Abstract:
We established that there are economic-grade Au and Pt concentrations in the graphitized rocks of the Khanka Massif. Taking into consideration the wide development of regional graphitization of the rocks and their significant thickness (>3000 m), one can suggest the existence of a large Ruzhinka noble metal deposit ascribed to the economic-grade platinoid formation of black shales and metasomatites. In terms of petrochemistry and metamorphic grade, the Ruzhinka rock sequence corresponds to the Voronezh ore association, represented by highly carbonaceous plagiogneisses of the Oboyan Group, with ∼1.3-7.5 g/t Au and up to 5.9 g/t Pt. The studied rocks (at least within the Ruzhinka section) are characterized by an extremely high degree of graphitization and weak sulfidization. On the limbs of the thermal dome, the degree of sulfidization, silicification, and carbonatization of volcanogenic-terrigenous-carbonate protoliths increases with decreasing erosion level. These areas may be promising for Carlin-type gold-platinoid mineralization.