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通过对青藏高原东边缘及其附近地区石棉-乐山剖面大地电磁资料的研究发现,青藏高原东边缘带和四川地块的电性结构有明显差别,东部的四川地块地壳总体电阻率大,西部的青藏高原东边缘带地壳总体电阻率小.西部地壳分为上中下3层,中地壳为厚约10～15km的低阻层,电阻率最小达3～10Ωm,推测它含有较低黏滞度的部分熔融和(或)含盐流体,易于变形和流动,是青藏高原东边缘带向东南方向挤出作用下形成的“管流”层.它使上地壳和下地壳解耦,上地壳高阻的脆性层以左旋走滑和逆冲的断层运动为主,地表抬升,地震主要发生在上地壳内.低阻层把鲜水河-安宁河深大断裂带截成上下两段.地壳上、中、下层各自厚度的横向变化,综合产生了青藏高原东边缘带地壳厚度西部厚、东部薄、地形西部高、东部低的过渡带.
Through the study on the geomagnetic data of the asbestos-Leshan profile at the eastern edge of the Tibetan Plateau and its vicinity, it is found that there is a clear difference in the electrical structure between the eastern margin of the Qinghai-Tibet Plateau and the Sichuan block. The crustal resistivity of the Sichuan block in the east is large, The total resistivity of the crust in the east margin of the Qinghai-Tibet Plateau is small.The western crust is divided into upper and lower three layers, the middle crust is a low resistance layer with a thickness of about 10-15 km, and the resistivity is as low as 3 ~ 10Ωm, presumably it contains low viscosity Degree of partial melting and / or salt-containing fluid, easy to deform and flow, is formed by the extrusion of the eastern margin of the Qinghai-Tibet Plate with the “tube flow ” layer.It decouples the upper crust and the lower crust, The upper crustal high-resistivity brittle layer is dominated by left-lateral strike-slip and thrust faults and the surface is uplifted, and the earthquakes mainly occur in the upper crust. The low resistivity layer separates the Xianshuihe-Anninghe deep fault zone into upper and lower segments The lateral variation of the thickness of the upper, middle and lower crust of the crust comprehensively produced the transitional zone with the crustal thickness at the east and the west of the Qinghai-Tibet Plateau being thick in the west, thin in the east, high in the west and low in the east.