The lithosphere of North China Craton from surface wave tomography

Fundamental mode Rayleigh wave group velocity dispersion data were used in a tomographic study to reconstruct the crust and upper mantle shear velocity structure in east Asia. This article expounds the features of lithosphere structure in different sub-regions of North China, and discusses their implications for the tectonic evolution and present tectonics of North China Craton (NCC). The study revealed that strong earthquakes took place in the low velocity zones and along the boundaries between high and low velocities in the middle and lower crust; the active NW-trending Zhangjiakou–Bohai seismic belt corresponds to a prominent low velocity zone in the crust and upper mantle lid. In addition to the well-known structural difference between western and eastern NCC, we are able to resolve clearly the lithospheric features of sub-regions in eastern NCC. The southern North China Basin and north Yellow Sea are characterized by a high velocity crust and upper mantle lid down to 70–80 km depth, while the northern North China Basin has a low velocity crust and the velocity below Moho to about 130 km is rather uniform and low. There is also a general trend of velocity decrease in the upper mantle from west to east. The velocity images bear the imprints of subduction and collision that took place in the periphery of NCC since Mesozoic, and shed some light on the mechanism of Mesozoic lithospheric thinning of eastern NCC.