High Resolution Crustal and Upper Mantle Velocity Structures in the Northwest Margin of the Songliao Basin: Implications for Volcanic Genesis

Based on observational data from mobile arrays and surrounding fixed stations in the Arxan and Nuomin River regions, this study employed joint inversion of ambient noise and surface waves to obtain a high‐resolution (0.25° × 0.25°) three‐dimensional S‐wave velocity model of the crust and upper mantle. Results indicate incomplete lithospheric delamination along the northwestern margin of the Songliao Basin, with preserved lithospheric fragments in some areas. The associated asthenospheric upwelling is identified as the deep‐source mechanism driving volcanism in Arxan, Nuomin River, and Wudalianchi.