Mantle convection and plate tectonics on Earth-like exoplanets

Details Mantle convection and plate tectonics on Earth-like exoplanets Mantle convection and plate tectonics on Earth-like exoplanets

Dec 2009

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufm.p42b..02s&link_type=abstract

American Geophysical Union, Fall Meeting 2009, abstract #P42B-02

Physics

[5475] Planetary Sciences: Solid Surface Planets / Tectonics, [8155] Tectonophysics / Plate Motions: General, [8162] Tectonophysics / Rheology: Mantle

Scientific paper

The likelihood of plate tectonics on exoplanets larger than Earth can be assessed using either scaling laws or numerical models describing mantle thermal convection. We investigate the parameters which control the ratio of convective driving forces to lithosphere resisting forces. Two papers, Valencia et al. (AstroPhys. J., 670, L45-L48, 2007) and O’Neill and Lenardic (Geophys. Res. Lett., 34, L19204, 2007), came to opposite conclusions based on scaling laws and numerical calculations, respectively. The different assumptions and parameters used in each study are compared. The definition of thermal boundary layer and lithosphere and the use of their characteristics in the scaling laws are clarified. We show that Valencia et al. (2007) overestimate the ratio of driving forces to resistive forces because they infer too large values for both the thickness of the thermal boundary layer and the length of the plate and too small a value for the yield strength. We show that this ratio is so weakly dependent on the size of an Earth-like planet that other parameters such as presence of water, heating per unit mass, upper mantle thickness, etc., may actually determine the occurrence or not of plate tectonics. The numerical calculations of O’Neill and Lenardic (2007) show the importance of 2D simulations for determining the values of the velocity below the lithosphere, the convective stresses, and the plate dimensions. It demonstrates the need for 3D spherical numerical simulations. Their conclusion that super-Earths would not have plate tectonics depends on a number of assumptions including the constancy of heat-flux as a function of planetary size. We present a 3D spherical scaling including the increase of heat flux with the size of a planet showing that larger Earth-like planets would be marginally in the mobile lid convection regime reinforcing our caution that other factors may tip the balance. The present study points out the importance of the distance between plumes for calculating the driving force. It is suggested that the formation of hot plumes at the core-mantle boundary and their interaction with the upper thermal boundary layer may play an important role in triggering plate tectonics. Part of this work has been carried out at the Jet Propulsion Laboratory-California Institute of Technology, under contract with NASA.

Affiliated with

Also associated with

No associations

Rating

Mantle convection and plate tectonics on Earth-like exoplanets does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Mantle convection and plate tectonics on Earth-like exoplanets, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mantle convection and plate tectonics on Earth-like exoplanets will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1772124