Broad plumes rooted at the base of the Earth's mantle beneath major hotspots

Abstract

Plumes of hot upwelling rock rooted in the deep mantle have been proposed as a possible origin of hotspot volcanoes, but this idea is the subject of vigorous debate1,2. On the basis of geodynamic computations, plumes of purely thermal origin should comprise thin tails, only several hundred kilometres wide3, and be difficult to detect using standard seismic tomography techniques. Here we describe the use of a whole-mantle seismic imaging technique—combining accurate wavefield computations with information contained in whole seismic waveforms4—that reveals the presence of broad (not thin), quasi-vertical conduits beneath many prominent hotspots. These conduits extend from the core–mantle boundary to about 1,000 kilometres below Earth’s surface, where some are deflected horizontally, as though entrained into more vigorous upper-mantle circulation. At the base of the mantle, these conduits are rooted in patches of greatly reduced shear velocity that, in the case of Hawaii, Iceland and Samoa, correspond to the locations of known large ultralow-velocity zones5,6,7. This correspondence clearly establishes a continuous connection between such zones and mantle plumes. We also show that the imaged conduits are robustly broader than classical thermal plume tails, suggesting that they are long-lived8, and may have a thermochemical origin9,10,11. Their vertical orientation suggests very sluggish background circulation below depths of 1,000 kilometres. Our results should provide constraints on studies of viscosity layering of Earth’s mantle and guide further research into thermochemical convection.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Figure 1: Whole-mantle depth cross-sections of relative shear-velocity variations in model SEMUCB-WM14, in the vicinity of major hotspots.
Figure 2: Three-dimensional rendering of shear-wave-velocity structure in the Pacific Superswell region.
Figure 3: Hawaii, Iceland, St Helena and the African superplume.
Figure 4: Locations of plumes detected in the lower mantle in model SEMUCB-WM14.

References

  1. 1

    Morgan, W. J. Convection plumes in the lower mantle. Nature 230, 42–43 (1971)

    ADS  Article  Google Scholar 

  2. 2

    Anderson, D. L. Scoring hotspots: the plume and plate paradigms. Geol. Soc. Special Papers 388, 31–54 (2005)

    Google Scholar 

  3. 3

    Campbell, I. H. & Griffiths, R. W. Implications of mantle plume structure for the evolution of flood basalts. Earth Planet. Sci. Lett. 99, 79–93 (1990)

    ADS  CAS  Article  Google Scholar 

  4. 4

    French, S. W. & Romanowicz, B. A. Whole-mantle radially anisotropic shear velocity structure from spectral-element waveform tomography. Geophys. J. Int. 199, 1303–1327 (2014)

    ADS  Article  Google Scholar 

  5. 5

    Cottaar, S. & Romanowicz, B. An unusually large ULVZ at the base of the mantle near Hawaii. Earth Planet. Sci. Lett. 355–356, 213–222 (2012)

    ADS  Article  Google Scholar 

  6. 6

    Helmberger, D. V., Wen, L. & Ding, X. Seismic evidence that the source of the Iceland hotspot lies at the core-mantle boundary. Nature 396, 251–255 (1998)

    ADS  CAS  Article  Google Scholar 

  7. 7

    Thorne, M. S., Garnero, E. J., Jahnke, G., Igel, H. & McNamara, A. Mega ultra low velocity zone and mantle flow. Earth Planet. Sci. Lett. 364, 59–67 (2013)

    ADS  CAS  Article  Google Scholar 

  8. 8

    Jellinek, A. M. & Manga, M. The influence of a chemical boundary layer on the fixity, spacing and lifetime of mantle plumes. Nature 418, 760–763 (2002)

    ADS  CAS  Article  Google Scholar 

  9. 9

    Farnetani, C. G. Excess temperature of mantle plumes: the role of chemical stratification across D″. Geophys. Res. Lett. 24, 1583–1586 (1997)

    ADS  CAS  Article  Google Scholar 

  10. 10

    Lin, S.-C. & van Keken, P. E. Dynamics of thermochemical plumes: 2. Complexity of plume structures and its implications for mapping mantle plumes. Geochem. Geophys. Geosyst. 7, Q03003 (2006)

    ADS  Article  Google Scholar 

  11. 11

    Kumagai, I., Davaille, A., Kurita, K. & Stutzmann, E. Mantle plumes: thin, fat, successful or failing? Constraints to explain hot spot volcanism through time and space. Geophys. Res. Lett. 35, L16301 (2008)

