The Features of the Deep Velocity Structure of the Trans-Baikal Section of the Central Asian Fold Belt from the Seismological and DSS Data (Alignment of the 1-SB Reference Profile)

Abstract

The materials of deep seismic studies carried out on the 1-SB reference geophysical profile and the areal interpretation of the seismological data obtained in the Trans-Baikal part of the Central Asian Fold Belt are presented. It is shown that longitudinal and transverse waves were recorded from the reference boundaries within the crust and the Moho surface in the Trans-Baikal region using explosions and powerful vibration sources on the 1200-km long 1-SB geophysical profile. The inhomogeneous upper crust velocity structure down to 15–20-km depths and the Moho surface was revealed from P- and S-waves. The anomalous mantle, which exhibited decreased boundary velocity values of P- and S-waves at 7.8–7.95 km/s and 4.3–4.5 km/s, respectively, was reliably traced within the Baikal Rift Zone from the DSS and seismological data. In the southeastern part of the area (the central Mongol-Okhotsk Orogenic Belt and adjacent folded structures of the Trans-Baikal region) a layer of increased P-and S-wave velocity values of 8.4 ± 0.15 km/s and 4.9 ± 0.05 km/s, accordingly, was detected at the mantle surface. A comparison was made with the materials of other studies.