A Graphical User Interface Application to Model Open‐System Melting in the Upper Mantle

Abstract

The mantle partial melting process is crucial for the physicochemical evolution of the Earth's upper mantle and the generation of mafic crust. The open‐system melting model incorporates continuous melt segregation, interaction with melts or fluids, and crystallization of trapped melt and therefore provides a comprehensive model for simulating mantle melting. Despite its broad capability, the model is difficult to apply because it requires complex parameter settings. We developed osm.R , a graphical user interface application that enables users to conduct open‐system melting models without coding. Several tools within osm.R support both beginners and experienced users, making the model accessible while maintaining functionality. The application can simulate trace‐element behavior in residues and melts across a wide range of melting conditions and can also perform best‐fit estimation against observed data to constrain melting processes. Applying osm.R to clinopyroxene from abyssal peridotites confirms that the open‐system melting model can reproduce natural clinopyroxene REE patterns by optimizing the degree of melting, critical melt fraction, and melt influx rate. The melting degrees estimated by simultaneously constraining critical melt fraction and melt influx rate are more reliable than those calculated from Yb contents in clinopyroxene by assuming fractional melting. The systematic change in the critical melt fraction with increasing melting degree may reflect progressive changes in melt separation efficiency beneath mid‐ocean ridges. This highlights how osm.R strengthens the application of open‐system melting models and improves our understanding of mantle melting in open systems.