New type of noble metal mineralization in the graphite formation of the Khanka terrane, Russian Southeast

Abstract

Noble metal–graphite mineralization has been identified in the Riphean–Cambrian metamorphic complexes of the northern Khanka terrane, Russia. The graphite mineralization is hosted in magmatic and sedimentary rocks metamorphosed under greenschist to granulite facies conditions. This paper provides the results of our study of the Turgenevo–Tamga graphite deposits. This study analyzes the geochemistry of the noble metals with the aim of determining the spatial relationships between noble metals and graphite. The graphitized rocks, analyzed by various geochemical methods, show a wide range of noble metal concentrations (ppm): Pt (0.02–62.13), Au (0.02–26), Ag (0.56–4.41), Pd (0.003–5.67). Crystallization from gas-condensates is indicated by the relationships between the noble metal mineralization and the graphite, and in particular the inhomogeneous distribution of graphite in the rocks, the inhomogeneous distribution of metals in the graphite, the microglobular graphite structures, and the carbon isotopic compositions. Our conclusion is that the noble metals and graphite mainly originated from magmatic fluids, but that some material was derived from exogenic and metamorphic sources.