To substantiate the high velocities of P- and S-waves in the upper mantle of Transbaikalia

Abstract

The results of the analysis of geological, geophysical, and geodynamic studies in the South-East of Transbaikalia are presented in order to substantiate the high speeds of P-and S-waves along the Mohorovichich boundary established here by profile seismic and area seismological studies. The issues of possible anisotropy of the upper mantle were discussed, and the experimental values of Р-and S-wave velocities (according to the data of the GSS and seismology) were compared with the calculations of elastic parameters values based on the approximate mineral composition of probable upper mantle rocks (peridotites, percolates, pyroxenites and eclogites) and experimental values of Р - and S-wave velocities for these rocks obtained at pressures in the upper mantle (up to 10 kbar). By results of discussion of possible causes of increased speeds made the conclusion on the validity of assumptions about the nature of the high-speed block in the mantle of Transbaikalia as the plates eclogites (or eclogitic rocks) in the area of Mongol-Okhotsk orogenic belt.