    ADS  Article  Google Scholar 

  12. 12

    Thorne, M. S., Garnero, E. J. & Grand, S. P. Geographic correlation between hot spots and deep mantle lateral shear-wave velocity gradients. Phys. Earth Planet. Inter. 146, 47–63 (2004)

    ADS  Article  Google Scholar 

  13. 13

    McNamara, A. K., Garnero, E. J. & Rost, S. Tracking deep mantle reservoirs with ultra-low velocity zones. Earth Planet. Sci. Lett. 299, 1–9 (2010)

    ADS  CAS  Article  Google Scholar 

  14. 14

    Davaille, A. & Limare, A. in Treatise on Geophysics Vol. 7 (ed. Bercovici, D. ) 89–156 (Elsevier, 2007)

    Google Scholar 

  15. 15

    Nolet, G. & Dahlen, F. A. Wavefront healing and the evolution of seismic delay times. J. Geophys. Res. 105, 19043–19054 (2000)

    ADS  Article  Google Scholar 

  16. 16

    Zhao, D. Global tomographic images of mantle plumes and subducting slabs: insight into deep earth dynamics. Phys. Earth Planet. Inter. 146, 3–34 (2004)

    ADS  Article  Google Scholar 

  17. 17

    Montelli, R. et al. Finite-frequency tomography reveals a variety of plumes in the mantle. Science 303, 338–343 (2004)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Suetsugu, D. et al. South Pacific mantle plumes imaged by seismic observation on islands and seafloor. Geochem. Geophys. Geosyst. 10, Q11014 (2009)

    ADS  Article  Google Scholar 

  19. 19

    Boschi, L., Becker, T. W. & Steinberger, B. On the statistical significance of correlations between synthetic mantle plumes and tomographic models. Phys. Earth Planet. Inter. 167, 230–238 (2008)

    ADS  Article  Google Scholar 

  20. 20

    Capdeville, Y., Chaljub, E., Vilotte, J. P. & Montagner, J. P. Coupling the spectral element method with a modal solution for elastic wave propagation in global earth models. Geophys. J. Int. 152, 34–67 (2003)

    ADS  Article  Google Scholar 

  21. 21

    French, S. W., Lekic, V. & Romanowicz, B. Waveform tomography reveals channeled flow at the base of the oceanic asthenosphere. Science 342, 227–230 (2013)

    ADS  CAS  Article  Google Scholar 

  22. 22

    Li, X. et al. Mapping the Hawaiian plume conduit with converted seismic waves. Nature 405, 939–941 (2000)

    ADS  Google Scholar 

  23. 23

    Wolfe, C. J. et al. Mantle P-wave velocity structure beneath the Hawaiian hotspot. Earth Planet. Sci. Lett. 303, 267–280 (2011)

    ADS  CAS  Article  Google Scholar 

  24. 24

    Laske, G. et al. Asymmetric shallow mantle structure beneath the Hawaiian Swell—evidence from Rayleigh waves recorded by the PLUME network. Geophys. J. Int. 187, 1725–1742 (2011)

    ADS  Article  Google Scholar 

  25. 25

    Albers, M. & Christensen, U. The excess temperature of plumes rising from the core mantle boundary. Geophys. Res. Lett. 23, 3567–3570 (1996)

    ADS  Article  Google Scholar 

  26. 26

    Courtillot, V., Davaille, A., Besse, J. & Stutzmann, E. Three distinct types of hotspots in the Earth’s mantle. Earth Planet. Sci. Lett. 205, 295–308 (2003)

    ADS  CAS  Article  Google Scholar 

  27. 27

    Steinberger, B. Plumes in a convecting mantle: models and observations for individual hotspots. J. Geophys. Res. 105, 11127–11152 (2000)

    ADS  Article  Google Scholar 

  28. 28

    Nataf, H. C. & VanDecar, J. Seismological detection of a mantle plume? Nature 364, 115–120 (1993)

    ADS  Article  Google Scholar 

  29. 29

    Su, W. J., Woodward, R. L. & Dziewonski, A. M. Degree 12 model of shear velocity heterogeneity in the mantle. J. Geophys. Res. 99, 6945–6980 (1994)

    ADS  Article  Google Scholar 

  30. 30

    Fukao, Y. & Obayashi, M. Subducted slabs stagnant above, penetrating through, and trapped below the 660 km discontinuity. J. Geophys. Res. 118, 1–19 (2013)

    Article  Google Scholar 

  31. 31

    Forte, A. M. & Mitrovica, J. K. Deep mantle high viscosity flow and thermochemical structure inferred from seismic and geodetic data. Nature 410, 1049–1056 (2001)

