Changes

A flaw of viscoelastic-plastic models of exoplanet geodynamics is in order for plate tectonics to be initiated, unrealistically low yield stress values are required. Additionally, plates in viscoelastic-plastic models have no deformation memory, i.e. as soon as the stress on a lithospheric plate drops below its yield stress it returns to its pre-deformation strength. This stands in contrast to Earth-based observations, which show that plates preferentially break along preexisting areas of deformation.<ref name=Foley_etal_2012>Foley, B.J.; Bercovici, D.; Landuyt, W. (15 May 2012). "The conditions for plate tectonics on super-Earths: Inferences from convection models with damage". Earth and Planetary Science Letters. 331-332: 281–290. doi:10.1016/j.epsl.2012.03.028. Retrieved 10 October 2014.</ref>

A flaw of viscoelastic-plastic models of exoplanet geodynamics is in order for plate tectonics to be initiated, unrealistically low yield stress values are required. Additionally, plates in viscoelastic-plastic models have no deformation memory, i.e. as soon as the stress on a lithospheric plate drops below its yield stress it returns to its pre-deformation strength. This stands in contrast to Earth-based observations, which show that plates preferentially break along preexisting areas of deformation.<ref name=Foley_etal_2012>Foley, B.J.; Bercovici, D.; Landuyt, W. (15 May 2012). "The conditions for plate tectonics on super-Earths: Inferences from convection models with damage". Earth and Planetary Science Letters. 331-332: 281–290. doi:10.1016/j.epsl.2012.03.028. Retrieved 10 October 2014.</ref>

Damage theory attempts to address this model flaw by simulating voids created in areas of strain, representing the mechanical pulverization of coarse grains of rock into finer grains. In such models, damage is balanced by “healing”, or the temperature and pressure-driven dynamic recrystallization of smaller grains into larger ones. If the reduction of grain size (damage) is intensely localized in a stagnant lid, an incipient crack in the mantle can turn into a full-blown rift, initiating plate tectonics.<ref name=Landuyt_etal_2008>{{cite journal|last1=Landuyt|first1=W.|last2=Bercovici|first2=D.|last3=Ricard|first3=Y.|title=Plate generation and two-phase damage theory in a model of mantle convection|journal=Geophysical Journal International|date=6 May 2008|volume=174|issue=3|pages=1065–1080|doi=10.1111/j.1365-246X.2008.03844.x|url=http://gji.oxfordjournals.org/content/174/3/1065.short|accessdate=10 October 2014}}</ref> Conversely, a high surface temperature will have more efficient lithospheric healing, which is another potential explanation for why Venus has a stagnant lid and Earth does not.<ref name=Foley_etal_2012 />

Damage theory attempts to address this model flaw by simulating voids created in areas of strain, representing the mechanical pulverization of coarse grains of rock into finer grains. In such models, damage is balanced by “healing”, or the temperature and pressure-driven dynamic recrystallization of smaller grains into larger ones. If the reduction of grain size (damage) is intensely localized in a stagnant lid, an incipient crack in the mantle can turn into a full-blown rift, initiating plate tectonics.<ref name=Landuyt_etal_2008> Landuyt, W.; Bercovici, D.; Ricard, Y. (6 May 2008). "Plate generation and two-phase damage theory in a model of mantle convection". Geophysical Journal International 174 (3): 1065–1080. doi:10.1111/j.1365-246X.2008.03844.x. Retrieved 10 October 2014.</ref> Conversely, a high surface temperature will have more efficient lithospheric healing, which is another potential explanation for why Venus has a stagnant lid and Earth does not.<ref name=Foley_etal_2012 />

==Potential determining factors for Earth-like exoplanet geodynamic regimes==

==Potential determining factors for Earth-like exoplanet geodynamic regimes==