Extending (Garnet) Diffusion Modelling into Multidimensional Domains

The variation in element concentrations within a mineral play a critical role in understanding the evolution of geological margins over time. Diffusion is a process that alters element concentrations during crystal growth and subsequent cooling, with modelling of this process primarily conducted in one-dimension (1D), significantly contributing to understanding the thermal and tectonic evolution of various igneous and metamorphic regions. However, the complexity of geological systems requires a more detailed approach encapsulating the multidimensional nature of mineral evolution. We present the initial developments of diffusion modelling, extending from 1D models to two-dimensional (2D) and three-dimensional (3D) modelling of garnet diffusion using the Underworld code. These models are designed to better constrain geological settings where garnet diffusion occurs, concentrating on the growth and extraction of the mineral from various bulk rock compositions. 2D and 3D models are compared to previously published work to validate the development of the models. Furthermore, the implications of these models for geochronological and petrological interpretations are explored, highlighting their potential to provide further insights into metamorphic processes when compared to 1D models. Future work will focus on the anisotropic properties of the garnet, including fast diffusion pathways within the mineral, as well as anisotropic properties of the rock itself, due to varying diffusion coefficients across minerals. This research paves the way for a more comprehensive understanding of diffusion in rocks, offering a robust tool for the community to unravel the complex history recorded in metamorphic rocks and enhance the accuracy of thermobarometric estimations. Through these new tools, we aim to provide better insights into the evolution of geological margins over time.