Fig. 2: Electrical conductivity images of the mantle beneath the study area.

Conductivity slices at depths of (a) 410–520 km, (b) 520–660 km and (c) 660–900 km. Coloured dots with three-letter codes in (a) represent the geomagnetic depth sounding (GDS) stations listed in Tab. S1, with the colours indicating the root mean square (RMS) of the data misfit at the end of the inversion. The areas enclosed by solid and dashed black lines denote the locations of the Siberian Traps (ST) when they formed4 and the Perm anomaly near the core-mantle boundary14, respectively. The PEC denotes the Perm electrical conductivity anomaly. The blue line with an arrow indicates the subduction direction and front of the Hellenic (HEL) slab39,66. The black line labelled I–I’ in (b) marks the location of the vertical section in (d). \({\sigma }_{0}\) is the global average conductivity. d Electrical structure beneath the I–I’ profile along 51°N in (b). Dashed white lines, which are vertically exaggerated, show the depressed 410-km and elevated 660-km discontinuities43. Dashed red lines in (c, d) denote low-velocity bodies40.