A schematic of an open-system mantle melting and melt migration process, as modeled by Ozawa [2001] and implemented in the new GUI. As (a) an assemblage of minerals upwells and (b) crosses the solidus and begins melting, the melt is retained along grain boundaries up to a certain critical melt fraction f c . Then (c) melt begins to migrate vertically (making it an open system), and the model tracks both the instantaneous melt in equilibrium with the residue and the accumulated melts reaching the top of the column. Finally, as the lithosphere thickens and the system cools towards the solidus again, the trapped melt may be (d) separated and added to the accumulated melt or frozen in place to yield a partly refertilized residual peridotite. Credit: Nishio et al. [2026] , Figure 1