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

查看全文 作　　者：[1]WANGYang;[2]CAOJiamin;[3]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)》索引2004年第78卷第1期,共7页 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 Pwave 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：地壳成分 地震速率构造 等温线 中国东部 密度