Aseismic Deep Slab and Mantle Flow Beneath Alaska: Insight From Anisotropic Tomography

Tao Gou, Dapeng Zhao, Zhouchuan Huang, Liangshu Wang

研究成果: Article査読

25 被引用数 (Scopus)

抄録

We present high-resolution 3-D images of P wave velocity (Vp), azimuthal anisotropy (AAN), and radial anisotropy (RAN) down to 900-km depth beneath Alaska obtained by inverting a large number of high-quality arrival time data from local earthquakes and teleseismic events simultaneously. Our results show that the high-Vp Pacific slab has subducted down to 450- to 500-km depths. A prominent slab gap is revealed at depths of 65–120 km near the Wrangell volcanic field, which is likely a slab tear acting as a channel that provides ascending mantle materials to generate magmas feeding the surface volcanoes. In the back-arc mantle wedge near the eastern slab edge, the AAN exhibits trench-parallel fast-velocity directions (FVDs), which may reflect along-strike mantle flow. The FVDs in the subducting Pacific slab are nearly east-west, which may indicate fossil anisotropy formed at the mid-ocean ridge. A negative RAN is revealed within the subducting slab, which may be caused by the fast plate subduction with a steep dip angle. Trench-normal FVDs of the AAN are revealed in the mantle below the Pacific slab, which may reflect mantle flow entrained by the subducting slab. A positive RAN is revealed in the mantle beneath the Yakutat slab, indicating that its shallow subduction flattens the mantle flow below the slab to be subhorizontal. Along-strike FVDs of the AAN around the eastern slab edge may indicate the edge-induced toroidal mantle flow.

本文言語English
ページ(範囲)1700-1724
ページ数25
ジャーナルJournal of Geophysical Research: Solid Earth
124
2
DOI
出版ステータスPublished - 2019 2

ASJC Scopus subject areas

  • 地球物理学
  • 地球化学および岩石学
  • 地球惑星科学(その他)
  • 宇宙惑星科学

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