Crustal Structure and Comparison of Different Tectonic Blocks in North China

Abstract

The North China paleocontinenal block has undergone reconstruction through multi-stage tectonic movements, resulting in distinct characteristics of crustal subdivision. Based on data and study results of nearly 30 profiles of deep seismic sounding with a total length of about 20000km, we make a further study on the fine structures of the sub-blocks of the crust beneath North China and comparison of their differences. According to the structural features, the crust of North China can be classified into 3 types. The first is a simple crustal structure in the Ordos basin in the western part of the region, with an integrated basement structure, showing the crustal structure feature of stable paleocontinent. The second is a relatively simple crustal structure in the Taihang mountain located in the middle part, and the Yinshan mountain and Yanshan mountain in the northern part. These are uplifted zones where slight velocity reversal exists in local areas of the middle and lower crusts which is possibly related to medium decoupling deformation within the crust caused by the regional crustal thickening and uplifting. The third is a complex crustal structure in the rift-depression basin in the eastern part of North China, with a sinking and fragmentized basement, loosen media within the crust, low velocity, uplifted Moho, thinned crust, and obvious lateral structural differences, showing tectonic features of the newly reconstructed crust. Based on these analyses, we discuss the crustal block-subdivision tectonics and related dynamic evolution in North China in a comprehensive manner.