JpGU-AGU Joint Meeting 2017

講演情報

[EE] ポスター発表

セッション記号 S (固体地球科学) » S-IT 地球内部科学・地球惑星テクトニクス

[S-IT30] [EE] Characterizing/contrasting seismic discontinuities in the oceanic and continental lithosphere

2017年5月22日(月) 13:45 〜 15:15 ポスター会場 (国際展示場 7ホール)

コンビーナ:Xuzhang Shen(Lanzhou Insititute of Seismology, China Earthquake Administration)、Younghee Kim(Seoul National University)、Teh-Ru Alex Song(University College London)、Rainer Kind

[SIT30-P06] Lithospheric thinning in the Cathaysia block (South China) from joint inversion of receiver function, surface wave dispersion, and P-wave velocity

*Yangfan Deng1,2Jiangtao Li2Xiaodong Song2,3Xinlei Sun1YuSong Shen4 (1.GIG Guangzhou Institute of Geochemistry, Chinese Academy of Sciences、2.Department of Geology, University of Illinois at Urbana-Champaign、3.School of Geodesy and Geomatics, Wuhan University、4.Earthquake Administration of Guangdong Province)

キーワード:Lithospheric thinning, Joint inversion, South China, Partial melt

Cratons are stable geological blocks, whose thickness is typically more than 200 km. However, the lithosphere in the North China Craton is believed to have been modified since Mesozoic. More recent geochemical studies show that the lithosphere in eastern China has been destructed. Nevertheless, the study of the lithospheric structure in the Cathaysia block (South China) is rare. In this study, we use a new joint inversion method to focus on the lithospheric structure below a dense seismic array in the Cathaysia block, where the P-wave receiver functions, surface wave dispersions, and P-wave velocity are available. The layered S velocity and Vp/Vs ratio are obtained simultaneously. The thin lithospheric thickness (60-70 km) is comparable with the thickness in eastern North China Craton, which provides clear evidence of lithospheric thinning in the Cathaysia block. The low S velocity and high Vp/Vs in the middle crust indicate possible partial crustal melting. The lithospheric thinning and the consequent crustal melting could be possible reason for the widely distributed granitoids in South China.