Geophysical Research Letters

Directions of seismic anisotropy in laboratory models of mantle plumes

Authors

  • K. A. Druken,

    Corresponding author
    1. Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, D. C., USA
    2. Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
    • Corresponding author: K. A. Druken, Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA. (kdruken@dtm.ciw.edu)

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  • C. Kincaid,

    1. Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
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  • R. W. Griffiths

    1. Research School of Earth Sciences, Australian National University, Canberra, ACT, Australia
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Abstract

[1] A recent expansion in global seismic anisotropy data provides important new insights about the style of mantle convection. Interpretations of these geophysical measurements rely on complex relationships between mineral physics, seismology, and mantle dynamics. We report on 3-D laboratory experiments using finite strain markers evolving in time-dependent, viscous flow fields to quantify the range in expected anisotropy patterns within buoyant plumes surfacing in a variety of tectonic settings. A surprising result is that laboratory proxies for the olivine fast axis overwhelmingly align tangential to radial outflow in plumes well before reaching the surface. These remarkably robust, and ancient, anisotropy patterns evolve differently in stagnant, translational, and divergent plate tectonic settings and are essentially orthogonal to patterns typically referenced when prospecting for plume signals in seismic data. Results suggest a fundamental change in the mineral physics-seismology-circulation relationship used in accepting or rejecting a plume model.

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