THE MAIN STAGES OF THE FORMATION OF THE GOLD AND RARE-METAL MINERALIZATION OF THE EASTERN TRANSBAIKALIA AND ASSOCIATED MAGMATISM: NEW U-Pb AND Ar-Ar DATA

The article presents new data on the age of ore-bearing magmatism and associated ore mineralization on the example of large gold, gold-bearing (Lugokan, Kultuma, Bystrinskoye, Bugdainskoye, Lugiinskoye, Antiinskoye) and rare-metal (Belukha, Bukuka, Antonovogorskoye) deposits located within the Aginskaya and Argunskaya structural-formational zones of the Mongol Okhotsk fold belt. The LA-ICP-MS and Ar-Ar methods were used to determine the age of the igneous rocks, and the age of the ore mineralization was determined using the Ar-Ar dating method. The obtained new geochronological data, together with the published data, made it possible to identify new stages and phases, as well as to supplement and expand our understanding of the age of various mineralization and its relationship with magmatism. Stage I (Middle Triassic) - Au mineralization -> Stage II (Middle-Late Jurassic, collision): first phase - Mo-, Fe-skarn, Au-As, Au-Cu mineralization and early "impulses" or phases of the Shakhtama and Amujikan-Sretensky complex -> the second phase of W-, Au-polymetallic, Au-Bi-mineralization and late "impulses" or phases of the Shakhtama and Amujikan-Sretensky complex -> Stage III (Early Cretaceous, riftogenic) Au-Ag, Sb-Hg and Au-As mineralization, and also W-mineralization associated with igneous rocks of the Kukulbey intrusive complex. A favorable factor for the formation of large complex deposits is the "variegation" of magmatism and its wide intrusion interval, one example of which is the Bystrinskoye deposit. The obtained data on the age of ore mineralization and magmatism at the Bystrinskoye deposit show that the formation of the Bystrinskaya ore-magmatic system proceeded for a long time and is associated with both Late Jurassic magmatism and later processes.