Global seismic tomography reveals remnants of subducted Tethyan oceanic slabs in the deep mantle  

作　　者：Zewei WANG Jiashun HU Xueyang BAO Chunquan YU Yingjie YANG Xiaofei CHEN 

机构地区：[1]Guangdong Provincial Key Laboratoryof Geophysical High-resolution Imaging Technology,Southern University of Science and Technology Shenzhen 518055,China [2]Department of Earth and Space Sciences,Southern University of Science and Technology,Shenzhen 518055,China

出　　处：《Science China Earth Sciences》2023年第12期2751-2769,共19页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos.92155307,U1901602,42274058,42174106);the Shenzhen Science and Technology Program (Grant No.KQTD20170810111725321);the Guangdong Provincial Key Laboratory of Geophysical High-resolution Imaging Technology (Grant No.2022B1212010002)。

摘　　要：The Tethyan evolution depicts the continuous process of landmasses separating from the Gondwana continent in the south,drifting northwards,and subsequently colliding with the continents in the north over the past 500 million years.In this process,the Tethyan oceans that formed between the landmass and the southern or northern continents underwent growth,evolution,and eventual closure with the early Cenozoic India-Eurasia collision.However,the Tethyan lithosphere did not disappear but rather continued to evolve after entering into the deep Earth.The current position,morphology,and volume of the subducted Tethyan oceanic slabs in the deep mantle record the latest moment of this continuous evolution,providing critical constraints for Tethyan studies.This paper summarizes and analyzes the results of global-scale whole-mantle seismic tomography in the past nearly two decades,revealing a northwest-southeast seismically high-velocity anomaly,which is linearly distributed at depths of 1000–2000 km beneath the Tethyan realm and referred to as the Tethyan anomaly.By searching for an optimal linear combination of previous global seismic tomographic models to best match the known subducted slabs in the upper mantle,we observe that the Tethyan anomaly extends approximately 8700 km in length and 2600 km in width,exhibiting a parallel structure with northern and southern branches.Combining geological records of oceanic subduction initiation and previous geodynamic studies,this study suggests that the main body of the Tethyan anomaly represents the remnants of the subducted Neo-Tethyan oceanic slabs,which subducted from the Late Jurassic to the early Cenozoic.The northern branch consists of subducted slabs from the Neo-Tethys beneath the southern margin of Eurasia,while the southern branch likely reflects the intra-oceanic subducted slabs of Neo-Tethys during the Cretaceous.The western portion of the Tethyan anomaly may reflect remnants of Paleo-Tethys,while the eastern portion,towards India and the Bay of Bengal,shows signs o

关 键 词：Global seismic tomography Tethyan evolution Oceanic slabs Lower-mantle structure High-velocity anomaly 

分 类 号：P542.5[天文地球—构造地质学]