A Study Of Crust-mantle Transition Zone Of Different Tectonic Blocks In Sichuan-yunnan

In this paper,we study the crust-mantle transition zone of different tectonic blocks in the Sichuan-Yunnan region,and the Sichuan-Yunnan region is located in the southeastern margin of the Qinghai-Tibet Plateau.It is a key area to study the lateral escape of the plateau material.The structural characteristics of the crust-mantle transition zone can be studied.The tectonic evolution of the area provides evidence of seismology.In this paper,the frequency distribution characteristics of the fine structure of the crust-mantle transition zone beneath the station carried by the Pms converted wave are studied in detail.The structure of the crust-mantle transition zone corresponding to the waveform feature is used to show the different crust-mantle transition zone The method of calculating the thickness range of the characteristic frequency.Based on the seismic records with similar seismic locations,the receiving function of different Gaussian coefficients of each station in Sichuan and Yunnan areas is extracted,and the thickness of the transition zone between shell and mantle and the velocity structure of crust and mantle transition zone are obtained.The fine structure of crust and mantle boundary Based on the telephoto waveform data recorded by fixed seismic stations,the crossover transition zone structure of different blocks in the study area is studied by using the frequency division feature and Hk method of the receiver function Ps.The main results are as follows:1.The transitional zone of the crust-mantle beneath the stable Yangtze block is relatively simple,mainly composed of a first-order interdiffusion,the thickness of which is between 0.86 km and 1.44 km,and the crust-mantle transition zone of the Yangtze block is first-Reflecting its structural stability;The thickness of the transition zone is 1.8km-3.4km,and the crust-mantle transition zone in the Songpan Ganzi area is high and low-speed inter-phase structure,suggesting that the tectonic activity is strong.In the Songpan Ganzi area,The thickness of the transition zone is 1.1-3.6km,and the crust-mantle transition zone of Baoshan and Lanping blocks is characterized by velocity gradient structure,and its activity Weaker than Songpan Ganzi area.As the Sichuan-Yunnan region is located in the southeastern margin of the Qinghai-Tibet Plateau,is the main area of the plateau material escape,the Qinghai-Tibet Plateau uplift,making the Sichuan-Yunnan region of the block structure is strong,complex structure.According to the results of this study,it can be found that the activity of the North and South Songpan Ganzi block near the Qinghai-Tibet Plateau is relatively strong,and the activity of the Baoshan Landrace from the Qinghai-Tibet Plateau is obviously weaker than that of the Songpan Ganzi area,while the stable lithosphere of the Yangtze plate is quite hard,Stable structure.