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We investigated velocity and anisotropic structure of the crust beneath the eastern margin of the Tibetan Plateau to better understand its deformation and evolution mechanism. We performed H‐κ and Pms anisotropy analyses to obtain crustal thickness, Vp/Vs ratio, fast polarization direction, and splitting time from 711 stations, and further conducted quality control using slowness, harmonic and statistical analyses. The Songpan‐Ganzi Block has a large splitting time and a fast polarization direction roughly parallel to the GPS motion and SKS fast direction. It also shows an overall high but complex distribution of Vp/Vs ratio, and large variations in crustal thickness, indicating that crustal deformation is likely caused by crustal shortening and lower crustal flow. The northern Sichuan‐Yunnan Rhombic Block (SYRB) is featured by a thick crust and high Vp/Vs ratio, suggesting that the crust is likely inflated by partial melting lower crustal rocks. The subblock also exhibits a strong azimuthal anisotropy with a splitting time greater than 0.6 s. The fast polarization direction aligns with the nearly N‐S extended direction and rotates clockwise in front of the Emeishan Large Igneous Province (ELIP). The observed anisotropy agrees with aligned amphibole minerals under a simple shear condition, supporting a southward lower crust flow being diverted by the ELIP. Anisotropy measurements on the southern SYRB are less robust and widely scattered, suggesting a deformation mechanism different from the northern SYRB. In addition, the southeastern margin of the Sichuan Basin shows a systematic pattern of crustal anisotropy consistent with a pure shear deformation mechanism. Plain Language Summary: We studied the crustal structure and deformation beneath the eastern edge of the Tibetan Plateau. By analyzing teleseismic data from 727 stations, we measured crust thickness, Vp/Vs ratio, and azimuthal anisotropy using receiver functions. Our findings show a complex crustal behavior pattern in the eastern Tibet margin. In the Songpan‐Ganzi Block, crustal shortening and lower crust flow seem to be causing deformation. The northern Sichuan‐Yunnan Rhombic Block, with its thick crust and high Vp/Vs ratio, appears to be influenced by partial melting of lower crust rocks. And a southward lower crust flow being diverted by the Emeishan Large Igneous Province. The eastern and southern part of this block shows a different pattern, indicating a unique deformation mechanism. Additionally, the southeastern margin of the Sichuan Basin appears to undergo a distinct type of crustal deformation. Key Points: A new crustal model with much more reliable and denser Pms anisotropic measurements is built in the eastern Tibetan MarginSongpan‐Ganzi Block is likely deformed by crustal shortening and lower crustal flowChannel flow may exist in the west low velocity zone (LVZ) while absent at the east LVZ [ABSTRACT FROM AUTHOR]

The Fenhe‐Weihe Rift (FWR) system is one of the most active rift zones in east China, and plays an important role in the reactivation of the North China Craton. In this work, a high‐resolution 3‐D lithospheric S wave velocity model of the FWR is built by joint inversion of receiver functions and ambient noise. Strong correlation between topography and tectonic features is observed at shallow depths. At great depths, strong heterogeneities are observed along the FWR: (1) high‐velocity anomalies emerge beneath the Weihe and Taiyuan basins in the lower crust; (2) two high‐velocity anomalies are imaged in the uppermost mantle beneath the south to central FWR; and (3) two strong large‐scale, low‐velocity zones are observed beneath the north Trans‐North China Oregon: one is at ~60 km and the other one is much larger with a deeper source. Based on the petrologic properties, geochemical analyses, and seismic images obtained in this work, we propose that the rifting mechanisms between the south and north FWR are different. In the south, the rifting could be mainly caused by the passive effects from the uplift of the Tibetan Plateau, while in the north the rifting is due to the combined effects of the asthenosphere upwelling and the counterclockwise rotation of the Ordos block. The uppermost mantle high‐velocity anomalies underneath the south to central part of the FWR could be the remnants of strong ancient cratonic root, and act as mechanical barriers to block the rifting processes between the south and north FWR. Plain Language Summary: A high‐resolution 3‐D crustal and uppermost mantle model of S wave velocity of the Fenhe‐Weihe Rift (FWR) is based on joint inversions of receiver functions and ambient noise. Two high‐velocity bodies are imaged in the uppermost mantle beneath the south to central FWR, while a large‐scale, low‐velocity zone was located beneath the north Trans‐North China Oregon. Passive rifting in the southern FWR is due to the uplift of the Tibetan Plateau, while rifting in the northern FWR is ascribed to the joint effects of the asthenosphere upwelling and propagation of the rifting from the south. Key Points: A high‐resolution 3‐D lithospheric S wave model of the FWR based on joint inversions of receiver functions and ambient noiseTwo high‐velocity bodies in the uppermost mantle beneath south to central FWR and a large‐scale, low‐velocity zone beneath the north TNCODifferent rifting mechanisms between the south and north FWR deciphered by the 3‐D seismic images in this work and previous evidences [ABSTRACT FROM AUTHOR]