A preliminary geoelectrical model of the Karelian megablock of the Baltic shield

Three groups of electromagnetic data have been considered in order to construct a preliminary geoelectrical depth model of the old basement of the Baltic shield: (i) audiomagnetotelluric data in the period range $\text{1}\text{3700}\text{?}\text{1}\text{8}\text{s;}$ (ii) magnetotelluric data in the period range 25–1000 s; and (iii) global magnetovariation-sounding data in the period range >6 h.These data sets fit together on a common apparent-resistivity curve, indicating the existence of a unified geoelectrical model. This model does not support the existence of conducting crustal or asthenospheric layers.