Mesozoic-Cenozoic extension of the Bohai Sea: contribution to the destruction of North China Craton

摘要

The Bohai Sea is a Late Mesozoic-Cenozoic feature of the basin-mountain system located in eastern North China Craton (NCC). The Late Mesozoic thinning of the lithosphere signals the early destruction of the NCC. The onset of the destruction was due to the delamination of thick lithosphere of the craton, represented by the NW-trending grabens in an en-echelon arrangement west to Tanlu Fault, and by the NNE-trending grabens within the Tanlu Fault Zone. The Late Mesozoic NW-trending grabens are overprinted by structures related to the Cenozoic NE-trending pull-apart basin with very thick Mesozoic-Cenozoic sediments in the eastern NCC. C-frequency diagrams of growth faults and the extension factor (β) of four sections across the basin suggest that the extension migrated from the margin to the center of Bohai Sea, and that the Mesozoic and Cenozoic extension factors for Bohai Sea are higher than that of the margin. These evidences suggest that the greatest extension occurred in the center of Bohai Sea, which is consistent with the thinnest crust being found in the center of the sea. The extension ratios and tectonic evolution of the Bohai Sea suggest that it is the key region for the destruction of the NCC, as evidenced by the topography. However, the NCC experienced two stages of destruction with the late stage related to the tectonic regime of Northeast Asia.