Inevitability of Plate Tectonics on Super-Earths

TL;DR

This paper argues that super-Earths are highly likely to have plate tectonics due to increased shear stress and decreased plate thickness with planetary mass, which supports their potential habitability.

Contribution

It demonstrates that super-Earths will almost certainly exhibit plate tectonics, extending the understanding of planetary dynamics beyond Earth.

Findings

Super-Earths have increased shear stress facilitating plate movement.

Decreased plate thickness in super-Earths promotes subduction.

Plate tectonics is likely on super-Earths even if they are dry.

Abstract

The recent discovery of super-Earths (masses less or equal to 10 earth-masses) has initiated a discussion about conditions for habitable worlds. Among these is the mode of convection, which influences a planet's thermal evolution and surface conditions. On Earth, plate tectonics has been proposed as a necessary condition for life. Here we show, that super-Earths will also have plate tectonics. We demonstrate that as planetary mass increases, the shear stress available to overcome resistance to plate motion increases while the plate thickness decreases, thereby enhancing plate weakness. These effects contribute favorably to the subduction of the lithosphere, an essential component of plate tectonics. Moreover, uncertainties in achieving plate tectonics in the one earth-mass regime disappear as mass increases: super-Earths, even if dry, will exhibit plate tectonic behaviour.