Small‐ and Medium‐Wavelength Dynamic Topography and Active Mantle Flow in Eastern China

Abstract Eastern China has undergone significant intracontinental extension and intraplate magmatism since the Cenozoic, but related geodynamic mechanisms remain controversial. Here we use calculations of Residual Topography (RT) and Dynamic Topography (DT) as diagnostic indicators of active mantle flow in the region. The latest crustal structure is adopted to calculate new RT estimates, and 3D spherical mantle convection experiments based on a high‐resolution seismic velocity model are constructed to estimate the DT across Eastern China. Comparative analyses reveal several insights: (a) RT and DT are correlated at medium wavelength, showing a low‐west and high‐east pattern. High positive values dominate Northeastern China, Cathaysia Block, and the South China Sea (SCS), whereas low negative values concentrate in the Ordos, Sichuan, and Songliao basins; (b) Positive DT in Northeastern China correlates with Quaternary intraplate volcanism, linked to mantle upwelling induced by the Pacific Plate subduction. Conversely, negative DT in Songliao Basin and Eastern North China Block (ENCB) reflects mantle downwelling associated with lithospheric delamination; (c) The stable Ordos and Sichuan basins display pronounced negative RT and DT, indicative of dense cratonic roots, while the elevated topography in the ENCB and Cathaysia Block is driven by mantle upwelling from the Pacific‐Philippine plate subduction; (d) High positive RT and DT in the SCS correspond to widespread recent magmatism, primarily fueled by large‐scale mantle upwelling beneath the SCS. The findings suggest that mantle convection caused by surrounding subduction systems plays a significant role in Cenozoic intraplate volcanism and lithospheric evolution in Eastern China.