COBALT MINERALIZATION IN THE ALTAI-SAYAN OROGEN: AGE AND CORRELATION WITH MAGMATISM
The paper discusses the spatiotemporal and genetic relationships of hydrothermal Co mineralization in the Altai-Sayan orogen with mafi c, alkaline mafi c, and granitoid magmatism on the basis of isotopic, geochemical, and geochronological investigations. Four stages of Co mineralization have been distinguished for this region: Early Devonian (D1), Late Devonian-Early Carboniferous (D3-C1), Permo-Triassic (P2-T), and Early Cretaceous (K1). They correspond to periods of large-scale mafi c magmatism. Isotopic (Pb, Sr, He) and geochemical studies have shown that Co mineralization is genetically related to mafi c and granitoid magmatism. Also, these studies have confi rmed that Co deposits formed with the participation of mantle fl uids and are related to chambers of mafi c and alkaline mafi c melts. Besides, it has been found that ore originated both from magmatic sources and host rocks. A pulsed facies endogenic zonation has been established for Co deposits, Cobearing ore clusters, and zones with high-temperature Co-As and low-temperature Ni-Co-As mineralization. It has been fi rst established that ores at hydrothermal Co deposits are rich in Pt and Pd.