Investigation On The Crustal Structure In The Southeastern Margin Of The Ordos Block By Receiver Function Analysis

North China Block (NCB) underwent reconstruction through multi-stage tectonic movements, such as the collision of South China Block and North China Block, the Indo-Asian collision and the subduction of the Pacific plate. These tectonic movements have different features, and so the crustal structure in sub-blocks of NCB has distinct characteristics. The study area is in the southeastern margin of the Ordos Block, which is not only a transition zone between NE-NNE striking tectonic zone and E-W striking tectonic zone but also a transition zone between the compression in western China and the extension in eastern China. The detailed crustal structure can provide important information to study geodynamics in this area.We use teleseismic receiver functions to study the crustal thickness and structure along a seismic profile in the southeastern margin of the Ordos Block. Then we use the method of phase-weighted stack, H-κstack, common conversion point stack and common conversion point migrate to stack the receiver functions, and we get the detailed crustal structure in the study area. The result shows Moho's depth gradually decreases towards the southeast, from about 42 km in the Ordos Block to～31 km near the northern margin of the Qinling Orogen. Accordingly, the study region can be divided into four parts:①Beneath the Ordos Block, the Moho is visible and flat at a depth of～40 km. The crustal structure is best characterized by the stable craton crust.②In the Weihe-Shanxi Graben, the Moho is uplifted about～3 km, which may be caused by the upwelling of upper mantle materials.③Under the Xionger-Funiu Mountains, the Moho is flat with a depth between 36～33 km, and it becomes shallower towards the southeast.④In the Hehuai Basin adjacent to the northern margin of the Qinling Orogen, the Moho shows strong lateral variations with a mean depth～31 km, and the crustal structure is very complex, which may reflect complicated tectonic environment here. Otherwise, the Moho is obviously interrupted beneath two stations (hs06 and hs13), which may be influenced by faults near tectonic boundaries.