Destruction of the North China Craton: evidence from the Bohai Bay Basin

Guiting Hou, Mohan Yang, and Weihou Yao

The Bohai Bay Basin is a Late Mesozoic-Cenozoic feature of the basins-mountains system in the eastern North China craton. Five mountains around the basin are Yanshan, Taihangshan, Zhongtiaoshan, Taishan and Liaodong. They are block-faulting mountains, not typical orogenic mountains except intraplate orogenic Yanshan Mountain. These mountains constituted the Mesozoic plateau before the destruction of the North China craton. The basin resulted from extension of the North China craton; its formation signaled the destruction of the craton. Based on analysis of the growth indices and section balance for seismic sections from the offshore portion (Bohai Sea) of the Bohai Bay Basin, the growth faults controlled the sedimentation and the migration of the sedimentary depocenter. The depocenters of the basin moved from the margins of the basin to the center of Bohai Sea in the period from the Early Tertiary to the Late Tertiary. The construction of balanced cross-sections and determination of the extension factor (β) for four sections suggest that the extension factors for the offshore portion are higher than those for the onshore portion in the Mesozoic and Cenozoic. These lines of evidence suggest that the extension was greatest in the offshore parts of the craton. This is consistent with the thinnest crust occurring in the offshore portion. The onset of destruction of the craton resulted from the delamination and thinning of thick lithosphere of the plateau, which is evidenced by the presence of NW-trending grabens that occur in an en echelon arrangement on the west of Tanlu Fault Zone and NNE-trending grabens within the Tanlu Fault Zone. Extension-related destruction of the craton was largely dictated by the tectonic evolution of northeast Asia. The offshore (Bohai Sea) portion is the region of the North China craton that Cenozoic extension affected most severely.

This paper represents follow-on research to the authors' 2006 paper in Volume 24 of the Journal of the Virtual Explorer, "Reconstruction of Mesozoic and Cenozoic tectonic figurations of the North China Basin".