Letter | Published:

Dynamic topography, plate driving forces and the African superswell

Subjects

Abstract

Discovering the connection between processes observed to occur at the surface of the Earth and its internal dynamics remains an essential goal in the Earth sciences. Deep mantle structure, as inferred from seismic tomography or subduction history, has been shown to account well for the observed surface gravity fieldand motions of tectonic plates1,2,3. But the origin of certain large-scale features, such as the anomalous elevation of the southern and eastern African plateaux, has remained controversial. Whereas the average elevation of most cratons is between 400 and 500 m, the southern African plateau stands more than 1 km above sea level, with the surrounding oceans possessing a residual bathymetry in excess of 500 m (ref. 4). Global seismic tomography studies have persistently indicated the existence of a large-scale low-velocity anomaly beneath the African plate5,6,7,8,9,10 and here we show that mantle flow induced by the density variations inferred from these velocity anomalies can dynamically support the excess elevation of the African ‘superswell’. We also find that this upwelling mantle flow—which is most intense near the core–mantle boundary—constitutes a significant driving force for tectonic plates in the region.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1

    Hager, B. H.et al. Lower mantle heterogeneity, dynamic topography and the geoid. Nature 313, 541–454 (1985).

  2. 2

    Ricard, Y., Richards, M., Lithgow-Bertelloni, C. & LeStunff, Y. Ageodynamical model of mantle density heterogeneity. J. Geophys. Res. 98, 21895–21909 (1993).

  3. 3

    Lithgow-Bertelloni, C. & Richards, M. A. Cenozoic plate driving forces. Geophys. Res. Lett. 22, 1317–1320 (1995).

  4. 4

    Nyblade, A. A. & Robinson, S. W. The African superswell. Geophys. Res. Lett. 21, 765–768 (1994).

  5. 5

    Dziewonski, A. M. Mapping the lower mantle: determination of lateral heterogeneity in P velocity up to degree and order 6. J. Geophys. Res. 89, 5929–5952 (1984).

  6. 6

    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).

  7. 7

    Li, X. D. & Romanowicz, B. Global shear-velocity model developed using nonlinear asymptotic coupling theory. J. Geophys. Res. 101, 22245–22272 (1996).

  8. 8

    Masters, G., Johnson, S., Laske, G. & Bolton, H. Ashear-velocity model of the mantle. Phil. Trans. R. Soc. Lond. A 354, 1385–1411 (1996).

  9. 9

    Grand, S. P., van der Hilst, R. D. & Widiyantoro, S. Global seismic tomography: a snapshot of convection in the Earth. GSA Today 7, 1–7 (1997).

  10. 10

    van der Hilst, R., Widiyantoro, S. & Engdahl, R. Evidence for deep mantle circulation from global tomography. Nature 386, 578–584 (1997).

  11. 11

    Gurnis, M. Phanerozoic marine inundation of continents driven by dynamic tomography above subducting slabs. Nature 364, 589–593 (1993).

  12. 12

    Nyblade, A. A.et al. Terrestrial heat flow in east and southern Africa. J. Geophys. Res. 95, 17371–17384 (1990).

  13. 13

    Brown, C. & Girdler, R. W. Interpretation of African gravity and its implication for the breakup of the continents. J. Geophys. Res. 85, 6443–6455 (1980).

  14. 14

    Cazenave, A., Souriau, A. & Dominh, K. Global coupling of Earth surface topography with hotspots, geoid and mantle heterogeneities. Nature 340, 54–57 (1989).

  15. 15

    Colin, P. & Fleitout, L. Topography of the ocean floor: thermal evolution of the lithosphere and interaction of mantle heterogeneities with the lithosphere. Geophys. Res. Lett. 11, 1961–1964 (1990).

  16. 16

    LeStunff, Y. & Ricard, Y. Topography and geoid due to lithospheric mass anomalies. Geophys. J. Int. 122, 982–990 (1995).

  17. 17

    Thoraval, C., Machetel, P. & Cazenave, A. Locally layered convection inferred from dynamic models of the earth's mantle. Nature 375, 777–780 (1995).

  18. 18

    LeStunff, Y. & Ricard, Y. Partial advection of equidensity surfaces: a solution for the dynamic topography problems?. J. Geophys. Res. 102, 24655–24667 (1997).

  19. 19

    Christensen, U. R. Dynamic phase boundary topography by latent heat effects. Earth Planet. Sci. Lett. 154, 295–306 (1998).

  20. 20

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

  21. 21

    Lithgow-Bertelloni, C. & Gurnis, M. Cenozoic subsidence and uplift of continents from time-varying dynamic topography. Geology 25, 735–738 (1997).

  22. 22

    Farnetani, C. G. & Richards, M. A. Numerical investigations of the mantle plume initiation model for flood basalt events. J. Geophys. Res. 99, 13813–13833 (1994).

  23. 23

    Richards, M. A. & Hager, B. H. Geoid anomalies in a dynamic earth. J. Geophys. Res. 89, 5987–6002 (1984).

  24. 24

    Ricard, Y., Fleitout, L. & Froidevaux, C. Geoid heights and lithospheric stresses for a dynamic earth. Ann. Geophys. 2, 267–286 (1984).

  25. 25

    Mitrovica, J. X. & Forte, A. M. Radial profile of mantle viscosity: results from the joint inversion of convection and postglacial rebound observables. J. Geophys. Res. 102, 2751–2769 (1997).

  26. 26

    Karato, S.-I. Importance of anelasticity in the interpretation of seismic tomography. Geophys. Res. Lett. 20, 1623–1626 (1993).

  27. 27

    Forte, A. M., Peltier, W. R., Dziewonski, A. M. & Woodward, R. L. Dynamic surface topography—a new interpretation based upon mantle flow models derived from seismic tomography. Geophys. Res. Lett. 19, 1555–1558 (1993).

  28. 28

    White, N. & Lovell, B. Measuring the pulse of a plume with the sedimentary record. Nature 387, 888–891 (1997).

Download references

Acknowledgements

We thank S. Grand for providing his model, and A. Nyblade for providing the data for Fig. 1a. We also thank H. Pollack and A. Nyblade for comments. The manuscript was significantly improved by comments from U. Christensen and Y. Ricard. C.L.-B. was supported by a National Science Foundation postdoctoral fellowship; P.G.S. and C.L.-B. were supported by the Carnegie Institution of Washington.

Author information

Correspondence to Carolina Lithgow-Bertelloni.

Supplementary information

  1. Supplementary Information

  2. Supplementary Information

    Supplementary Information (PDF 39 kb)

Rights and permissions

To obtain permission to re-use content from this article visit RightsLink.

About this article

Publication history

  • Received

  • Accepted

  • Issue Date

DOI

https://doi.org/10.1038/26212

Further reading

Figure 1: Comparison of the residual topography over Africa and the predicted dynamic topography given by the subduction history model and Grand's tomographic model9.
Figure 2: Torque magnitudes of individual driving forces for plates in the Atlantic basin.

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.