气候变化领域集成服务门户(CCPortal): Dual structure of poloidal and toroidal flow under the Cocos subduction zone

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DOI	10.1016/j.epsl.2021.116911
	Dual structure of poloidal and toroidal flow under the Cocos subduction zone
	Peng C.-C.; Kuo B.-Y.; Tan E.
发表日期	2021
ISSN	0012821X
卷号	565
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.
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
语种	英语
来源期刊	Earth and Planetary Science Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/203249
作者单位	Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
推荐引用方式 GB/T 7714	Peng C.-C.,Kuo B.-Y.,Tan E.. Dual structure of poloidal and toroidal flow under the Cocos subduction zone[J],2021,565.
APA	Peng C.-C.,Kuo B.-Y.,&Tan E..(2021).Dual structure of poloidal and toroidal flow under the Cocos subduction zone.Earth and Planetary Science Letters,565.
MLA	Peng C.-C.,et al."Dual structure of poloidal and toroidal flow under the Cocos subduction zone".Earth and Planetary Science Letters 565(2021).