Crust and upper mantle electrical structure and tectonic deformation of the northeastern margin of the Tibetan Plateau and the adjacent Ordos Block

In order to obtain the crust and upper mantle electrical structure of the northeastern margin of the Tibetan Plateau and the adjacent Ordos Block and to further study the tectonic style and deformation of the survey area, a magnetotelluric (MT) sounding profile has been completed. The profile contains 91 sites and goes approximately east-westward from Longxi county, Gansu to Huangling county, Shanxi. Dimensionality analysis demonstrated that the MT data can be interpreted using two-dimensional (2D) approaches. 2D inversions were carried out after data processing, qualitative analysis and strike analysis. The final resistivity model derived from the inversions revealed the crust and upper mantle electrical structures along the profile. According to the electrical structures, the profile can be divided into three tectonic units: the North Qilian Orogenic Belt, the Liupanshan Belt and the Ordos Block, which is consistent with the regional geology settings. The electrical structure of North Qilian Orogenic Belt reveals that the growth of the Tibetan Plateau is a tectonic superimposing and reforming process on the existing Trench Arc-Basin system. The structure of the crust and upper mantle of Liupanshan Belt is complicated; The Ordos Block is characterized by the four-layer electrical structures with resistive upper crust and high conductive layer(HCL). The interior of the Ordos Block is stable while the southern part experienced distinct material and structural reconstruction associated with the upwelling of the upper mantle.