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Published February 1997 | public
Journal Article

Layered mantle convection: A model for geoid and topography


The long-wavelength geoid and topography are dynamic effects of a convecting mantle. The long-wavelength geoid of the Earth is controlled by density variations in the mantle and has been explained by circulation models involving whole mantle flow. However, the relationship of long-wavelength topography to mantle circulation has been a puzzling problem in geodynamics. We show that the dynamic topography is mainly due to density variations in the upper mantle, even after the effects of lithospheric cooling and crustal thickness variation are taken into account. Layered mantle convection, with a shallow origin for surface dynamic topography, is consistent with the spectrum, small amplitude and pattern of the topography. Layered mantle convection, with a barrier about 250 km deeper than the 670 km phase boundary, provides a self-consistent geodynamic model for the amplitude and pattern of both the long-wavelength geoid and surface topography.

Additional Information

© 1997 Elsevier Science B.V. Received 28 May 1996; accepted 4 October 1996. We thank Anny Cazenave for the residual topography data, Scott King for the viscosity structure and Michael Gurnis, David Stevenson and Craig Scrivner for reviews. This work was funded by NSF grant EAR 92-18390. Contribution No. 5598, Division of Geological and Planetary Sciences, California Institute of Technology. [RV]

Additional details

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