南海复蘑菇状地幔低速柱结构及其地幔动力学

The structure of the composite mushroom-shaped mantle plume in the South China Sea and its mantle dynamics

运用高分辨率天然地震面波层析成像和体波层析成像技术,研究东亚西太平洋地区及全球地幔三维速度结构时发现南海地区地幔存在深达2000km以上的巨型复蘑菇状地幔低速柱,结合地质、地球化学和地球物理相关标志,将复蘑菇状地幔低速柱称为南海复蘑菇状地幔柱。本文在论述南海复蘑菇状地幔柱的地质地球物理特征基础上,将地幔柱划分为柱头、柱体、柱尾、幔枝和热点等部分,建立起地幔柱三维几何结构模型,探讨了复蘑菇状地幔柱在南海海盆扩张过程中的主导作用以及欧亚板块、菲律宾海板块和印度洋板块相互作用对南海演化过程的影响。

In the study of the 3 -D velocity structure in the mantle of East Asia, West Pacific Ocean and the globe using the high -resolution tomographical techniques of both natural seismic surface and body wave, the authors discovered a giant composite mushroom-shaped low-velocity mantle plume with the depth of over 2000 km, which, combined with the indicators of geology, geochemistry, and geophysics, is named the South China Sea composite mushroom-shaped mantle plume. This paper describes geological, geochemical, and geophysical features of the plume, divides it into such parts as the tail, the main body, the head, the mantle apophysis, and the basalt hot spot, develops a tentative 3-D geometric structural style for the plume, and discusses the dominant role that the plume and its derived mande dynamics have played in the basin spreading of the South China Sea and the impact of the interaction among the Eurasian, the Philippine, and the Indian-Australian plates on the basin evolution.