Remnants and fragments of the subducted paleo-Pacific plate:Constraints from geochemistry and geophysics  

作　　者：Xisheng XU Zhouchuan HUANG Dingsheng JIANG Gang ZENG Li-Qun DAI 

机构地区：[1]State Key Laboratory for Mineral Deposits Research,School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,China [2]School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,China

出　　处：《Science China Earth Sciences》2024年第10期3041-3061,共21页中国科学（地球科学英文版）

基　　金：supported by the National Key R&D Program of China (Grant Nos.2022YFF0800404,2022YFF0800402)。

摘　　要：The subduction and rollback of the paleo-Pacific plate during Mesozoic time was the key engine for the evolution of the continental margin in eastern China. It led to lateral accretion of continental crust in Northeast China, lithospheric destruction beneath the North China Craton, and the generation of huge volumes of felsic magmatic rocks in South China. This had a profound influence on deep material cycles and the evolution of epigenetic environmental systems along the continental margin of East Asia. To fully understand the transformation of the dynamic mechanism during the subduction and rollback of the paleoPacific plate, we have attempted to trace the remnants and fragments of the subducted paleo-Pacific plate at great depths. Such remnants in both temporal and spatial dimensions can be tracked by using geochemical and geophysical approaches. Studies of the trace elements, Mg-Zn isotopes and Os-Nd-Hf-Pb-O isotopes in continental basalts from eastern China reveal a significant number of the remnants of subduction of the paleo-Pacific plate, and the initial subduction can be traced back to the Early Jurassic. Large-scale geophysical imaging unveils a multitude of high-velocity anomalies in the lower mantle of East Asia.Notably, many high-velocity bodies, aptly referred to as “slab graveyards”, are nestled at the base of the lower mantle. Numerous isolated high-velocity anomalies are also present in the upper part of the lower mantle, creating conduits for the descent of the subducted slabs into the lower mantle. However, a resolution of the remnants for the subducted slabs within the lower mantle are quite low. Consequently, their impact on the lower mantle's dynamics is yet to be thoroughly investigated. Finally, the presently observed big mantle wedge(BMW) in East Asia has developed through subduction of the Pacific plate in the Cenozoic.However, following the rollback of the paleo-Pacific plate(began at ~145 Ma), a Cretaceous BMW system would also form above the mantle transition zone in East Asia. Th

关 键 词：Paleo-Pacific plate Big mantle wedge Late Mesozoic Remnants and fragments GEOCHEMISTRY GEOPHYSICS 

分 类 号：P534.5[天文地球—古生物学与地层学] P542[天文地球—地质学]