DOI: 10.1016/j.epsl.2021.116911
论文题名: Dual structure of poloidal and toroidal flow under the Cocos subduction zone
作者: Peng C.-C. ; Kuo B.-Y. ; Tan E.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 565 语种: 英语
中文关键词: asthenosphere
; Cocos subduction zone
; mantle flow
; seismic anisotropy
英文关键词: Plates (structural components)
; Seismology
; Anisotropy patterns
; Asthenosphere
; Coco subduction zone
; Lithosphere-asthenosphere boundary
; Mantle flow
; Plate motions
; Poloidal flow
; Seismic anisotropy
; Subduction zones
; Toroidal flow
; Anisotropy
; asthenosphere
; Cocos plate
; seismic anisotropy
; seismology
; slab
; subduction zone
英文摘要: How the underlying mantle responds to the subduction of an oceanic plate remains controversial. Numerical models demonstrate the presence of 3D flow in the sub-slab mantle with a poloidal component induced by slab entrainment and a toroidal component driven by slab rollback. These flows produce plate–motion–parallel and trench-parallel fast directions of seismic anisotropy, respectively, allowing them to be distinguished via the anisotropy pattern. However, seismology studies have so far documented the dominance of either, but not both, type of flow in most subduction zones, evoking debates concerning the flow mechanisms. We employed source-side anisotropy technique to map the sub–slab mantle of the Cocos subduction zone. The observed anisotropy pattern can be best explained by a plate–motion–parallel anisotropy layer, roughly 130 km thick, underlain by a trench-oblique anisotropy regime. We interpret this phenomenon as an entrained poloidal flow transitioning to a rollback–induced toroidal flow modified to suit the regional tectonics. This finding reconciles the current debate over which flow prevails behind a subduction zone. The upper, entrained layer in our model extends below the lithosphere–asthenosphere boundary previously defined in the vicinity of the middle America trench, suggesting strong coupling along the lithosphere–asthenosphere boundary in this region. © 2021 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165627
Appears in Collections: 气候变化与战略
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作者单位: Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
Recommended Citation:
Peng C.-C.,Kuo B.-Y.,Tan E.. Dual structure of poloidal and toroidal flow under the Cocos subduction zone[J]. Earth and Planetary Science Letters,2021-01-01,565