The Yinchuan Graben (YG) is situated in the transitional area between the Tibetan Plateau, Ordos Block (OB) and Alxa Block (AB). The dynamic mechanism of the YG is controversial because of its unique tectonic environment. This study used a broadband magnetotelluric profile constrained by high-density point spacing to reliably obtain the deep electrical structure across the Helanshan Orogenic Belt and YG and to discuss the dynamic mechanism of the YG. The main research results are as follows. 1) Our profile and previous seismic profiles show a low-resistivity and low-velocity body in the deep YG, which extends upward and cuts through the bottom boundary of the upper crust, and all results indicate that this body may be the result of partial melting due to upwelling mantle material. 2) Our profile also shows a high-resistivity anomaly in the middle-lower crust of the Helanshan orogenic belt, which can be interpreted as intrusive rocks formed by the emplacement of partially melted materials. 3) The Helanshan east piedmont fault dips eastward and intersects with the Yellow River fault at the depth of 20 km, and the typical structure of the intersection may be the seismogenic structure of the Pingluo Ms8.0 earthquake. 4) The evolution of the YG may have been controlled by various dynamic mechanisms, and the initial formation of the YG may have resulted from the upwelling mantle material beneath the northern OB; the evolution of the YG since 10 Ma may also have been affected by lateral mantle flow from the Tibetan Plateau to the gap between the OB and AB.

银川地堑（YG）位于青藏高原、鄂尔多斯地块（OB）和阿拉善地块（AB）之间的过渡地带。由于其独特的构造环境，YG的动力机制存在争议。本研究使用受高密度点间距约束的宽带大地电磁剖面可靠地获得贺兰山造山带和YG的深部电结构，并讨论YG的动力学机制。主要研究成果如下。1) 我们的剖面和以往的地震剖面显示，YG 深部有一个低阻低速体，向上延伸并切穿上地壳底部边界，所有结果表明该体可能是部分由于上涌的地幔物质而熔化。2）我们的剖面也显示贺兰山造山带中下地壳存在高阻异常，可以解释为部分熔融物质侵位形成的侵入岩。3）贺兰山东山前断裂向东倾斜，在20km深度与黄河断裂相交，交汇处的典型构造可能是平罗Ms8.0地震的发震构造。4) YG 的演化可能受到多种动力机制的控制，YG 的初始形成可能是由 OB 北部的上涌地幔物质引起的；YG 自 10 Ma 以来的演化也可能受到从青藏高原到 OB 和 AB 间隙的侧向地幔流的影响。可以解释为侵入岩是由部分熔化的材料就位形成的。3）贺兰山东山前断层向东倾斜，在20km深度与黄河断层相交，相交的典型构造可能是平罗Ms8.0地震的发震构造。4) YG 的演化可能受到多种动力机制的控制，YG 的初始形成可能是由 OB 北部的上涌地幔物质引起的；YG 自 10 Ma 以来的演化也可能受到从青藏高原到 OB 和 AB 间隙的侧向地幔流的影响。可以解释为侵入岩是由部分熔化的材料就位形成的。3）贺兰山东山前断层向东倾斜，在20km深度与黄河断层相交，相交的典型构造可能是平罗Ms8.0地震的发震构造。4) YG 的演化可能受到多种动力机制的控制，YG 的初始形成可能是由 OB 北部的上涌地幔物质引起的；YG 自 10 Ma 以来的演化也可能受到从青藏高原到 OB 和 AB 间隙的侧向地幔流的影响。交叉口的典型构造可能是平罗Ms8.0地震的发震构造。4) YG 的演化可能受到多种动力机制的控制，YG 的初始形成可能是由 OB 北部的上涌地幔物质引起的；YG 自 10 Ma 以来的演化也可能受到从青藏高原到 OB 和 AB 间隙的侧向地幔流的影响。交叉口的典型构造可能是平罗Ms8.0地震的发震构造。4) YG 的演化可能受到多种动力机制的控制，YG 的初始形成可能是由 OB 北部的上涌地幔物质引起的；YG 自 10 Ma 以来的演化也可能受到从青藏高原到 OB 和 AB 间隙的侧向地幔流的影响。