subset of 89 stellar compositions that are within the internally consistent MELTS database [@Ghio02]. We find a chemical buoyancy of these systems ranges from $-10*10^{12}$ N m$^{-1}$ (sinks) to $3.6*10^{12}$ N m$^{-1}$ (floats).

Of terrestrial planets with compositions represented by the variation in both stellar datasets, 19% would produce exocrusts entirely buoyant than their BSP throughout the entire upper mantle ($F_{c} > 0$), and therefore unable to subduct (Figure \[fig:histogram\]). Furthermore, 61% of the Adibekyan sample and 41% of the *Kepler* sample produces plates more chemically buoyant than that of our model Earth ($F_{c} > F_{c-Earth}$; Figure \[fig:histogram\]) and therefore *less likely* to host plate tectonics than the Earth.

![Histograms of buoyancy forces calculated using our model for our sample of 609 @Adib12 stars (gray) and 89 **Kepler** planet hosts (purple) with compositions inside the MELTS database [@Ghio02]. Those modeled from stellar composition are shown in red. The buoyancy force and bulk composition of model Earth is shown as a light gray dashed line.[]{data-label="fig:histogram"}](Histogram.pdf){width=".6\linewidth"}

This variation in buoyancy forces is mainly caused by the enrichment of Si and alkali elements (Na, K) within the melt-extracted crust. Partial melting of typical mantle rocks leads to enrichment of silica and alkalis in 