The Deformational Journey of the Nazca Slab From Seismic Anisotropy

Shubham Agrawal; Caroline M. Eakin; Daniel E. Portner; Emily E. Rodriguez; Susan L. Beck

doi:10.1029/2020GL087398

The Deformational Journey of the Nazca Slab From Seismic Anisotropy

Shubham Agrawal^*, Caroline M. Eakin, Daniel E. Portner, Emily E. Rodriguez, Susan L. Beck

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

5 Citations (Scopus)

Abstract

The Andean subduction zone is an excellent place to study deformation within a subducting slab as a function of depth, owing to the varying and well-resolved geometry of the subducting Nazca slab beneath South America. Here we combine the results of source-side shear wave splitting with the latest regional tomography model to isolate intraslab raypaths and determine the spatial distribution of anisotropy within the Nazca slab. We observe that in the upper mantle, the intraslab anisotropy appears strongest where the slab is most contorted, suggesting a strong link between anisotropy and subduction-related slab deformation. We identify a second source of anisotropy (δt∼ 1 s) within the subducting slab at lower mantle depths (660–800 km). The surrounding mantle and transition zone appear largely isotropic, with deep anisotropy concentrated within the slab as it deforms while entering the higher-viscosity lower mantle.

Original language	English
Article number	e2020GL087398
Journal	Geophysical Research Letters
Volume	47
Issue number	11
DOIs	https://doi.org/10.1029/2020GL087398
Publication status	Published - 16 Jun 2020

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title = "The Deformational Journey of the Nazca Slab From Seismic Anisotropy",

abstract = "The Andean subduction zone is an excellent place to study deformation within a subducting slab as a function of depth, owing to the varying and well-resolved geometry of the subducting Nazca slab beneath South America. Here we combine the results of source-side shear wave splitting with the latest regional tomography model to isolate intraslab raypaths and determine the spatial distribution of anisotropy within the Nazca slab. We observe that in the upper mantle, the intraslab anisotropy appears strongest where the slab is most contorted, suggesting a strong link between anisotropy and subduction-related slab deformation. We identify a second source of anisotropy (δt∼ 1 s) within the subducting slab at lower mantle depths (660–800 km). The surrounding mantle and transition zone appear largely isotropic, with deep anisotropy concentrated within the slab as it deforms while entering the higher-viscosity lower mantle.",

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T1 - The Deformational Journey of the Nazca Slab From Seismic Anisotropy

AU - Agrawal, Shubham

AU - Eakin, Caroline M.

AU - Portner, Daniel E.

AU - Rodriguez, Emily E.

AU - Beck, Susan L.

PY - 2020/6/16

Y1 - 2020/6/16

N2 - The Andean subduction zone is an excellent place to study deformation within a subducting slab as a function of depth, owing to the varying and well-resolved geometry of the subducting Nazca slab beneath South America. Here we combine the results of source-side shear wave splitting with the latest regional tomography model to isolate intraslab raypaths and determine the spatial distribution of anisotropy within the Nazca slab. We observe that in the upper mantle, the intraslab anisotropy appears strongest where the slab is most contorted, suggesting a strong link between anisotropy and subduction-related slab deformation. We identify a second source of anisotropy (δt∼ 1 s) within the subducting slab at lower mantle depths (660–800 km). The surrounding mantle and transition zone appear largely isotropic, with deep anisotropy concentrated within the slab as it deforms while entering the higher-viscosity lower mantle.

AB - The Andean subduction zone is an excellent place to study deformation within a subducting slab as a function of depth, owing to the varying and well-resolved geometry of the subducting Nazca slab beneath South America. Here we combine the results of source-side shear wave splitting with the latest regional tomography model to isolate intraslab raypaths and determine the spatial distribution of anisotropy within the Nazca slab. We observe that in the upper mantle, the intraslab anisotropy appears strongest where the slab is most contorted, suggesting a strong link between anisotropy and subduction-related slab deformation. We identify a second source of anisotropy (δt∼ 1 s) within the subducting slab at lower mantle depths (660–800 km). The surrounding mantle and transition zone appear largely isotropic, with deep anisotropy concentrated within the slab as it deforms while entering the higher-viscosity lower mantle.

KW - Nazca slab

KW - seismic anisotropy

KW - slab anisotropy

KW - slab deformation

KW - source side splitting

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ER -

The Deformational Journey of the Nazca Slab From Seismic Anisotropy

Abstract

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