2026-08-12 –, Room 3
MovingBoundaryMinerals.jl (Stroh et al., 2025) is a Finite Element package to model diffusion-limited growth. The package combines grid refinement together with a moving boundary in order to resolve sharp gradients next to the interface of growing crystals. The moving boundary is treated via a thermodynamically-consistent diffusion solver. We provide benchmarks and examples that can be used in petrology and materials science.
Compositional concentration profiles across individual crystals or diffusion couples are largely determined by diffusion and growth processes. These two processes are particularly important during the formation of high-temperature rocks such as igneous and metamorphic rocks. The numerical simulation of concentration profiles in crystals is a widely used technique in various fields such as geospeedometry or diffusion chronometry. Compared to single crystals, coupled diffusion pairs yield tighter constraints on the experienced temperature and pressure ranges and thus provide additional information for our models. However, the numerical description of concentration profiles within diffusion couples is challenging due to the sharp compositional gradients. Discontinuities in concentration, which are related to the different mineral properties, commonly occur at the interface of two minerals and lead to technical implementation issues.
To address these issues, we have developed the Finite Element (FE) package MovingBoundaryMinerals.jl (Stroh et al., 2025) that can calculate the evolution of concentration profiles in diffusion couples with moving interfaces. Within this package, we consider diffusion-limited growth. Grid refinement allows to resolve changes near the interface with a higher resolution. An adaptive grid enables the accurate reproduction of rapid concentration changes and discontinuities. Our code can be applied to various examples of single crystals or diffusion couples, integrating any combination of growth, diffusion, and temperature dependency. Additionally, it is possible to calculate concentration profiles based on the thermodynamically-constrained, Stefan-Interface condition. Our code is benchmarked against analytical solutions for limiting cases. Results from our models can be used in petrology and geodynamic applications to provide tighter constraints concerning the pressure and temperature evolution of magmatic and metamorphic mineral assemblages.
Reference
Stroh, A., Aellig, P. S., and Moulas, E.: Numerical modelling of diffusion-limited mineral growth for geospeedometry applications, EGUsphere, 1–37, https://doi.org/10.5194/egusphere-2025-2511, 2025.
Annalena Stroh is a PhD student in the Metamorphic Processes group (Geosciences) at JGU Mainz. Her research focuses on evaluating timescales in crystal growth and diffusion processes using numerical models.
Pascal Aellig is a PhD student in computational geosciences at the Johannes Gutenberg University Mainz. He co-develops JustRelax.jl and other packages in the framework of geodynamics with the focus on the evolution of magmatic systems of various scales.