RE-DELIMITATION OF THE DEMARCATION LINE BETWEEN THE INNER MONGOLIA GEOSYNCLINE AND THE NORTH CHINA PLATFORM BASED ON THE DATA OF SEISMIC SOUNDING AND TELLURIC ELECTROMAGNETIC SOUNDING

摘要

The demarcation line between Inner Mongolia geosyncline and North China platform, that has been delimitated newly, is a deep lithospheric fracture, great differences are shown on the north side of and on the south side of the fault line, and the structures of seismic interval velocity have a greater difference. The Moho depth contours lines, the negative anomaly zones and the gravitational gradient zones in the northern margin of North China platform all spread out in east-west-trending lines. The differences mentioned above can be caused through different formation periods, different crust structures and different materials constitutions etc. Therefore, on the south side of the fracture line is North China platform, and on the north side is Inner Mongolia geosyncline. This demarcation line had been formed during Palaeozoic Era.