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Magma-assisted rifting in Ethiopia

Nature volume 433, pages 146–148 (2005)Cite this article

Abstract

The rifting of continents and evolution of ocean basins is a fundamental component of plate tectonics, yet the process of continental break-up remains controversial. Plate driving forces have been estimated to be as much as an order of magnitude smaller than those required to rupture thick continental lithosphere1,2. However, Buck1 has proposed that lithospheric heating by mantle upwelling and related magma production could promote lithospheric rupture at much lower stresses. Such models of mechanical versus magma-assisted extension can be tested, because they predict different temporal and spatial patterns of crustal and upper-mantle structure. Changes in plate deformation produce strain-enhanced crystal alignment and increased melt production within the upper mantle, both of which can cause seismic anisotropy3. The Northern Ethiopian Rift is an ideal place to test break-up models because it formed in cratonic lithosphere with minor far-field plate stresses4,5. Here we present evidence of seismic anisotropy in the upper mantle of this rift zone using observations of shear-wave splitting. Our observations, together with recent geological data, indicate a strong component of melt-induced anisotropy with only minor crustal stretching, supporting the magma-assisted rifting model in this area of initially cold, thick continental lithosphere.

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Figure 1: SKS splitting results in the region of the Northern Ethiopian Rift.
Figure 2: Shear-wave splitting parameters, φ (top panels) and δt (bottom panels), as a function of distance perpendicular to the rift (NW to SE) (left panels) and distance along the rift moving from the SW to the NE (right panels).

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References

  1. Buck, W. R. in Rheology and Deformation of the Lithosphere at Continental Margins (eds Karner, G. D., Taylor, B., Driscoll, N. W. & Kohlstedt, D. L.) 1–30 (Columbia Univ. Press, New York, 2004)

    Book  Google Scholar 

  2. Bott, M. H. P. Sublithospheric loading and plate-boundary forces. Phil. Trans. R. Soc. Lond. 337, 83–93 (1991)

    Article  ADS  Google Scholar 

  3. Kendall, J.-M. in Earth's Deep Interior: Mineral Physics and Tomography from the Atomic to the Global Scale (eds Karato, S., Stixrude, L., Liebermann, R. C., Masters, T. G. & Forte, A. M.) 149–175 (Geophys. Monogr. Ser. 117, American Geophysical Union, Washington DC, 2000)

    Google Scholar 

  4. McClusky, S., Reilinger, R., Mahmoud, S., Ben Sari, D. & Tealab, A. GPS constraints on Africa (Nubia) and Arabia plate motions. Geophys. J. Int. 155, 126–138 (2003)

    Article  ADS  Google Scholar 

  5. Chu, D. & Gordon, R. Evidence for motion between Nubia and Somalia along the Southwest Indian Ridge. Nature 398, 64–67 (1998)

    Article  ADS  Google Scholar 

  6. Maguire, P. et al. Geophysical project in Ethiopia studies continental breakup. Eos 84, 337–340 (2003)

    Article  ADS  Google Scholar 

  7. Ebinger, C. J. & Casey, M. Continental breakup in magmatic provinces: An Ethiopian example. Geology 29, 527–530 (2001)

    Article  ADS  Google Scholar 

  8. Mackenzie, G. D., Thybo, H. & Maguire, P. K. H. Crustal velocity structure across the Main Ethiopian Rift: results from 2-dimensional wide-angle seismic modelling. Geophys. J. Int. (in the press)

  9. Bastow, I., Stuart, G. W., Kendall, J-M. & Ebinger, C. J. Upper-mantle seismic structure in a region of incipient continental breakup: Northern Ethiopian Rift. Geophys. J. Int. (submitted)

  10. Silver, P. G. Seismic anisotropy beneath the continents. Annu. Rev. Earth Planet. Sci. 24, 385–432 (1996)

    Article  ADS  CAS  Google Scholar 

  11. Savage, M. Seismic anisotropy and mantle deformation: What have we learned from shear wave splitting. Rev. Geophys. 37, 65–106 (1999)

    Article  ADS  Google Scholar 

  12. Gao, S. et al. SKS splitting beneath continental rift zones. J. Geophys. Res. 102, 22781–22797 (1997)

    Article  ADS  Google Scholar 

  13. Ayele, A., Stuart, G. W. & Kendall, J.-M. Insights into rifting from shear-wave splitting and receiver functions: an example from Ethiopia. Geophys. J. Int. 157, 354–362 (2004)

    Article  ADS  Google Scholar 

  14. Walker, K., Nyblade, A. A., Klemperer, S. L., Bokelmann, G. H. R. & Owens, T. J. On the relationship between extension and anisotropy: Constraints from shear wave splitting across the East Africa Plateau. J. Geophys. Res. 109, doi:10.1029/2003JB002866 (2003)

  15. Gashawbeza, E. M., Klemperer, S. L., Nyblade, A. A., Walker, K. T. & Keranen, K. M. Shear-wave splitting in Ethiopia: Percambrian mantle anisotropy locally modified by Neogene rifting. Geophys. Res. Lett. 31, doi:10.1029/2004GL020471 (2004)

