THREE-DIMENSIONAL SEISMIC HETEROGENEITIES BENEATH THE BAIKAL REGION ACCORDING TO DATA OF LOCAL TELESEISMIC TOMOGRAPHY

Abstract

Application of the Inverse Teleseismic Scheme for data of the International Seismological Center permitted derivation of the 3D structure of seismic heterogeneities at the depth interval between 100 and 700 km beneath the central part of Eurasia, including the Baikal region. This model shows a positive seismic anomaly in the upper mantle beneath the Baikal folded area. At the same time, there is a narrow, highly contrasting, quasi-vertical negative anomaly beneath the southern margin of the Siberian craton, which, reaching a depth of 200 km, shifts toward Lake Baikal. This structure and a model for 3D seismic anomalies beneath the Baikal region at depths down to 70 km, are interpreted on the basis of inversion of local data (sources and receivers are located within the area under study). A strong negative anomaly is observed beneath the Baikal folded area to a depth of 20 km. At the base of the crust it gives way to a strong positive anomaly. Configuration of anomalies beneath the crust is weakly correlated with major surface structures.