The authorproposes the possibility that a late Paleozoic active margin exists there,which implies that the Suoth and North China Plates could collide firstly along the eastern margin of the North China blate.

Complex of the Zhangsangou Formation is located in the northeastern margin of North China Block, which has been previously considered to be the Paleoproterozoic metamorphic volcanic-sedimentary sequences, mainly according to its metamorphic grade and regional stratigraphic correlation.

Located in the Naiman Banner and southern Hure Banner,Inner Mongoli a,the study area tec-tonically belongs to the Tianshan-Chifeng mobile belt on the northern margin of the North China plate.

Discovery of phosphate concretions in the upper Sinian Fengtai Formation at the southeast margin of the North China block and their implications.;