Crust structure of the North China Craton from a long-range seismic wide-angle-reflection/refraction data

Abstract

We present an interpretation of a 1530-km-long wide-angle seismic reflection/refraction profile that extends across the North China Craton (NCC) approximately from east to west. This profile is the longest and the densest wide-angle seismic reflection/refraction profile in China up to now. Parameterizing the velocity model as layers with variable thickness, we perform seismic travel time tomography to resolve the velocity variation within layers and velocity contrast across Moho. Our model shows crustal thickness that varies from 35km under the Shandong peninsula, to 30km under the North China Plain (NCP) and 32–40km under central NCC, to 45km under the Ordos plateau. These results indicate obvious crustal thinning beneath the NCP in comparison with the ~35km crustal thicknesses typical of most cratonic regions. In particular, an abrupt Moho step of ∼10km is detected at the junction of the eastern block and western block of the NCC. These crustal characteristics are consistent with studies of lithosphere–asthenosphere boundary (LAB) with the method of receiver function migration, and they indicate a close correlation with lithospheric thickness and surface tectonics of the northeastern NCC. These results provide robust seismological evidence that the lithosphere from NCC to the western edge of the Taihang Mountain, might have been widely affected and thinned since its formation in the Archean era.