Fe–Ti–Au–U Mineralization of the Ozerninskii Ore Cluster (West Trans-Baikal Region, Russia)

Comprehensive mineralogical and geochemical studies of gold–brannerite nuggets have been carried out in alluvial deposits of Kamennyi Creek. Its source is located near the central part of the Ozernoe massive sulfide base-metal deposit of the Ozerninskii ore cluster (West Trans-Baikal region). Variations in the composition of the minerals and their relationships are indicative of the complex history of the Fe–Ti–Au–U mineralization. For the first time, the U–Pb age of brannerite has been estimated by the chemical method. The obtained value (200–235 Ma) is fully comparable with the Mesozoic age of quartz syenite–porphyry, granite–porphyry of the Kunalei, and effusive rocks of the Tsagan–Khuntei complexes located as stocks and dikes in the Ozerninskii ore cluster. They characterize the final phases of Early Mesozoic magmatism in the Mongolian–Trans-Baikal magmatic region (195–225 Ma) in the peripheral zones of the mantle plume.