Abstract Phase velocities at periods of 20–143 s are inverted from Rayleigh surface waves recorded at 201 stations of permanent and temporary seismic network deployed in the northern Ordos Block. We obtained the shear-wave velocities in the upper mantle from phase velocities. Our velocity models clearly reveal a striking low-velocity anomaly zone in the upper mantle beneath the northeastern margin of the Ordos Block. The low-velocity zone at periods of 50–100 s extends from the north end of the Luliangshan Mountain to the north border of the western North China craton. The minimum shear-wave velocity is approximately 4.2 km/s and the minimum lithospheric thickness is approximately 80 km in the low-velocity anomaly zone. Our shear-wave velocity results indicate that lithospheric thinning, asthenospheric upwelling and partial melting may occur in the region during the Cenozoic. High temperature and thinned lithosphere may be significant factors that cause partial melting in the asthenospheric mantle. During the Cenozoic, asthenospheric upwelling may be associated with the lithospheric stretching caused by the extension stress in the northeastern margin of the Ordos Block. The extension stress may be contemporaneous with the regional extension of various stages, which is related to the Pacific subduction and the far-field effect of the Indian-Eurasian collision in the Cenozoic.

中文翻译：

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鄂尔多斯地块东北缘软流圈上升流：瑞利面波层析成像的约束

摘要 鄂尔多斯区块北部部署的永久和临时地震台网 201 个台站记录的瑞利面波记录了 20-143 s 周期的相速度。我们从相速度获得了上地幔中的横波速度。我们的速度模型清楚地揭示了鄂尔多斯地块东北缘下上地幔中一个引人注目的低速异常带。50～100 s周期的低速带从吕梁山北端一直延伸到华北克拉通西部的北缘。在低速异常区，最小横波速度约为 4.2 km/s，最小岩石圈厚度约为 80 km。我们的横波速度结果表明岩石圈变薄，该地区在新生代可能发生软流圈上升流和部分熔融。高温和变薄的岩石圈可能是导致软流圈地幔部分熔化的重要因素。新生代软流圈上升流可能与鄂尔多斯地块东北缘伸展应力引起的岩石圈伸展有关。伸展应力可能与各个阶段的区域伸展同时发生，这与太平洋俯冲和新生代印欧碰撞远场效应有关。软流圈上升流可能与鄂尔多斯地块东北缘伸展应力引起的岩石圈伸展有关。伸展应力可能与各个阶段的区域伸展同时发生，这与太平洋俯冲和新生代印欧碰撞远场效应有关。软流圈上升流可能与鄂尔多斯地块东北缘伸展应力引起的岩石圈伸展有关。伸展应力可能与各个阶段的区域伸展同时发生，这与太平洋俯冲和新生代印欧碰撞远场效应有关。