High-resolution lithosphere structure beneath the North China Craton from teleseismic Rayleigh wave tomography

The North China Craton (NCC) is one of the Archean Cratons on the Earth and traditionally divided into two major Archean blocks, the eastern and western NCC (ENCC and WNCC). The assembly of two blocks along the central NCC (CNCC) was confined to Paleoproterozoic and related to the assembly of the supercontinent Columbia. The ENCC was proved to have experienced intensive reactivation and destruction in Phanerozoic time, while the lithosphere of the CNCC and WNCC was locally modified and reactivated. In this study, we conduct Rayleigh-wave tomography using the teleseismic data collected from both the China National Seismic Network and two broadband sub-array of the North China Interior Structure Project to provide deep structural constraints on the lithospheric modification and reactivation of the NCC. In the CNCC and WNCC, the resultant 3-D Shear wave velocity structure indicates the presence of a high-velocity and thick (> 200 km) cratonic root beneath the Ordos Block. Surrounding the Ordos Block, the lithosphere is local modified and reactivated mainly along the mechanically weak zones, indicating low-velocity features. In contrast, low velocity anomalies prevail in the lithosphere of the ENCC, reflecting the widespread and intensive lithospheric reactivation. Combined with the geological and geochemical evidences, the distinct structural variations from the ENCC to the CNCC and WNCC may imply two tectonic regimes and different geodynamic processes during the Phanerozoic evolution of the craton. We acknowledge the financial support by National Natural Science Foundation of China (Grants 90814002, 90914011).