluid contained chlorides of Na, Mg, and K, the epithermal mineralization was deposited by homogeneous hydrothermal fluids with salt concentrations (0.3–6.2 wt %-equi. NaCl), the fluid had density 0.60–0.87 g/cm3, the temperatures were 203 to 343°C, the pressure of water vapor varied between 40 and 140 bars. The geochemical data and the PТ parameters of the ore-forming fluids showed that the mineralization was of the low sulfidation epithermal class. These data indicate andesitic magmas and meteoric waters as the most likely sources of the fluids. The information provided in this paper is of practical importance for regional metallogenetic prediction, for the search for and evaluation of epithermal Au‒Ag deposits.