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 

作者机构：State Key Laboratory for Mineral Deposits Research School of Earth Sciences and Engineering Nanjing University School of Earth and Space Sciences University of Science and Technology of China 

出 版 物：《Science China Earth Sciences》 (中国科学:地球科学(英文版))

年 卷 期：2024年第67卷第10期

页      面：3041-3061页

核心收录：

学科分类：070904[理学-构造地质学] 070903[理学-古生物学与地层学(含：古人类学)] 0709[理学-地质学] 07[理学] 

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

主　　题：Paleo-Pacific plate Big mantle wedge Late Mesozoic Remnants and fragments Geochemistry Geophysics 

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 ***, 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 ***, following the rollback of the paleo-Pacific plate(began at ～145 Ma), a Cretaceous BMW system would also form above