Gold in Mineralized Volcanic Systems from the Lesser Khingan Range (Russian Far East): Textural Types, Composition and Possible Origins

While gold partitioning into hydrothermal fluids responsible for the formation of porphyry and epithermal deposits is currently well understood, its behavior during differentiation metal-rich silicate melts still subject an intense scientific debate. Typically, scavenged sulfides crustal fractionation sulfur-rich mafic to intermediate magmas development native forms alloys this important precious metal in igneous rocks associated ores are poorly documented. We present new data on (Cu-Ag-Au, Ni-Cu-Zn-Ag-Au, Ti-Cu-Ag-Au, Ag-Au) from iron oxide Lesser Khingan Range (LKR) Russian Far East. Gold alloy particles 10 100 µm size irregular spherical shape. spherules were formed through silicate-metal liquid immiscibility then injected fissures surrounding ascending melt column, or emplaced a volcanic eruption. Presence globular (occasionally with meniscus-like textures) Cu-O micro-inclusions Cu-Ag-Au confirms their crystallization via extremely fast cooling. Irregularly shaped alteration gold-bearing ores. Association primarily iron-oxide mineralization LKR indicates possible involvement silicate-metallic explosive volcanism Andean-type gold-copper (IOCG) related copper-gold deeper parts sub-volcanic systems. Thus, deep roots arc volcanoes may serve as precursor exploration guide high-grade at shallow structural levels hydrothermal-volcanic environments subduction zones.