Upper mantle discontinuity structure beneath the Hindu Kush:Insights into dynamics of the Indian slab  

作　　者：Qinghui CUI Yuanze ZHOU Yuan GAO Lijun LIU 

机构地区：[1]Key Laboratory of Earthquake Prediction,Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China [2]College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China [3]Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [4]Department of Geology,University of Illinois at Urbana-Champaign,Urbana IL 61801,USA

出　　处：《Science China Earth Sciences》2025年第3期720-729,共10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. 42074101, 42374113, 42074103);the Central Public-interest Scientific Institution Basal Research Fund (Grant Nos. CEAIEF20220201, CEAIEF20230204);the Science & Technology Fundamental Resources Investigation Program (Grant No. 2023FY101500);the TianHe Qingsuo Special Fund Project。

摘　　要：Upper mantle discontinuities play an important role in slab dynamics and mantle responses in the subduction zones.Despite increasing numbers of seismological observations in the Hindu Kush, fine structures of mantle discontinuities still remain less explored, highlighting less understood interactions of the Indian slab and discontinuities. Here we collected a large dataset of several dense seismic networks/arrays, extracted near-source SdP waves in P-wave codas using the N-th root slant stackings, and then systematically imaged upper mantle discontinuities around the Indian slab beneath Hindu Kush. In comparison with the IASP91 model, we confirmed an abrupt topographic transition of the 410-km discontinuity(410) from uplifts of up to 41 km to depressions of less than 20 km near the slab edge and a slightly depressed 660-km discontinuity(660) with depths of 660 to 668 km below the slab front, as well as a fluctuating 300-km discontinuity(300) with depths of 264 to 337 km. We suggest that the 410 is elevated by the Indian slab due to the interior coldness, and deepened near the slab edge by the hot upwelling slab-entrained mantle that escapes below the slab bottom. Based on a depressed 410 inside the Indian slab and a 660with slight depressions below the slab, we infer that the subducted Indian slab currently stretches into the upper MTZ. Moreover,we interpret the fluctuant 300 as the coesite to stishovite phase transition in the subduction-zone mantle enriched in the eclogite.When considered alongside other studies, our results can provide more insights into the dynamics of the Indian slab and mantle responses.

关 键 词：Hindu Kush subduction zone Upper mantle discontinuities Indian slab Hot slab-entrained mantle N-th root slant stacking 

分 类 号：P548[天文地球—构造地质学]