Contribution of biogenic and volcanogenic factors to formation of ferromanganese nodules of Olkhon Island (Lake Baikal)

The first data on the structure, textural features, and geochemical and mineral composition of Fe–Mn nodules of the Sasin Formation, Olkhon Island (Baikal), have been determined. A significant role in the formation of the nodules was played by hydrothermal processes with varying contributions of hydrogenic factors. The presence of reduced inclusions in the nodules and their textural features indicate the presence of various components of organic matter in the nodules, creating the conditions for local concentration of ore components. Activation of hydrothermal processes is typical for the Baikal Rift Zone in the Late Miocene–Early Pliocene, which is reflected in the composition of Fe–Mn nodules from the Sasin Formation.