Mantle Dynamics Beneath the Sichuan Basin and Eastern Tibet From Teleseismic Tomography

The cratonic Sichuan Basin is located east of the Tibetan Plateau, and surrounded by mountains that have undergone complex deformation uplift since Cenozoic. Imaging mantle structure important for understanding its formation, to date most models suggest a deep root underlies basin, blocking eastward extrusion lithospheric material beneath Tibet. Here, we obtain detailed upper from teleseismic tomography in region utilizing travel time data earthquakes recorded at 506 seismic stations, including 25 new stations poorly sampled Basin. Contrasting previous models, show southeastward dipping high-velocity anomalies extending ∼150–400 km into We suggest, subduction Yangtze Block occurred Mesozoic may be reactivated Cenozoic, with relatively thin weak lithosphere prone response growth Plateau. A west-dipping anomaly eastern Tibet interpreted as delaminated lithosphere. This delamination accelerate development Xianshuihe fault zone horizontal Beneath East Qinling orogen, plateau not obvious suggesting limited present north