Oldoi gold placer system of the Amur gold-bearing province

In the work, the authors have considered geological – structural position and regularities of placers and root sources location at the Oldoi gold-bearing system. It is situated on the area of Berezitovy ore-placer node (RRU) of the Amur gold-bearing province. The node is an isometric, rounded central type structure with fragments of radial and annular faults. The core element of the gold-bearing system is the Oldoi River valley with the Khaikta River tributary, which crosses the geological structure of the central type in the northeasterly direction. River valleys are rich with placers. More than 50 tons of gold have been extracted from them. The valleys are oriented along fragments of radial or concentric faults. The authors have given characteristics of placer groups, indicating the volume of production and typomorphic features of native gold. The gold in the placers is small and medium-sized. The goldenrods shapes range from lamellar and pellet-shaped to scaly. Quite often the nuggets are come upon weighing up to 1.8 kg. In most placers gold is highly valuable. It has been stated that the sources of the Oldoi gold-bearing system are located on its periphery and saturated with Paleozoic and Mesozoic intrusive formations. They are represented in the northwestern part of the system by the Berezitovoye gold-polymetallic deposit and manifestations of gold-polymetallic, gold-sulfide-quartz and gold-quartz formations (Sergachinskoye and Khaiktinskoye ore fields). In the northeastern part, the source of placers is the gold mineralization of the Mongolian ore field with manifestations of gold-sulfide-quartz and gold-quartz formations. On the southern periphery of the placer system, the root sources are represented by manifestations of gold-mercury and gold-sulfide formations. The future prospects of the gold mining industry lie in the identification, exploration and exploitation of new gold deposits, including the gold-mercury formation, unconventional for the Amur region.