The Thickness of the Lithospheric Plate and the Parameters of the Asthenosphere beneath the Scandinavian Shield according to the BEAR Experiment

The article summarizes the works on studying the upper mantle structure beneath the Scandinavian Shield from the magnetotelluric (MT) data of the BEAR experiment combined with the global magnetovariational (MV) data. During the past few years, we improved the technique of joint interpretation of MT and global MV data, which enabled us to draw more reliable conclusions concerning the structure of the upper mantle and outline the ways of further increasing the efficiency of the MT method in determining the thickness of the lithospheric plate and geoelectrical parameters of the asthenosphere. Our study of the upper mantle structure from the BEAR data suggests the presence of the asthenosphere at a depth of 200 to 300 km with the electric resistivity of 20-40 Omega m, which corresponds to a 1-2% melt of the mantle material. For obtaining more exact estimates, the BEAR data should be interpreted together with the MV data from the observatories located in the Scandinavian Shield. In the future, this approach will probably enable a more reliable zoning of the Scandinavian shield according to the thickness and depth of the asthenosphere.