Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Skew of mantle upwelling beneath the East Pacific Rise governs segmentation

Abstract

Mantle upwelling is essential to the generation of new oceanic crust at mid-ocean ridges, and it is generally assumed that such upwelling is symmetric beneath active ridges. Here, however, we use seismic imaging to show that the isotropic and anisotropic structure of the mantle is rotated beneath the East Pacific Rise. The isotropic structure defines the pattern of magma delivery from the mantle to the crust. We find that the segmentation of the rise crest between transform faults correlates well with the distribution of mantle melt. The azimuth of seismic anisotropy constrains the direction of mantle flow, which is rotated nearly 10° anticlockwise from the plate-spreading direction. The mismatch between the locus of mantle melt delivery and the morphologic ridge axis results in systematic differences between areas of on-axis and off-axis melt supply. We conclude that the skew of asthenospheric upwelling and transport governs segmentation of the East Pacific Rise and variations in the intensity of ridge crest processes.

Your institute does not have access to this article

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Location and geometry of the seismic experiment and tomographic image of the mantle low-velocity zone (MLVZ) and orientation of mantle anisotropy.
Figure 2: Map of the distribution of seismic ray paths and mean P n delay times versus azimuth and latitude.
Figure 3: Normalized data misfit following tomographic inversion versus azimuth of seismic anisotropy imposed on starting model.
Figure 4: Proposed model of segmentation beneath the East Pacific Rise.

References

  1. Whitehead, J. A., Dick, H. J. B. & Schouten, H. A mechanism for magmatic accretion under spreading centres. Nature 312, 146–148 (1984)

    ADS  CAS  Article  Google Scholar 

  2. Schouten, H., Klitgord, K. D. & Whitehead, J. A. Segmentation of mid-ocean ridges. Nature 317, 225–229 (1985)

    ADS  Article  Google Scholar 

  3. Macdonald, K. C. et al. A new view of the mid-ocean ridge from the behaviour of ridge-axis discontinuities. Nature 335, 217–225 (1988)

    ADS  Article  Google Scholar 

  4. Macdonald, K. C., Scheirer, D. S. & Carbotte, S. M. Mid-ocean ridges: Discontinuities, segments and giant cracks. Science 253, 986–994 (1991)

    ADS  CAS  Article  Google Scholar 

  5. Langmuir, C. H., Bender, J. F. & Batiza, R. Petrological and tectonic segmentation of the East Pacific Rise, 5°30'-14°30'N. Nature 322, 422–429 (1986)

    ADS  CAS  Article  Google Scholar 

  6. Toomey, D. R., Purdy, G. M., Solomon, S. C. & Wilcock, W. S. D. The three-dimensional seismic velocity structure of the East Pacific Rise near latitude 9°30'N. Nature 347, 639–645 (1990)

    ADS  Article  Google Scholar 

  7. Lonsdale, P. Segmentation of the Pacific-Nazca Spreading Center, 1°N-20°S. J. Geophys. Res. 94, 12197–12226 (1989)

    ADS  Article  Google Scholar 

  8. Parmentier, E. M. & Morgan, J. P. Spreading rate dependence of three-dimensional structure in oceanic spreading centers. Nature 348, 325–328 (1990)

    ADS  Article  Google Scholar 

  9. Bell, R. E. & Buck, W. R. Crustal control of ridge segmentation inferred from observations of the Reykjanes ridge. Nature 357, 583–586 (1992)

    ADS  Article  Google Scholar 

  10. Sempéré, J.-C. & Macdonald, K. C. Deep-tow studies of the overlapping spreading centers at 9°03'N on the East Pacific Rise. Tectonics 5, 881–900 (1986)

    ADS  Article  Google Scholar 

  11. Carbotte, S. M. & Macdonald, K. C. East Pacific Rise 8°-10°30'N: Evolution of ridge segments and discontinuities from SeaMARC II and three-dimensional magnetic studies. J. Geophys. Res. 97, 6959–6982 (1992)

    ADS  Article  Google Scholar 

  12. Smith, M. C. et al. Magmatic processes and segmentation at a fast spreading mid-ocean ridge; detailed investigation of an axial discontinuity on the East Pacific Rise crest at 9°37'N. Geochem. Geophys. Geosyst. 2 doi: 10.1029/2000GC000134 (2001)

  13. Kent, G. M., Harding, A. J. & Orcutt, J. A. Distribution of magma beneath the East Pacific Rise between the Clipperton Transform and the 9°17'N Deval from forward modeling of common depth point data. J. Geophys. Res. 98, 13945–13969 (1993)