    ADS  CAS  Article  Google Scholar 

  32. 32

    Marquardt, H. & Miyagi, L. Slab stagnation in the shallow lower mantle due to an increase in mantle viscosity. Nature Geosci. 8, 311–314 (2015)

    ADS  CAS  Article  Google Scholar 

  33. 33

    Nolet, G., Karato, S. I. & Montelli, R. Plume fluxes from seismic tomography. Earth Planet. Sci. Lett. 248, 685–699 (2006)

    ADS  CAS  Article  Google Scholar 

  34. 34

    Lekić, V. & Romanowicz, B. Inferring upper-mantle structure by full waveform tomography with the spectral element method. Geophys. J. Int. 185, 799–831 (2011)

    ADS  Article  Google Scholar 

  35. 35

    Komatitsch, D. & Vilotte, J. P. The spectral element method: an efficient tool to simulate the seismic response of 2D and 3D geological structures. Bull. Seismol. Soc. Am. 88, 368–393 (1998)

    MATH  Google Scholar 

  36. 36

    Li, X.-D. & Romanowicz, B. Comparison of global waveform inversions with and without considering cross-branch modal coupling. Geophys. J. Int. 121, 695–709 (1995)

    ADS  Article  Google Scholar 

  37. 37

    French, S. W., Zheng, Y., Romanowicz, B. & Yelick, K. Parallel Hessian assembly for seismic waveform inversion using global updates. In Proc. 29th IEEE Int. ‘Parallel and Distributed Processing’ Symp. (IEEE, http://dx.doi.org/10.1109/IPDPS.2015.58 (2015)

    Google Scholar 

  38. 38

    Mégnin, C. & Romanowicz, B. The three-dimensional shear velocity structure of the mantle from the inversion of body, surface and higher-mode waveforms. Geophys. J. Int. 143, 709–728 (2000)

    ADS  Article  Google Scholar 

  39. 39

    Durek, J. J. & Ekstrom, G. A radial model of anelasticity consistent with long-period surface-wave attenuation. Bull. Seismol. Soc. Am. 86, 144–158 (1996)

    Google Scholar 

  40. 40

    Wang, Z. & Dahlen, F. A. Spherical-spline parametrization of three-dimensional earth models. Geophys. Res. Lett. 22, 3099–3102 (1995)

    ADS  Article  Google Scholar 

  41. 41

    Tarantola, A. Inverse Problem Theory and Models for Model Parameter Estimation (Society for Industrial and Applied Mathematics (SIAM), 2005)

    Google Scholar 

  42. 42

    Lévêque, J., Rivera, L. & Wittlinger, G. On the use of the checker-board test to assess the resolution of tomographic inversions. Geophys. J. Int. 115, 313–318 (1993)

    ADS  Article  Google Scholar 

  43. 43

    Macpherson, C. G., Hilton, D. R., Sinton, J. M., Poreda, R. J. & Craig, H. High 3He/4He ratios in the Manus backarc basin: implications for mantle mixing and the origin of plumes in the western Pacific Ocean. Geology 26, 1007–1010 (1998)

    ADS  CAS  Article  Google Scholar 

  44. 44

    Ritsema, J., van Heijst, H. J. & Woodhouse, J. H. Complex shear wave velocity structure imaged beneath Africa and Iceland. Science 286, 1925–1928 (1999)

    CAS  Article  Google Scholar 

  45. 45

    Kreemer, C. Absolute plate motions constrained by shear wave splitting orientations with implications for hot spot motions and mantle flow. J. Geophys. Res. 114, B10405 (2009)

    ADS  Article  Google Scholar 

  46. 46

    Ritsema, J., Deuss, A., Van Heijst, H. & Woodhouse, J. S40RTS: a degree-40 shear-velocity model for the mantle from new Rayleigh wave dispersion, teleseismic traveltime and normal-mode splitting function measurements. Geophys. J. Int. 184, 1223–1236 (2011)

    ADS  Article  Google Scholar 

  47. 47

    Montelli, R., Nolet, G., Dahlen, F. A. & Masters, G. A catalogue of deep mantle plumes: new results from finite-frequency tomography. Geochem. Geophys. Geosyst. 7, Q11007 (2006)

    ADS  Article  Google Scholar 

  48. 48

    Houser, C., Masters, G., Shearer, P. & Laske, G. Shear and compressional velocity models of the mantle from cluster analysis of long-period waveforms. Geophys. J. Int. 174, 195–212 (2008)

    ADS  Article  Google Scholar 

  49. 49

    Simmons, N. A., Forte, A. M., Boschi, L. & Grand, S. P. GyPSuM: a joint tomographic model of mantle density and seismic wave speeds. J. Geophys. Res. 115, B12310 (2010)

