We assemble the continuous waveform data recorded by 571 broadband temporary seismic stations from 2014 to 2015 in the northeastern (NE) margin of the Tibetan plateau and its surrounding regions. Rayleigh and Love wave phase velocity dispersion curves ( = 5–50 s) are obtained by the image transformation technique. Then the phase velocity dispersion data are used to jointly invert the 3-D shear wave velocity (V) and radial anisotropy (ξ) models in the study region with the direct surface wave radial anisotropy tomography (DRadiSurfTomo) method. The ξ is negative and positive in the upper crust and mid-to-lower crust, respectively, indicating that the crustal deformation pattern is depth-dependent. The middle crust beneath the NE margin of the Tibetan plateau generally exhibits positive ξ. Two low-velocity zones (LVZs) are detected beneath the Songpan-Garzê block and the western Qinling orogen as well as the northern Qilian orogen. High-velocity zone (HVZ) and positive ξ are characterized in the mid-to-lower crust beneath both the Alxa block and the Ordos basin. Combining with the previous results, we propose these two blocks, as a whole belonging to a part of the North China Craton (NCC), effectively restrict the northeastward growth of the Tibetan plateau. The uneven crustal deformation along the boundary between the NE margin of the Tibetan plateau and its surrounding regions is likely to be affected by the far-field stress originating from the collision between the Indian and Eurasian plates.

中文翻译：

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直接面波径向各向异性层析成像揭示青藏高原东北缘及周边地区地壳结构

我们汇总了青藏高原东北缘及周边地区571个宽带临时地震台站2014年至2015年记录的连续波形数据。通过图像变换技术获得瑞利波和洛夫波相速度色散曲线（= 5-50 s）。然后利用相速度色散数据通过直接表面波径向各向异性层析成像（DRadiSurfTomo）方法联合反演研究区域的3维剪切波速度（V）和径向各向异性（ψ）模型。上地壳和中下地壳的 χ 分别为负值和正值，表明地壳变形模式与深度相关。青藏高原东北缘以下的中地壳普遍呈现正 Ψ 值。在松潘-甘孜地块和西秦岭造山带以及北祁连造山带下方检测到两个低速区（LVZ）。阿拉善地块和鄂尔多斯盆地下方的中下地壳均具有高速带（HVZ）和正 ε 特征。结合前人研究结果，我们认为这两个区块整体上属于华北克拉通（NCC）的一部分，有效地制约了青藏高原的东北扩展。青藏高原东北缘与周边地区边界上的不均匀地壳变形可能是受到印度板块与欧亚板块碰撞产生的远场应力的影响。