Geodynamics of the western part of the Mongolo-Okhotsk fold belt and tectonic position of gold manifestations in ores in Transbaikalia

Analysis of the geodynamics of the western part of the Mongolo-Okhotsk fold belt and its outlines has permitted a new interpretation of the position o f the western segment of the main branch of the Mongolo-Okhotsk suture, whi ch joints the Siberian and Mongolo-Chinese continents. This suture branch o utlines the Devonian-Carboniferous Daurian and Hentiyn troughs not in the n orthwest, as supposed earlier, but in the southeast, since they corresponde d to the accretion-subduction dine nearby the active margin of Siberia. In the Permian, Triassic, and Early Jurassic, this dine was already part of th e Siberian continent and was the frontal part of the active Andean-type mar gin. The final collision of the Siberian and Mongolo-Chinese continents in the Transbaikalian part of the Mongolo-Okhotsk fold belt occurred at the Ea rly-Middle Jurassic border, but the accompanying tectonic movements and mag matism continued up to the end of the Late Jurassic, when they gave way to rifting. Besides the above-mentioned continents, the Onon island-arc terran e which was <<squeezed>> between them took part in the collision. Therefore , an additional branch of the Mongolo-Okhotsk suture may be distinguished, which outlines this terrane in the east and in the south. It has been established that most of gold manifestations in Transbaikalian ores, which date from the Middle-Late Jurassic, are confined to both branch es of the Mongolo-Okhotsk suture in their new interpretation. This regulari ty is explained by increased permeability of the suture with respect to ore -producing magmatic melts and gold-bearing fluids.