Cenozoic destruction of eastern North China craton evidenced by seismically imaged lithosphere delamination and Nd isotopes

The North China Craton (NCC) lost its stable craton characteristics in the Mesozoic. How the NCC continues to evolve after the Mesozoic is worth further investigation. Here, we determined high-resolution lithospheric structure of the NCC by joint inversion of body wave arrival times, surface wave dispersion data and receiver functions. The velocity image shows that the NCC has been greatly destructed with very thin lithosphere in the eastern part (~60-70 km). In comparison, beneath the western part, or mainly the Ordos basin, the lithosphere is thicker and is around ~120 km. Beneath the north-south gravity lineament (NSGL), there is a tunnel-shaped low velocity zone with its apex close to the Moho, suggesting the original lithosphere mantle in this part was completely destructed and metasomatized. Several high-velocity bodies are imaged below ~80-90 km in the eastern NCC, which are interpreted as delaminated lithosphere. Based on the depths of these delaminated bodies and geochemical data, we propose they most likely occurred in the Cenozoic. The lithosphere delamination in the Cenozoic is spatially consistent with the heat flow distribution, as it can trigger the upwelling of hot mantle materials. In addition, the velocity image also indicates that the eastern edge of the lithosphere mantle beneath the Ordos basin is under destruction, likely by the sustaining westward mantle flow. Based on the positive and negative εNd values of Cenozoic magma samples in the NCC, it can be further derived that the Cenozoic eastern NCC destruction is jointly controlled by convective mantle flow and lithosphere delamination.