  16. Hadiouche, O., Jobert, N. & Montagner, J.-P. Anisotropy of the African Continent inferred from surface waves. Phys. Earth Planet. Inter. 58, 61–81 (1989)

    Article  ADS  Google Scholar 

  17. Rumpker, G. & Ryberg, T. New ‘Fresnel zone’ estimates for shear-wave splitting observations from finite difference modelling. Geophys. Res. Lett. 27, 2005–2008 (2000)

    Article  ADS  Google Scholar 

  18. Barruol, G. & Ben-Ismail, W. Upper mantle anisotropy beneath the African IRIS and GEOSCOPE stations. Geophys. J. Int. 146, 549–561 (2001)

    Article  ADS  Google Scholar 

  19. Wolfenden, E., Ebinger, C., Yirgu, G., Deino, A. & Ayalew, D. Evolution of the northern Main Ethiopian rift: Birth of a triple junction. Earth Planet. Sci. Lett. 224, 213–228 (2004)

    Article  ADS  CAS  Google Scholar 

  20. Abdelselam, M. & Stern, R. Sutures and shear zones in the Arabia-Nubian shield. J. Afr. Earth Sci. 23, 289–310 (1996)

    Article  ADS  Google Scholar 

  21. Moore, H. & Davidson, A. Rift structure in southern Ethiopia. Tectonophysics 46, 159–173 (1978)

    Article  ADS  Google Scholar 

  22. Blackman, D. K. et al. Teleseismic imaging of subaxial flow at mid-ocean ridges: travel-time effects of anisotropic mineral texture in the mantle. Geophys. J. Int. 127, 415–426 (1996)

    Article  ADS  Google Scholar 

  23. Vauchez, A., Tommasi, A., Barruol, G. & Maumus, J. Upper mantle deformation and seismic anisotropy in continental rifts. Phys. Chem. Earth 25, 111–117 (2000)

    Article  Google Scholar 

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

    Article  ADS  CAS  Google Scholar 

  25. Kendall, J.-M. Teleseismic arrivals at a mid-ocean ridge: effects of mantle melt and anisotropy. Geophys. Res. Lett. 21, 301–304 (1994)

    Article  ADS  Google Scholar 

  26. Rooney, T. O., Furman, T., Yirgu, G. & Ayalew, D. Structure of the Ethiopian lithosphere: evidence from mantle xenoliths. Geochim. Cosmochim. Acta (submitted)

  27. Holtzman, B. K. et al. Melt segregation and strain partitioning: Implications for seismic anisotropy and mantle flow. Science 301, 1227–1230 (2003)

    Article  ADS  CAS  Google Scholar 

  28. Sleep, N. H. Lateral flow and ponding of starting plume material. J. Geophys. Res. 102, 10001–10012 (1997)

    Article  ADS  Google Scholar 

  29. Wernicke, B. Low angle normal faults in Basin and Range province: Nappe tectonics in an extending orogen. Nature 291, 645–648 (1981)

    Article  ADS  Google Scholar 

  30. Bilham, R. et al. Secular and tidal strain across the Ethiopian rift. Geophys. Res. Lett. 27, 2789–2984 (1999)

    Article  ADS  Google Scholar 

Download references

Acknowledgements

We thank the EAGLE working group6 and especially L. Asfaw and A. Ayele for help with the EAGLE experiment. We thank SEIS-UK for equipment and technical support. We also thank M. Savage, R. Huismans, T. Furman, R. Buck and E. Calais for comments on the manuscipt and A. Parr for help with the data processing. Funding was provided by NERC-UK grants.

Author information

Authors and Affiliations

  1. School of Earth Sciences, University of Leeds, UK, Leeds, LS2 9JT

    J.-M. Kendall, G. W. Stuart & I. D. Bastow

  2. Department of Geology, Royal Holloway, University of London, UK, Egham, Surrey, TW20 0EX

    C. J. Ebinger & D. Keir

Authors
  1. J.-M. Kendall
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  2. G. W. Stuart
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  3. C. J. Ebinger
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  4. I. D. Bastow
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  5. D. Keir
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Corresponding author

Correspondence to J.-M. Kendall.

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The authors declare that they have no competing financial interests.

Supplementary information

Supplementary Figure 1a

Examples of SKS splitting at one of the BB stations, GEWE, and one of the rift valley stations, E48. (PDF 173 kb)

Supplementary Figure 1b

Examples of SKS splitting at one of the BB stations, GEWE, and one of the rift valley stations, E48. (PDF 209 kb)

Supplementary Table 1

List of events used in shear-wave splitting analysis. Last column indicates phase used in splitting analysis. (PDF 21 kb)

Supplementary Table 2

Summary of splitting parameters obtained for each station. (PDF 26 kb)

Supplementary Figure and Table Legends

Legends to accompany the above. (DOC 22 kb)

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Kendall, JM., Stuart, G., Ebinger, C. et al. Magma-assisted rifting in Ethiopia. Nature 433, 146–148 (2005). https://doi.org/10.1038/nature03161

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