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Mantle flow geometry from ridge to trench beneath the Gorda–Juan de Fuca plate system

Abstract

Tectonic plates are underlain by a low-viscosity mantle layer, the asthenosphere. Asthenospheric flow may be induced by the overriding plate or by deeper mantle convection1. Shear strain due to this flow can be inferred using the directional dependence of seismic wave speeds—seismic anisotropy. However, isolation of asthenospheric signals is challenging; most seismometers are located on continents, whose complex structure influences the seismic waves en route to the surface. The Cascadia Initiative, an offshore seismometer deployment in the US Pacific Northwest, offers the opportunity to analyse seismic data recorded on simpler oceanic lithosphere2. Here we use measurements of seismic anisotropy across the Juan de Fuca and Gorda plates to reconstruct patterns of asthenospheric mantle shear flow from the Juan de Fuca mid-ocean ridge to the Cascadia subduction zone trench. We find that the direction of fastest seismic wave motion rotates with increasing distance from the mid-ocean ridge to become aligned with the direction of motion of the Juan de Fuca Plate, implying that this plate influences mantle flow. In contrast, asthenospheric mantle flow beneath the Gorda Plate does not align with Gorda Plate motion and instead aligns with the neighbouring Pacific Plate motion. These results show that asthenospheric flow beneath the small, slow-moving Gorda Plate is controlled largely by advection due to the much larger, faster-moving Pacific Plate.

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Figure 1: Stacked splitting results determined by this study (red bars) and previous work (black bars; from refs 4,28).
Figure 2: Two distinct patterns in the variation of FSDs with distance from the trench.
Figure 3: Two-dimensional modelling to simulate mantle flow below the Gorda Plate as induced by motion of the Pacific Plate.

References

  1. Conrad, C., Behn, M. & Silver, P. Global mantle flow and the development of seismic anisotropy: Differences between the oceanic and continental upper mantle. J. Geophys. Res. 112, B07317 (2007).

    Article  Google Scholar 

  2. Toomey, D. et al. The Cascadia initiative: A sea change in seismological studies of subduction zones. Oceanography 27, 138–150 (2014).

    Article  Google Scholar 

  3. Riddihough, R. Recent movements of the Juan de Fuca plate system. J. Geophys. Res. 89, 6980–6994 (1984).

    Article  Google Scholar 

  4. Eakin, C. et al. Seismic anisotropy beneath Cascadia and the Mendocino triple junction: Interaction of the subducting slab with mantle flow. Earth Planet Sci. Lett. 297, 627–632 (2010).

    Article  Google Scholar 

  5. Currie, C. et al. Shear wave anisotropy beneath the Cascadia subduction zone and western North American craton. Geophys. J. Int. 157, 341–353 (2004).

    Article  Google Scholar 

  6. Long, M. & Silver, P. The subduction zone flow field from seismic anisotropy: A global view. Science 319, 315–318 (2008).

    Article  Google Scholar 

  7. Silver, G. & Chan, W. Shear wave splitting and subcontinental mantle deformation. J. Geophys. Res. 96, 16429–16454 (1991).

    Article  Google Scholar 

  8. Nicolas, A. & Christensen, N. in Composition, Structure and Dynamics of the Lithosphere-Asthenosphere System (eds Fuchs, K. & Froidevaux, C.) 111–123 (Geodynamics Series 16, American Geophysical Union, 1987).

    Book  Google Scholar 

  9. Karato, S., Katayama, I. & Skemer, P. Geodynamic significance of seismic anisotropy of the upper mantle: New insights from laboratory studies. Ann. Rev. Earth Planet. Sci. 36, 59–95 (2008).

    Article  Google Scholar 

  10. Song, T. & Kawakatsu, H. Subduction of oceanic asthenosphere: Evidence from sub-slab seismic anisotropy. Geophys. Res. Lett. 39, L17301 (2012).

    Google Scholar 

  11. Heesemann, M. et al. Ocean Networks Canada: From geohazards research laboratories to Smart Ocean Systems. Oceanography 27, 151–153 (2014).

    Article  Google Scholar 

  12. Bell, S., Forsyth, D. & Ruan, Y. Removing noise from the vertical component records of ocean-bottom seismometers: Results from year one of the Cascadia Initiative. Bull. Seismol. Soc. Am. 105, 300–313 (2014).

    Article  Google Scholar 

  13. Webb, S. Broadband seismology and noise under the ocean. Rev. Geophys. 36, 105–142 (1998).

    Article  Google Scholar 

  14. Lodewyk, J. & Sumy, D. Cascadia Amphibious Array Ocean Bottom Seismograph Horizontal Component Orientations (OBSIP Management Office, 2014); http://www.obsip.org/experiments/experiment-list/2011/cascadia.

    Google Scholar 

  15. Wolfe, C. & Solomon, S. Shear-wave splitting and implications for mantle flow beneath the MELT region of the East Pacific Rise. Science 280, 1230–1232 (1998).

    Article  Google Scholar 

  16. Fontaine, F. et al. Upper-mantle flow beneath French Polynesia from shear wave splitting. Geophys. J. Int. 170, 1262–1288 (2007).

    Article  Google Scholar 

  17. Zandt, G. & Humphreys, E. Toroidal mantle flow through the western US slab window. Geology 36, 295–298 (2008).

    Article  Google Scholar 

  18. Obrebski, M. et al. Slab-plume interaction beneath the Pacific Northwest. Geophys. Res. Lett. 37, L14305 (2010).

    Article  Google Scholar 

  19. Nishimura, C. & Forsyth, D. The anisotropic structure of the upper mantle in the Pacific. Geophys. J. Int. 96, 203–229 (1989).