    ADS  Article  Google Scholar 

  14. Dunn, R. A., Toomey, D. R. & Solomon, S. C. Three-dimensional seismic structure and physical properties of the crust and shallow mantle beneath the East Pacific Rise at 9°30'N. J. Geophys. Res. 105, 23537–23555 (2000)

    ADS  Article  Google Scholar 

  15. Scheirer, D. S. & Macdonald, K. C. Variation in cross-sectional area of the axial ridge along the East Pacific Rise: Evidence for the magmatic budget of a fast spreading center. J. Geophys. Res. 98, 7871–7885 (1993)

    ADS  Article  Google Scholar 

  16. Detrick, R. S. et al. Multi-channel seismic imaging of a crustal magma chamber along the East Pacific Rise. Nature 326, 35–41 (1987)

    ADS  Article  Google Scholar 

  17. Vera, E. E. et al. The structure of 0- to 0.2-m.y.-old oceanic crust at 9°N on the East Pacific Rise from expanded spread profiles. J. Geophys. Res. 95, 15529–15556 (1990)

    ADS  Article  Google Scholar 

  18. Barth, G. A. & Mutter, J. C. Variability in oceanic crustal thickness and structure: Multichannel seismic reflection results from the northern East Pacific Rise. J. Geophys. Res. 101, 17951–17975 (1996)

    ADS  Article  Google Scholar 

  19. Canales, J. P., Detrick, R. S., Toomey, D. R. & Wilcock, W. S. D. Segment-scale variations in the crustal structure of 150–300 kyr old fast spreading oceanic crust (East Pacific Rise, 8°15'N-10°5'N) from wide-angle seismic refraction profiles. Geophys. J. Int. 152, 766–794 (2003)

    ADS  Article  Google Scholar 

  20. Batiza, R. & Niu, Y. Petrology and magma chamber processes at the East Pacific Rise 9°30'N. J. Geophys. Res. 97, 6779–6797 (1992)

    ADS  CAS  Article  Google Scholar 

  21. Perfit, M. R. et al. Small-scale spatial and temporal variations in mid-ocean ridge crest magmatic processes. Geology 22, 375–379 (1994)

    ADS  CAS  Article  Google Scholar 

  22. Haymon, R. M. et al. Hydrothermal vent distribution along the East Pacific Rise crest (9°09'-54'N) and its relationship to magmatic and tectonic processes on fast-spreading mid-ocean ridges. Earth Planet. Sci. Lett. 102, 513–534 (1991)

    ADS  Article  Google Scholar 

  23. Von Damm, K. L. Chemistry of hydrothermal vent fluids from 9°-10°, East Pacific Rise: “Time zero,” the intermediate posteruptive period. J. Geophys. Res. 105, 11203–11222 (2000)

    ADS  CAS  Article  Google Scholar 

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

    ADS  Article  Google Scholar 

  25. Key, K. & Constable, S. Mantle upwelling beneath the East Pacific Rise at 9°30'N. Eos (Fall Meet. Suppl.) 87 (52), abstr. B31B–1114. (2006)

  26. Crawford, W. C. & Webb, S. C. Variations in the distribution of magma in the lower crust and at the Moho beneath the East Pacific Rise at 9°-10°N. Earth Planet. Sci. Lett. 203, 117–130 (2002)

    ADS  CAS  Article  Google Scholar 

  27. Singh, S. C. et al. Seismic reflection images of the Moho underlying melt sills at the East Pacific Rise. Nature 442, 287–290 (2006)

    ADS  CAS  Article  Google Scholar 

  28. Kent, G. M. et al. Evidence from three-dimensional seismic reflectivity images for enhanced melt supply beneath mid-ocean-ridge discontinuities. Nature 406, 614–618 (2000)

    ADS  CAS  Article  Google Scholar 

  29. Dunn, R. A., Toomey, D. R., Detrick, R. S. & Wilcock, W. S. D. Continuous mantle melt supply beneath an overlapping spreading center on the East Pacific Rise. Science 291, 1955–1958 (2001)

    ADS  CAS  Article  Google Scholar 

  30. Faul, U. H., Toomey, D. R. & Waff, H. S. Intergranular basaltic melt is distributed in thin, elongated inclusions. Geophys. Res. Lett. 21, 29–32 (1994)

    ADS  Article  Google Scholar 

  31. Hammond, W. C. & Humphreys, E. D. Upper mantle seismic wave velocity: Effects of realistic partial melt geometries. J. Geophys. Res. 105, 10975–10986 (2000)

    ADS  Article  Google Scholar 

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

    Book  Google Scholar 

  33. Ben Ismaïl, W. & Mainprice, D. An olivine fabric database: an overview of upper mantle fabrics and seismic anisotropy. Tectonophysics 296, 145–157 (1998)

