The deep structure of the western boundary belt of the Songliao basin: the geoelectric evidence

The Manzhouli-Suifenhe geoscience transect (GGT) did a comprehensive research on the structure characteristics of the west and east boundary of the Songliao basin. Based on the understanding obtained from the wide-angle seismic velocity distribution, this paper use the 2D geoelectrical distribution along a section (about 470 km, 42 survey points) of magnetotelluric sounding newly carried out near the western boundary of Songliao basin to describe the detailed deep structure feature of the west boundary. Compared with the Manzhouli-Suifenhe geoscience transect, the similar result is that the fault structure of the west boundary shows that the Nenjiang fault as the west boundary of the basin stacks together with the Heihe-Hegenshan suture zone near the earth's surface, and the two faults separate down several kilometers, and the fault of the suture zone tends to the west through the crust, but the Nenjiang fault tends to the east and is perhaps within the crust. The difference from the Manzhouli-Suifenhe geoscience transect is in the structures under the part where the two faults separate. Because of the effect of the complex regional stress field, such as the collision and welding between the Xing/an micro-plate and Songnen micro-plate and the boundary strike-slip fault, the retained lithosphere fragments is divided into the both sides of the Nenjiang fault. The established geological-geophysical interpretation model provides the feasible geological construction process of the western boundary.