Polar wandering in mantle convection models

Abstract

We calculate polar motion in models of 3-D spherical mantle convection at Rayleigh numbers up to 10exp8 which include internal heating, radial viscosity variations, and an endothermic phase change. Isoviscous models yield rapid polar motion of order 3 degree/Myr, but a factor of 30 increase in viscosity with depth reduces the rate of polar motion to about 0.5 degree/Myr due to stabilization of the large-scale pattern of convection. Avalanching due to an endothermic phase change causes pulsating inertial interchange polar excursions of order $80-110^o$ and of duration 20-70 Myr. A layered viscosity model with an endothermic phase change yields only one inertial interchange event in 600 million years. These models show that the slow observed rate of post-Paleozoic true polar wander is not incompatible with higher rates inferred for earlier times.

BibTeX
@article{id73,
  author = {Richards, M.A. and Bunge, H.-P. and Ricard, Y. and Baumgardner, J.R.},
  journal = {Geophys. Res. Lett.},
  language = {en},
  pages = {1777 - 1780},
  title = {Polar wandering in mantle convection models},
  volume = {26},
  year = {1999},
}
EndNote
%O Journal Article
%A Richards, M.A.
%A Bunge, H.-P.
%A Ricard, Y.
%A Baumgardner, J.R.
%J Geophys. Res. Lett.
%G en
%P 1777 - 1780
%T Polar wandering in mantle convection models
%V 26
%D 1999