Studies of terrestrial exoplanet thermo-chemical-magmatic mantle and lithosphere dynamics and evolution

Terrestrial exoplanets, ranging in size up to approximately twice Earth-size (10 Earth masses), may have a range of characteristics that are not found in solar system planets, including but not limited to: larger size, different bulk composition (possibly resulting in being core-less), being tidally-locked to their host star, and being covered by water layers. Larger size has been proposed to result in sluggish deep-mantle convection and also (for stagnant-lid exoplanets) lower magmatism and outgassing, but internal differentiation is still expected to take place. Different bulk composition may lead to different viscosity (among other physical properties), modified melting behaviour and different core size (including the possibility of having no core). Tidally-locked exoplanets likely have hemispherical tectonics and internal structures, but the asymmetry would be reduced if they are continuously reorienting due to true polar wander. We are pursuing a range of studies investigating most of these different aspects using thermo-chemical convection models that include self-consistent lithospheric dynamics, partial melting and crustal production, using the code StagYY. Some of these studies are presented elsewhere at this meeting; this presentation will focus on additional interesting results.