    Article  Google Scholar 

  20. Kendall, J. et al. Magma-assisted rifting in Ethiopia. Nature 433, 146–148 (2005).

    Article  Google Scholar 

  21. Blackman, D. & Kendall, J. Sensitivity of teleseismic body waves to mineral texture and melt in the mantle beneath a mid-ocean ridge. Phil. Trans. R. Soc. Lond. A. 355, 217–231 (1997).

    Article  Google Scholar 

  22. Gripp, A. & Gordon, R. Young tracks of hotspots and current plate velocities. Geophys. J. Int. 150, 321–361 (2002).

    Article  Google Scholar 

  23. Debayle, E. & Ricard, Y. Seismic observations of large-scale deformation at the bottom of fast-moving plates. Earth Planet. Sci. Lett. 376, 165–177 (2013).

    Article  Google Scholar 

  24. Chaytor, J. et al. Active deformation of the Gorda plate: Constraining deformation models with new geophysical data. Geology 32, 353–356 (2004).

    Article  Google Scholar 

  25. Hager, B. H. & O’Connell, R. J. A simple global model of plate dynamics and mantle convection. J. Geophys. Res. 86, 4843–4867 (1981).

    Article  Google Scholar 

  26. Fjeldskaar, W. Viscosity and thickness of the asthenosphere detected from the Fennoscandian uplift. Earth Planet. Sci. Lett. 126, 399–410 (1994).

    Article  Google Scholar 

  27. Wessel, P. & Smith, W. New, improved version of Generic Mapping Tools released. EOS Trans. Am. Geophys. Union 79, 579 (1998).

    Article  Google Scholar 

  28. Wüstefeld, A. et al. Identifying global seismic anisotropy patterns by correlating shear-wave splitting and surface-wave data. Phys. Earth Planet. Int. 176, 198–212 (2009).

    Article  Google Scholar 

  29. Porritt, R., Allen, R. & Pollitz, F. Seismic imaging east of the Rocky Mountains with USArray. Earth Planet. Sci. Lett. 402, 16–25 (2014).

    Article  Google Scholar 

  30. Hayes, G., Wald, D. & Johnson, R. Slab1.0: A three-dimensional model of global subduction zone geometries. J. Geophys. Res. 117, B01302 (2012).

    Article  Google Scholar 

  31. Wüstefeld, A. et al. SplitLab: A shear-wave splitting environment in Matlab. Comp. Geosci. 34, 515–528 (2008).

    Article  Google Scholar 

  32. Wüstefeld, A. et al. A strategy for automated analysis of passive microseismic data to image seismic anisotropy and fracture characteristics. Geophys. Prospect. 58, 755–773 (2010).

    Article  Google Scholar 

  33. Bowman, J. & Ando, M. Shear-wave splitting in the upper-mantle wedge above the Tonga subduction zone. Geophys. J. Int. 88, 25–41 (1987).

    Article  Google Scholar 

  34. Wüstefeld, A. & Bokelmann, G. Null detection in shear-wave splitting measurements. Bull. Seism. Soc. Am. 97, 1204–1211 (2007).

    Article  Google Scholar 

  35. Wolfe, C. & Silver, P. Seismic anisotropy of oceanic upper mantle: Shear wave splitting methodologies and observations. J. Geophys. Res. 103, 749–771 (1998).

    Article  Google Scholar 

  36. Stachnik, J. et al. Determination of New Zealand ocean bottom seismometer orientation via Rayleigh-wave polarization. Seism. Res. Lett. 83, 704–713 (2012).

    Article  Google Scholar 

  37. Tian, X. et al. SKS splitting measurements with horizontal component misalignment. Geophys. J. Int. 185, 329–340 (2011).

    Article  Google Scholar 

  38. Richards, M. et al. Role of a low-viscosity zone in stabilizing plate tectonics: Implications for comparative terrestrial planetology. Geochem. Geophys. Geosyst. 2, 1026 (2001).

    Article  Google Scholar 

  39. Nettles, M. & Dziewński, A. Radially anisotropic shear velocity structure of the upper mantle globally and beneath North America. Geophys. J. Int. 113, B02303 (2008).

    Google Scholar 

  40. Paulson, A. & Richards, M. On the resolution of radial viscosity structure in modeling long-wavelength postglacial rebound data. Geophys. J. Int. 179, 1516–1526 (2009).

    Article  Google Scholar 

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Acknowledgements

Support for this work was provided by the National Science Foundation (OCE-1139701) to R.M.-S. and R.M.A. The data used in this research were provided by instruments from the Ocean Bottom Seismograph Instrument Pool (http://www.obsip.org), which is funded by the National Science Foundation under cooperative agreement OCE-1112722. The work benefited from discussions with J. Lodewyk, A. Frassetto and C. Eakin. GMT (Wessel and Smith27) and MATLAB were used to create the figures.

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This study was carried out and written up by R.M.-S., under supervision of R.M.A. I.D.B. assisted with data analysis and helped write the paper. E.T. and M.A.R. provided advice and minor modifications to the text.

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Correspondence to Robert Martin-Short.

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Martin-Short, R., Allen, R., Bastow, I. et al. Mantle flow geometry from ridge to trench beneath the Gorda–Juan de Fuca plate system. Nature Geosci 8, 965–968 (2015). https://doi.org/10.1038/ngeo2569

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