    ADS  Article  Google Scholar 

  50. 50

    Stixrude, L. & Lithgow-Bertelloni, C. Mineralogy and elasticity of the oceanic upper mantle: Origin of the low-velocity zone. J. Geophys. Res. 110, B03204 (2005)

    ADS  Article  Google Scholar 

  51. 51

    Karato, S.-I. Deformation of Earth Materials: Introduction to the Rheology of the Solid Earth (Cambridge Univ. Press., 2008)

    Google Scholar 

Download references

Acknowledgements

We thank the IRIS Data Management Center for providing the waveform data used in this study. This study was supported by an NSF Graduate Research Fellowship to S.W.F., NSF grant EAR-1417229, and ERC Advanced Grant WAVETOMO. Computations were performed at the National Energy Research Scientific Computing Center, supported by the US Department of Energy Office of Science (contract DE-AC02-05CH11231).

Author information

Affiliations

Authors

Contributions

B.R. and S.W.F. collaborated in developing the concept of this paper. B.R. wrote the first draft, which was jointly finalized through successive iterations. S.W.F. is responsible for most of the technical aspects of this work, including the realization of most of the figures, with input from B.R. on figure design. B.R. is responsible for Fig. 4 and Extended Data Table 1.

Corresponding author

Correspondence to Barbara Romanowicz.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 Intermodel comparisons.

These figures correspond to the cross-sections in Fig. 1c and d, oriented normal to the direction of Pacific absolute plate motion45. As in Fig. 1, sections are indicated in the inset maps, while white and purple circles indicate position along section and orientation. Shown are relative shear-wave velocity (Vs) anomalies in models SEMUCB-WM1 (this study), S40RTS (ref. 46), PRI-S05 (ref. 47), HMSL-S06 (ref. 48) and GyPSuM (ref. 49), each plotted with respect to its own one-dimensional reference (where the latter notion is well defined: see for example ref. 48; where defined, the one-dimensional reference is often the global average). Panels ae correspond to the MacDonald-hotspot-centred view of Fig. 1d; panels fj correspond to the Pitcairn-centred view of Fig. 1c. This comparison shows that the five models are broadly compatible with each other at long wavelengths. However, in the lower mantle, the MacDonald and Pitcairn plumes are much more clearly defined as vertical conduits in SEMUCB-WM1, and stand out as the strongest and most continuous low-velocity features in the lower mantle in these cross-sections (which span almost half of Earth’s circumference).

Extended Data Figure 2 Intermodel comparisons.

These comparisons correspond to Fig. 1e, f, presented in a similar manner to those in Extended Data Fig. 1. We again find that models SEMUCB-WM1, S40RTS, PRI-S05, HMSL-S06 and GyPSuM are broadly compatible with each other at long wavelengths. However, in the lower mantle, the plumes beneath both Cape Verde and Canary are more clearly defined as well isolated vertical conduits in SEMUCB-WM1. Furthermore, while we do observe some degree of correspondence between the two plumes imaged in SEMUCB-WM1 and some anomalies also present in PRI-S05 or HMSL (for example, the plume root at the CMB beneath Cape Verde, or the lateral translation of the plume around 1,000 km beneath Canary), the unambiguously columnar nature of the anomalies imaged in SEMUCB-WM1 stands in stark contrast.

Extended Data Figure 3 Inter-model comparisons.

These cross-sections are similar to those in Extended Data Fig. 1, but now feature two approximately orthogonal sections through the African LLSVP: ae, traversing from northwest to southeast; fj, traversing from southwest to northeast. The African LLSVP is more massive, and therefore better resolved in S40RTS, PRI-S05, HMSL-S06 and GyPSuM than are other plumes. As in Extended Data Fig. 2, we again note some degree of similarity between SEMUCB-WM1 (a), PRI-S05 (c) and HMSL-S06 (d) below the Cape Verde plume.

Extended Data Figure 4 Linear resolution analysis, examining recovery of synthetic whole- and partial-mantle plumes of width 1,000 km beneath Hawaii and Iceland.

