Crustal Propersity From Joint Constraint Of Gravity And Seismic Data And Application In The Eastern China

Crust thickness and Vp/Vs parameters are important parameters describing the structure and material composition of the crust.In addition,reliable crustal thickness can not only be used for crustal evolution and geodynamic analysis,gravity compensation and simulation,but also provide important basic constraints for crustal correction in seismic wave imaging research.This paper proposes an improved method for constraining crustal thickness,Vp/Vs and average P-wave velocity by using receiver function,surface wave dispersion and gravity data.First,the improved method is verified based on two crustal models.The results show that the improved method can not only improve the estimation accuracy of crustal thickness and Vp/Vs,but also give an accurate estimate of the average crustal P-wave velocity.In addition,this paper also applies this method to the analysis of the crustal structure of two permanent stations in South China.The relevant results also confirm the feasibility and reliability of this method in determining the crustal structure estimation.The thesis uses the teleseismic waveform data of 160 broadband seismic stations in the North China Array to study the crustal structure of North China based on the sequential H-? stacking method.Research have shown that the sediment of the North China Basin have thicker sediment,among which the thickness of the sediment in the Jizhong depression zone is the thickest,3-6 km.The crustal thickness in the northeastern part of the North China Craton has obvious lateral changes,and the crustal thickness is between 28 km-49 km.Among them,the North China Basin to the east of the Taihang Mountain and the east side of the Yanshan Orogenic Belt have a small crustal thickness(<34 km),while the central and western parts of the North China Craton have a large range of crustal thickness,ranging from 36-46 km.The average crustal wave velocity ratio in the study area is about 1.65-1.86.Among them,the Yanshan-Taihang orogenic belt Yanqing-Huailai and Yuxian-Lingqiu areas have a relatively high average crustal Vp/Vs(>1.76),which may be related to the partial melting of the crust in this area..Compared with the above areas,the average crustal Vp/Vs in the North China Basin is relatively low,suggesting that the crustal composition in this area is dominated by felsic components.