DOI: 10.1016/j.epsl.2019.115905
论文题名: Mantle flow entrained by the Hindu Kush continental subduction inferred from source-side seismic anisotropy
作者: Peng C.-C. ; Kuo B.-Y. ; Faccenda M. ; Chiao L.-Y.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2020
卷: 530 语种: 英语
中文关键词: continental subduction
; Hindu Kush
; seismic anisotropy
; slab breakoff
; sub-slab mantle
; subduction entrainment
英文关键词: Anisotropy
; Olivine
; Seismology
; Shear waves
; Continental subductions
; Hindu Kush
; Seismic anisotropy
; Slab break-off
; sub-slab mantle
; Shear flow
; A-type rock
; Indian plate
; mantle source
; polarization
; S-wave
; seismic anisotropy
; slab
; subduction zone
; wave splitting
; Hindu Kush
英文摘要: The intermediate-depth seismicity below the Hindu-Kush orogen is thought to mark the Indian-plate subduction with the bottom half of the slab currently breaking off. Unique features of this continental subduction are the near-vertical slab and the roughly stationary convergence boundary. How this subduction affects the mantle flow patterns remains to be understood. In this study we measured source-side shear wave splitting on the S waves from Hindu Kush intraslab events to sample the surrounding mantle. The observed fast polarization directions exhibit a circular pattern around the slab resembling that predicted for the toroidal flow driven by slab rollback. However, the rollback scenario is not favored because it hardly sustains in dynamic models without a considerable retreat of convergence boundary. We propose that the observed pattern is produced by the sub-vertical shear flow entrained by the steep descent of the slab and the ongoing breakoff. This scenario requires the existence of A-type or AG-type olivine fabrics with strong orthorhombic anisotropy in mid- to lower upper mantle, which is consistent with the global models of azimuthal and radial anisotropy. This interpretation circumvents the debate on the cause of trench-parallel anisotropy in some oceanic subduction zones where slab entrainment and rollback may coexist, and supports the notion that orthorhombic anisotropy of olivine may play an important role in shaping mantle anisotropy. © 2019 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165205
Appears in Collections: 气候变化与战略
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作者单位: Institute of Oceanography, National Taiwan University, Taipei, Taiwan; Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan; Dipartimento di Geoscienze, Università di Padova, Padova, Italy
Recommended Citation:
Peng C.-C.,Kuo B.-Y.,Faccenda M.,et al. Mantle flow entrained by the Hindu Kush continental subduction inferred from source-side seismic anisotropy[J]. Earth and Planetary Science Letters,2020-01-01,530