The rotational stability of a convecting earth: Assessing inferences of rapid TPW in the late cretaceous

N. H. Chan, J. X. Mitrovica, I. Matsuyama, J. R. Creveling, S. Stanley

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

We outline a linearized rotational stability theory for predicting the time dependence of true polar wander (TPW) on a Maxwell viscoelastic body in response to mantle convective loading. The new theory is based on recent advances in ice age rotation theory. A comparison between predictions based on the new theory and analytic expressions for equilibrium (infinite-time) TPW on planetary models with elastic lithospheres demonstrates that the linearized theory can, in the case of loading at mid-latitudes, predict TPW of over 20° to better than 5 per cent accuracy. We present predictions of TPW for loading with periodic and net ramp-up time histories. Moreover, we compare the time dependence of TPW under assumptions consistent with the canonical equilibrium stability theory adopted in most previous analyses of convection-induced TPW, and a stability theory that includes two effects that have not been considered in previous geophysical analyses: (1) the so-called 'remnant rotational bulge' associated with the imperfect reorientation of the rotational bulge due to the presence of an elastic lithosphere; and (2) a stable (over the timescale of the forcing) excess ellipticity. As a first application of the new theory, we consider recent inferences of rapid (order 1 Myr) TPW motion of amplitude 10°-20° during the Late Cretaceous. We conclude that excursions of this amplitude and timescale are physically implausible.

Original languageEnglish (US)
Pages (from-to)1319-1333
Number of pages15
JournalGeophysical Journal International
Volume187
Issue number3
DOIs
StatePublished - Dec 1 2011
Externally publishedYes

Keywords

  • Earth rotation variations
  • Palaeomagnetic secular variation
  • Rheology: crust and lithosphere

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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