    ADS  Article  Google Scholar 

  34. Blackman, D. K., Wenk, H.-R. & Kendall, J. M. Seismic anisotropy of the upper mantle: 1. Factors that affect mineral texture and effective elastic properties. Geochem. Geophys. Geosyst. 3 doi: 10.1029/2001GC000248 (2002)

  35. Pockalny, R. A., Fox, P. J., Fornari, D. J., Macdonald, K. C. & Perfit, M. R. Tectonic reconstruction of the Clipperton and Siqueiros Fracture Zones: Evidence and consequences of plate motion change for the last 3 Myr. J. Geophys. Res. 102, 3167–3181 (1997)

    ADS  Article  Google Scholar 

  36. Richards, M. A. & Lithgow-Bertelloni, C. Plate motion changes, the Hawaiian-Emperor bend, and the apparent success and failure of geodynamic models. Earth Planet. Sci. Lett. 137, 19–27 (1996)

    ADS  Article  Google Scholar 

  37. White, S. M., Haymon, R. M., Fornari, D. J., Perfit, M. R. & Macdonald, K. C. Correlation between volcanic and tectonic segmentation of fast-spreading ridges: Evidence from volcanic structures and lava flow morphology on the East Pacific Rise at 9°-10°N. J. Geophys. Res. 107 doi: 10.1029/2001JB000571 (2002)

  38. Toomey, D. R., Solomon, S. C. & Purdy, G. M. Tomographic imaging of the shallow crustal structure of the East Pacific Rise at 9°30'N. J. Geophys. Res. 99, 24135–24157 (1994)

    ADS  Article  Google Scholar 

  39. Tian, T., Wilcock, W. S. D., Toomey, D. R. & Detrick, R. S. Seismic heterogeneity in the upper crust near the 1991 eruption site on the East Pacific Rise. Geophys. Res. Lett. 27, 2369–2372 (2000)

    ADS  Article  Google Scholar 

  40. Dunn, R. A. & Toomey, D. R. Seismological evidence for three-dimensional melt migration beneath the East Pacific Rise. Nature 388, 259–262 (1997)

    ADS  CAS  Article  Google Scholar 

  41. Nicolas, A. Structures of Ophiolites and Dynamics of Oceanic Lithosphere 70–77 (ed. Nicolas, A.) (Kluwer Academic, Dordrecht, 1989)

    Book  Google Scholar 

  42. Jousselin, D., Nicolas, A. & Boudier, F. Detailed mapping of a mantle diapir below a paleo-spreading center in the Oman ophiolite. J. Geophys. Res. 103, 18153–18170 (1998)

    ADS  Article  Google Scholar 

  43. Fornari, D. J., Haymon, R. M., Perfit, M. R., Gregg, T. K. P. & Edwards, M. H. Axial summit trough of the East Pacific Rise 9°-10°N: Geological constraints and evolution of the axial zone of fast spreading mid-ocean ridges. J. Geophys. Res. 103, 9827–9855 (1998)

    ADS  Article  Google Scholar 

  44. Wright, D. J., Haymon, R. M. & Fornari, D. J. Crustal fissuring and its relationship to magmatic and hydrothermal processes on the East Pacific Rise crest (9°12' to 54'N). J. Geophys. Res. 100, 6097–6120 (1995)

    ADS  Article  Google Scholar 

  45. Soule, S. A. et al. Channelized lava flows at the East Pacific Rise crest 9°-10°N: The importance of off-axis lava transport in developing the architecture of young oceanic crust. Geochem. Geophys. Geosyst. 6 doi: 10.1029/2005GC000912 (2005)

Download references

Acknowledgements

We thank the officers and crew of the RV Maurice Ewing and members of the scientific party for their assistance. D.R.T. thanks E. Hooft and E. Humphreys for numerous discussions and J. Karson, T. Durant and D. Villagomez for comments. Supported by the RIDGE and RIDGE 2000 Programs, Ocean Sciences Division, NSF.

Author Contributions All authors participated in the experimental design, the collection of the data and in several stages of data reduction and analysis. D.R.T. conducted the tomographic analysis and wrote the manuscript with comments from co-authors.

Author information

Authors and Affiliations

Authors

Corresponding author

Correspondence to Douglas R. Toomey.

Ethics declarations

Competing interests

Reprints and permissions information is available at www.nature.com/reprints. The authors declare no competing financial interests.

Supplementary information

Supplementary Information

This file contains Supplementary Methods, Supplementary Figures S1- S5 with Legends and additional references. (PDF 2694 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Toomey, D., Jousselin, D., Dunn, R. et al. Skew of mantle upwelling beneath the East Pacific Rise governs segmentation. Nature 446, 409–414 (2007). https://doi.org/10.1038/nature05679

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nature05679

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

Quick links

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