Features of the electric structure of the lithosphere beneath the Hinggan-Inner Mongolia and Jilin-Heilongjiang regions

Abstract: Two-dimensional (2D) inversion and integrated interpretation of the gathered MT data were made by using 2D continuous automatic inversion technology and 2D electric structure cross-sections of the MT profiles were obtained in different areas. The 2D inversion cross-sections show that the eastern and western boundaries of the Songliao basin are steeper while the southern boundary is gentler and that low-resistivity objects are commonly present at 15-30 km depth in volcanic areas, which offers a basis for interpreting the existence of a magma pocket at depth of volcanic areas. In addition, the cross-section of 2D inversion of the MT data re-surveyed along Huanan-Laohe has also clearly revealed the following: the western segment of the cross-section has a high resistivity feature and a persistent lithospheric thickness (80-90 km), corresponding to the Jiamusi massif. The central segment of the cross-section obviously contains an electricity gradient zone, which furnishes a basis for the determination of the eastern boundary of the Jiamusi massif and its deep structure configuration. The eastern segment of the cross-section reveals a thrust nappe at shallow depth in an area east of the Jiamusi massif and an electric structure composed of alternate high-resistivity strips and low-resistivity strips at depth.