Home – Home – Jornals – Russian Geology and Geophysics 2003 number 1-2

On the basis of generalized new data on regional and thematic researches, the main problems involved with the evolution of the Paleoasian ocean and structure of the huge Ural-Mongolian fold belt are considered.
Some segments of the Ural-Mongolian fold belt formed at different stages of the evolution of the Paleoasian ocean developed in a specific fashion. Hence, Altaides, Kazakhstanides, Tien-Shanides, Uralides, Salairides, and Baikalides may be recognized within its limits. At the same time, the main stages of development of separate structures are well correlated with each other, and the paleomagnetic data and palinspastic reconstructions confirm the common evolution of the Paleoasian ocean in the range of 950-250 Ma.
The large stages of reconstruction and closure of the Paleoasian ocean are involved with superplumes, which appeared in the Permian-Triassic (Siberian), in the Devonian (European), and, possibly, in the Early-Middle Ordovician. These plumes also favored the synchronization of events in separate parts of the Paleoasian ocean. The best synchronization is observed in the periods of superplume appearance at about 485, 360, and 245 Ma, and about 120 Ma in the Mesozoic, at intervals of 120 myr. The presence of these superplumes is hypothesized in the Late Precambrian as well, in a lapse of 120 myr, thus reaching the best synchronization at around 610, 730, and 850 Ma. In the periods between these major plumes, smaller local plumes appear at an interval of about 30 myr and, correspondingly, local synchronization of tectonic processes occurs (rearrangement of island arcs and related local collisional processes, exhumation of eclogites and glaucophane schists, reflected in the maxima of isotope ages).