Making continental crust:The sanukitoid connection

作     者：Yoshiyuki TATSUMI 

作者机构：Institute for Research on Earth Evolution (IFREE) Japan Agency for Marine-Earth Science and Technology (JAMSTEC) Yokosuka 237-0061 Japan 

出 版 物：《Chinese Science Bulletin》 (CHINESE SCIENCE BULLETIN)

年 卷 期：2008年第53卷第11期

页      面：1620-1633页

核心收录：

学科分类：070801[理学-固体地球物理学] 07[理学] 0708[理学-地球物理学] 

基　　金：Grant-in-Aid for Creative Scientific Research of Japan (Grant No. 19GS0211) 

主　　题：赞岐状岩 大陆壳 地质学 地质运动 

摘      要：The average continental crust possesses intermediate compositions that typify arc magmatism and as a result it is believed to have been created at ancient convergent plate boundaries. One possible mechanism for intermediate continental crust formation is the direct production of andesitic melts in the upper mantle. Sanukitoids, which characterize the Setouchi volcanic belt, SW Japan, include un-usually high-Mg andesites (HMA). They were generated by slab melting and subsequent melt-mantle interactions under unusual tectonic settings such as where warm lithosphere subducts into hot upper mantle. Such conditions would have existed in the Archean. Hydrous HMA magmas are likely to have solidified within the crust to form HMA plutons, which were then remelted to produce differentiated sanukitoids. At present, generation and differentiation of HMA magmas may be taking place in the Izu-Bonin-Mariana arc-trench system (IBM), because (1) HMA magmatism characterizes the initial stages of the IBM evolution and (2) the IBM middle crust exhibits Vp identical to that of the bulk conti-nental crust. Vp estimates for plutonic rocks with HMA compositions support this. However tonalitic composition for middle-crust-forming rocks cannot be ruled out, suggesting an alternative possibility that the continental crust has been created by differentiation of mantle-derived basaltic magmas.