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AGU: Geophysical Research Letters

 

Keywords

  • planetary evolution
  • plate tectonics
  • geodynamics

Index Terms

  • Planetary Sciences: Solid Surface Planets: Interiors
  • Planetary Sciences: Solid Surface Planets: Tectonics
  • Tectonophysics: Dynamics of lithosphere and mantle: general
  • Tectonophysics: Dynamics: gravity and tectonics
  • Tectonophysics: Evolution of the Earth

Abstract

Geological consequences of super-sized Earths

C. O'Neill

GEMOC ARC National Key Centre, Department of Earth and Planetary Science, Macquarie University, Sydney, New South Wales, Australia

A. Lenardic

Department of Earth Science, Rice University, Houston, Texas, USA

The discovery of terrestrial-scale extrasolar planets, and their calculated abundance in the galaxy, has prompted speculation on their surface conditions and thermal structure. Both are dependent on the tectonic regime of a planet, which is itself a function of the balance between driving forces, and the resistive strength of the lithosphere. Here we use mantle convection simulations to show that simply increasing planetary radius acts to decrease the ratio of driving to resisting stresses, and thus super-sized Earths are likely to be in an episodic or stagnant lid regime. This effect is robust when associated increases in gravity are included, as the more dominant effect is increased fault strength rather than greater buoyancy forces. The thermo-tectonic evolution of large terrestrial planets is more complex than often assumed, and this has implications for the surface and conditions habitability of such worlds.

Received 6 May 2007; accepted 22 August 2007; published 11 October 2007.

Citation: O'Neill, C., and A. Lenardic (2007), Geological consequences of super-sized Earths, Geophys. Res. Lett., 34, L19204, doi:10.1029/2007GL030598.

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