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Geodynamics of terrestrial exoplanets
The discovery of extrasolar Earth-sized planets has spurred inquiry regarding their potential for habitability. One of the generally agreed-upon (Noack and Breuer and references within)〔 requirements for a life-sustaining planet is a mobile, fractured lithosphere cyclically recycled into a vigorously convecting mantle, commonly known as plate tectonics. Plate tectonics provide a means of geochemical regulation of atmospheric particulates, as well as sequestration of carbon. This prevents “runaway greenhouse” scenarios that can result in inhospitable surface temperatures and vaporization of liquid surface water.〔 There is not a clear academic consensus on whether Earth-like exoplanets have plate tectonics, but it is widely thought that the likelihood of plate tectonics on an Earth-like exoplanet is a function of planetary radius, initial temperature upon coalescence, insolation, and presence or absence of liquid-phase surface water.
==Potential exoplanet geodynamic regimes==
In order to characterize the geodynamic regime of an Earth-like exoplanet, the basic assumption is made that such a planet is Earth-like or “rocky”. This implies a three-layer stratigraphy of (from center to surface) a partially molten iron core, a silicate mantle that convects over geologic timescales, and a relatively cold, brittle silicate lithosphere. Within these parameters, the geodynamic regime at a given time point in the planet’s history is likely to fall within one of three categories:
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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