Synthetic plume input models, shown in the upper row of panels, have a peak amplitude of −2% and a cosine-cap lateral amplitude profile (thus, the effective width above 1% anomaly strength is only 500 km). In addition to looking at a whole-mantle plume, we also examine recovery of plumes truncated at successively greater depths (1,000 km, 1,500 km and 2,000 km) to assess vertical smearing. Artefacts seen above the truncation depth in the synthetic input models are due to slight aliasing phenomena associated with the radial b-spline basis functions used to parameterize our model. We find that all four input plumes are recovered quite well beneath both Hawaii (centre row), with relatively denser data coverage, and Iceland (bottom row), with comparatively sparser coverage—although there is a slight difference in amplitude recovery beneath the two (maximum amplitude recovered is shown for each panel). Importantly, we see no evidence of lateral (or, in the case of the truncated plumes, radial) smearing, nor do we detect significant gaps in recovery. However, recovered amplitude does vary as a function of depth, with comparatively weaker, although still satisfactory, recovery in the less well sampled mid-mantle (of the order of half of the input anomaly strength). For a more thorough discussion of the caveats implied by linear resolution analysis in the context of our inversion, as well as additional resolution tests, see ref. 4.

Extended Data Figure 5 Linear resolution analysis.

Similar to that in Extended Data Fig. 4. This analysis again features whole- and partial-mantle plumes of peak strength −2%, but now of width 600 km (meaning the effective width above 1% anomaly strength is only 300 km). We again find that the synthetic input plumes are recovered quite well, with no evidence of lateral or radial smearing, as well as no gaps in recovery. At the same time, we find that recovered amplitude is poorer than for the larger, 1,000-km-width plumes, in some cases recovering amplitudes of the order of one-quarter of the input, and we note that there is again a slight disparity in amplitude recovery between Hawaii and Iceland. Furthermore, we note that tests using synthetic plumes at or below widths of 600 km push the limits of the spherical-spline lateral basis functions used in our model—particularly in the upper mantle, where the inter-spline absolute distance is larger (although the angular distance remains constant).

Extended Data Figure 6 Further linear resolution analysis.

This analysis is of a 400-km-width plume-like conduit extending from the CMB to 1,000-km depth, with a similar lateral profile (a cosine cap) and maximum amplitude (−2%) as the test structures in Extended Data Figs 4 and 5. The inherent limits of our spherical spline basis prohibit us from representing this narrow conduit with sufficient fidelity for the purposes of this test above 1,000 km. Upper panel, conduit-like input structure; lower panel, output structure resulting from resolution test. We observe that the output structure is at least 800 km in width, but is also significantly weaker than the input, exhibiting a maximum amplitude of −0.6% near its base, while only reaching −0.3 or −0.4% elsewhere in its core. As such, we can infer that the input-structure amplitudes would need to be increased by at least 10× in order to maintain amplitudes near −2.0% throughout the majority of the lower mantle. This latter observation has implications for effective excess temperature (see Methods).

Extended Data Figure 7 Linear resolution analysis for synthetic ‘hanging’ plume input structures in the upper mantle and transition zone.

Like those in Extended Data Figs 4 and 5, these plumes have an overall width of 600 km and a cosine-cap lateral cross-section, as well as −2% maximum amplitude, but are now cut at 410-km (left panels) or 1,000-km (right panels) depth. This experiment is designed to assess the effect of depth-smearing in SEMUCB-WM1. Upper panels, hanging-plume input models. Lower panels, output models when inputs are placed beneath Hawaii. We note that in general the structures retrieved are quite symmetrical and exhibit the appropriate depth extent, with the exception of the plume truncated at 1,000 km, which shows a weak eastward-trending band extending to the CMB. We note that this artefact is very weak, generally less than 0.1% amplitude, as illustrated in the bottom panel, where structure below 0.1% is masked (that is, the band is at least 20× weaker than the −2% input structure). Furthermore, we note that this feature is not at all like the plume we image beneath Hawaii, as it possesses a very different trend and amplitude profile.

Extended Data Figure 8 Linear resolution analysis for synthetic ‘hanging’ plume input structures in the upper mantle and transition zone.

This figure is similar to Extended Data Fig. 7, but now examines recovery beneath Iceland. Upper panels, hanging-plume input models. Lower panels, output models when inputs are placed beneath Iceland. The retrieved structures are again quite symmetrical and exhibit the appropriate depth extent, although amplitude recovery is slightly less impressive than that observed beneath Hawaii (consistent with the results of Extended Data Figs 4 and 5).

Extended Data Table 1 Plumes detected in the lower mantle in model SEMUCB-WM14, and corresponding hotspots

Supplementary information

Supplementary Information

This file contains, Supplementary Text and Data, including a Supplementary Discussion, Supplementary Figures 1-10 and additional references. (PDF 2067 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

French, S., Romanowicz, B. Broad plumes rooted at the base of the Earth's mantle beneath major hotspots. Nature 525, 95–99 (2015). https://doi.org/10.1038/nature14876

Download citation

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing