Exotic origin of the Chinese continental shelf: new insights into the tectonic evolution of the western Pacific and eastern China since the Mesozoic  

作　　者：Yaoling Niu Yi Liu Qiqi Xue Fengli Shao Shuo Chen Meng Duan Pengyuan Guo Hongmei Gong Yan Hu Zhenxing Hu Juanjuan Kong Jiyong Li Jinju Liu Pu Sun Wenli Sun Lei Ye Yuanyuan Xiao Yu Zhang 

机构地区：[1]Institute of Oceanology, Chinese Academy of Sciences [2]Department of Earth Sciences, Durham University [3]School of Earth Science and Resources, China University of Geosciences [4]Institute of Deep Sea Science and Engineering, Chinese Academy of Sciences [5]School of Earth Sciences, Lanzhou University

出　　处：《Science Bulletin》2015年第18期1598-1616,共19页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(41130314,91014003);Chinese Academy of Sciences Innovation(Y42217101L),grants from Regional and Local Authorities(Shandong Province and City of Qingdao);supported by National Oceanography Laboratory in Qingdao;supported by the National Natural Science Foundation of China(NSFC)

摘　　要：The effect of paleo-Pacific subduction on the geological evolution of the western Pacific and continental China is likely complex. Nevertheless, our analysis of the distribution of Mesozoic granitoids in the eastern continental China in space and time has led us to an interesting conclusion： The basement of the continental shelf beneath East and South China Seas may actually be of exotic origin geologically unrelated to the continental lithosphere of eastern China. By accepting the notion that the Jurassic- Cretaceous granitoids in the region are genetically associated with western Pacific subduction and the concept that subduction may cease to continue only if the trench is being jammed, then the termination of the granitoid magmatism throughout the vast region at -88±2 Ma manifests the likelihood of ＂sudden＂, or shortly beforehand （- 100 Ma）, trench jam of the Mesozoic western Pacific subduction. Trench jam happens if the incoming ＂plate＂ or portion of the plate contains a sizeable mass that is too buoyant to subduct. The best candidate for such a buoyant and unsubductable mass is either an oceanic plateau or a micro-continent. We hypothesize that the basement of the Chinese continental shelf represents such an exotic, buoyant and unsubductable mass, rather than seaward extension of the continental lithosphere of eastern China. The locus of the jammed trench （i.e., the suture） is predictably located on the shelf in the vicinity of, and parallel to, the arc-curved coastal line of the southeast continental China. It is not straightforward to locate the locus in the northern section of the East China Sea shelf because of the more recent （〈20 Ma） tectonic re-organization associated with the opening of the Sea of Japan. We predict that the trench jam at - 100 Ma led to the re-orientation of the Pacific plate motion in the course of NNW direction as inferred from the age-progressive Emperor Seamount Chain of Hawaiian hotspot origin （its oldest unsubdued Meiji and Detroit seamounts are -82 MThe effect of paleo-Pacific subduction on the geological evolution of the western Pacific and continental China is likely complex. Nevertheless, our analysis of the distribution of Mesozoic granitoids in the eastern continental China in space and time has led us to an interesting conclusion: The basement of the continental shelf beneath East and South China Seas may actually be of exotic origin geologically unrelated to the continental lithosphere of eastern China. By accepting the notion that the Jurassic–Cretaceous granitoids in the region are genetically associated with western Pacific subduction and the concept that subduction may cease to continue only if the trench is being jammed, then the termination of the granitoidmagmatism throughout the vast region at *88 ± 2 Ma manifests the likelihood of ‘‘sudden'', or shortly beforehand(*100 Ma), trench jam of the Mesozoic western Pacific subduction. Trench jam happens if the incoming‘‘plate'' or portion of the plate contains a sizeable mass that is too buoyant to subduct. The best candidate for such a buoyant and unsubductable mass is either an oceanic plateau or a micro-continent. We hypothesize that the basement of the Chinese continental shelf represents such an exotic, buoyant and unsubductable mass, rather than seaward extension of the continental lithosphere of eastern China. The locus of the jammed trench(i.e., the suture) is predictably located on the shelf in the vicinity of, and parallel to, the arc-curved coastal line of the southeast continental China. It is not straightforward to locate the locus in the northern section of the East China Sea shelf because of the more recent(\20 Ma) tectonic re-organization associated with the opening of the Sea of Japan. We predict that the trench jam at *100 Ma led to the re-orientation of the Pacific plate motion in the course of NNW direction as inferred from the age-progressive Emperor Seamount Chain of Hawaiian hotspot origin(its oldest unsubdued Meiji and Detroit seamounts are *82 Ma),making the bound

关 键 词：Mesozoic granitoids in eastern ChinaExotic origin of Chinese continental shelf Trenchjam Transform plate boundary Basal hydrationweakening Lithosphere thinning Cratondestruction Mantle hydrous melting Crustalmelting Plate tectonics South China Sea 

分 类 号：P736[天文地球—海洋地质]