Nature, Source and Composition of Volcanic Ash in Surficial Sediments Around the Zhongsha Islands

Volcanic detrital sediments are a unique indicator for reconstructing the petrogenetie evolution of submarine volcanic terrains. Volcanic ash in surficial sediments around the Zhongsha Islands includes three kinds of volcanogenic detritus, i.e., brown volcanic glass, colorless volcanic glass and volcanic scoria. The major element characteristics show that bimodal volcanic activity may have taken place in the northern margin of the South China Sea, with brown volcanic glass and colorless volcanic glass repre-senting the maric end-member and felsie end-member, respectively. Fractional crystallization is the main process for magma evolu-tion. The nature of the volcanic activity implies that the origin of volcanic activity was related to extensional tectonic settings, which is corresponding to an extensional geodynamie setting in the Xisha Trench, and supports the notion, which is based on geophysical data and petrology, that there may exist a mantle plume around the Hainan Island.

作 者： YAN Quanshu SHI Xuefa WANG Xinyu   作者單位： YAN Quanshu,SHI Xuefa(Key Laboratory of Marine Sedimentology and Environment Geology, State Oceanic Administration, Qingdao 266100, P R. China)

WANG Xinyu(Guangxi Institute of Geological Survey, Nanning 530023, P. R. China) 

刊 名： 中國海洋大學學報（英文版）  ISTIC 英文刊名： JOURNAL OF OCEAN UNIVERSITY OF CHINA  年，卷(期)： 2008 7(2)  分類號： P7  關鍵詞： volcanic glass   bimodal volcanic activity   tectonic setting   the South China Sea  

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