Seismic Velocity Structure and Composition of the Continental Crust of Eastern China  

作　　者：WANGYang CAOJiamin ZHUJieshou 

机构地区：[1]GuangzhouInstituteofGeochemistry,ChineseAcademyofSciences,Guangzhou,Guangdong510640 [2]SchoolofEarthSciencesandResources,ChinaUniversityofGeosciences,Beijing100083 [3]DepartmentofGeophysics,ChengduUniversityofTechnology,Chengdu,Sichuan610059

出　　处：《Acta Geologica Sinica(English Edition)》2004年第1期291-297,共7页地质学报（英文版）

基　　金：supported by grants from the National Natural Science Foundation of China(No.40104003);China Post-doctoral Science Foundation;the Chinese Academy of Sciences K.C.Wong Post-doctoral Research Award

摘　　要：On the basis of a one-by-one latitude-longitude grid three-dimensional seismic velocity model, the crustal P-wave velocity structure in eastern China (105-125°E and 18-41°N) is obtained, and a set of geotherms for each grid is established for P-T correction on P-wave velocities. The average depths of sub-crustal layers and their average P-wave velocities of 18 tectonic units in eastern China are exhibited. Our result presents a 32-34 km thick crust beneath eastern China, which is thinner than previous studies, with an average velocity of 6.54 km/s, corresponding to a 5 kg/m3 variation in crustal mean density. The thicker upper but thinner middle and lower crust results in a lower average seismic velocity of eastern China. An intermediate crustal composition with a SiO2 content of 59.7 wt% has been estimated. However, there exists a significant lateral variation in the crustal structures among the tectonic units of eastern China. The structure and composition features of some regions in eastern China indicate that extension has played an important role in the continental crust evolution of eastern China.On the basis of a one-by-one latitude-longitude grid three-dimensional seismic velocity model, the crustal P-wave velocity structure in eastern China (105-125°E and 18-41°N) is obtained, and a set of geotherms for each grid is established for P-T correction on P-wave velocities. The average depths of sub-crustal layers and their average P-wave velocities of 18 tectonic units in eastern China are exhibited. Our result presents a 32-34 km thick crust beneath eastern China, which is thinner than previous studies, with an average velocity of 6.54 km/s, corresponding to a 5 kg/m3 variation in crustal mean density. The thicker upper but thinner middle and lower crust results in a lower average seismic velocity of eastern China. An intermediate crustal composition with a SiO2 content of 59.7 wt% has been estimated. However, there exists a significant lateral variation in the crustal structures among the tectonic units of eastern China. The structure and composition features of some regions in eastern China indicate that extension has played an important role in the continental crust evolution of eastern China.

关 键 词：crustal composition seismic velocity structure GEOTHERM DENSITY eastern China 

分 类 号：P315.2[天文地球—地震学] P591.1[天文地球—固体地球物理学]