Structure and age of the fluorite-berillium deposit of the field Rainbow, Western Sayan Mountains: to the problem of assessment of metallogenic prospects of the territory

The age and geochemical parameters of the muscovite-fluorite-euclase-beryl Raduga deposit, which is located within the Kizir-Kazyr zone of rare-metal magmatism, are determined. In contrast to other deposits and ore occurrences of the zone, represented by alkaline granites characterized by rare metal mineralization, the Raduga deposit is associated with metasomatites in carbonate rocks. The age of the deposit, estimated at ⁴⁰Ar/³⁹Ar by the muscovite method of beryllium fluorite-muscovite greisens, is 469.3± 4.5Ma. It corresponds to the age of the ore-bearing alkaline granites of the zone. The dikes which occur within the deposit are identical by the composition to the dikes of rare-metal alkaline granitic massifs, one of which is located in a few kilometers from the deposit. The nature of the ore Be-Li mineralization of the deposit is in good agreement with the geochemical specialization of the Early Paleozoic Kizir-Kazyr metallogenic zone. The revealed features of the relationship between Raduga deposit and rare-metal deposits in alkaline granites suggests a variety of mechanisms involved in the formation of rare-metal deposits of the Kizir-Kazyr zone. Thus, it allows to expand approaches for prediction and exploration of rare-metal deposits in the region.