| In this paper,the general situation of regional geology and geotectonics in Ordos block and Shanxi rift area is briefly described,and the research results of many scholars on the structure of crust and upper mantle in Ordos block and Shanxi rift area are reviewed.On the basis of these results,suggestions and development prospects for further research in this area are put forward.The research work in this study area is to extract 16745 high-quality radial Pwave receiver functions from the teleseismic data recorded by 150 three-component broadband mobile stations in North China from November 2016 to January 2019 by using the time domain iterative deconvolution method.The distribution of crustal thickness and wave velocity ratio structure in Ordos block and Shanxi rift area is obtained by H-? stacking method,and the distribution of Poisson's ratio in the study area is calculated by the optimal value of wave velocity ratio,and then the material composition of the crust in the study area is discussed;The Moho surface morphology of Ordos block and Shanxi rift zone is obtained by the Common conversion point stacking method of receiver function,and the structure of crust and upper mantle in this area is studied in combination with other existing geological and geophysical data,as well as the regional structural characteristics in the study area.In addition,the formation process of Shanxi fault depression zone is preliminarily talked in combination with the regional structural characteristics.The main research results are as follows:(1)The thickness of the crust in the study area is between 30-47 km,and the variation range is large,and there is a horizontal variation from west to East,and there is a mirror relationship between the depth of Moho surface and the altitude of terrain;Compared with the thickness of Ordos block and Taihang uplift on both sides,the thickness of the crust of Ordos block is thinner,and the thickness of the crust of Ordos block is obviously thicker than that of Luliang Mountain Area and Shanxi rift;The analysis is the reflection of the shallow effect of North China Craton failure in the two tectonic units.(2)The Moho surface in the lower part of the Luliang Mountain area,which borders the Northeast Ordos block and the Shanxi rift,is about 3km deep,and the Poisson's ratio in this area is high,which indicates that there may be a low velocity body in the lower crust of this area.It is analyzed that the magma activity in the Datong volcanic area controls the formation and tectonic activity of Shanxi rift to some extent,and the mantle plume formed by the uplift of the upper mantle results in the low velocity characteristics of the region.(3)In Linfen basin of Shanxi Rift and Lingshi and Huozhou areas between Taiyuan Basin and Linfen basin,there is mantle uplifting.It is speculated that the pull-out stress caused by the interaction between plates causes mantle upwelling,crust thinning and lithosphere being stretched,which makes the surface sink to form fault depression belt.(4)In the west of 111 ° E of the study area,the distribution of Poisson's ratio in the crust is relatively uniform,but it is not uniform at the junction of Ordos block and Shanxi rift.There is a high Poisson's ratio distribution in Luliang Mountain Area in the east of Ordos block,which reflects that there is a low-speed body in the lower crust of this area.The Poisson's ratio under Shanxi rift is higher than that in the mountains on both sides,which is presumed to be upwelling of material in the upper mantle.(5)The Poisson's ratio of the crust beneath the stations in the area north of 38 ° N is large,while the Poisson's ratio in the area south of 38 ° N is low.It is speculated that the partial melting of the crust in the area north of 38 ° N shows low velocity characteristics,and the crust structure in the area south of 38 ° N still maintains some structural characteristics of stable crust. |
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