other models, focused on the fault strength integral to subduction initiation, have come to the opposite conclusion that plate tectonics are unlikely [e.g. @ONei07]. More general models find the tectonic state of a super-Earth is a function of planet size, incident solar radiation, and atmospheric composition [e.g. @Fole12]. Each of these models, however, simply scale the Earth in composition and structure and sought only to understand how changes in the physical parameters of a planet affected tectonics, rather than address the much more complicated (and data-lacking) question of how planet chemical diversity affects tectonics.

An alternate approach is to assess *probabilistically*, rather than *definitively*, the relative likelihood of tectonics on exoplanets in individual systems by examining the effect of planetary chemistry on plate tectonics [@Unte14; @Unte15; @Stam16]. In this study, we quantify the effect of planet composition on a vital aspect of sustaining plate tectonics on terrestrial planets over billion year timescales: the sinking forces of the exocrust into a planet’s mantle. We therefore address a minimum criterion for plate tectonics: whether or not the surface crusts sink into the mantle due to buoyancy forces arising from thermal and chemical differences between the surface crust and the interior mantle. In 