Project (2024-2027, part-funding from UNIL)
Development of observation-driven thermodynamic models
Predictive petrological models based on equilibrium thermodynamics have become an important tool for simulating solid and liquid transformations in the Earth’s interior. For example, the successive transformations of minerals, fluids and/or melts can be predicted for pressure-temperature conditions corresponding to different tectonic, magmatic and metamorphic scenarios. These petrological models can also provide estimates of important properties of a planet’s interior, such as density or seismic velocities, which in the case of the Earth can be compared with geophysical observations. The use of petrological models now extends beyond the field of petrology, as they are commonly used in the wider geoscience and planetary science communities. However, these models are not yet fully integrated into complex physical and geophysical models because the calculation of the equilibrium state — by Gibbs free energy minimisation — is still relatively slow due to the complexity of the existing solution models. In addition, there is growing evidence in the literature that the existing models fail to reproduce some important trends in mineral composition observed both experimentally and in nature, for example along metamorphic field gradients outcropping in exhumed domains of continental crust. In this project, we are developing a general strategy to extract equilibrium natural data from metamorphic field gradients and a an open source inversion package that combines experimental and natural data to simultaneously optimise the thermodynamic properties of solution models.
ERC StG project (2020-2025)
PROgrade metamorphism MOdeling: a new petrochronological and compuTING framework – PROMOTING
Prograde metamorphism produces large amounts of fluids that have an important role for earthquake generation, arc magmatism, the growth of continental crust and for global geochemical cycles. Despite recent efforts, it remains challenging to recognize and quantify fluid fluxes in natural rocks and to model fluid pathways. The existing petrological modeling techniques are all based on the thermodynamic analysis of single rock types and neglect the chemical changes caused by fluid expulsion and the possible interactions with other rocks. The next frontier in metamorphic petrology is therefore to move our modeling capabilities from an isolated single rock system to an open and multi-rock system, in which fluids can flow in, react and flow out. This concept introduces several challenges from the quantification of fluid-rock interactions in natural samples to the integration of aqueous thermodynamics and fluid dynamics in the petrological models. Based on the developments of high-resolution techniques such as quantitative compositional mapping, I have demonstrated that the petrological models can be inverted to quantify prograde metamorphism based on preserved mineral relics that partially re-equilibrated in the presence of fluids. The primary objective of PROMOTING is to develop a brand-new framework for petrological modeling of fluid-rock interactions in different, coupled rock types during prograde metamorphism. The models will be calibrated on two key tectonic settings that shaped Earth: subduction of oceanic crust and differentiation of the continental crust. A cutting-edge petrochronological strategy is required to identify at which conditions and when fluid-rock interactions occurred in natural rocks. The outcomes of this project will not only form the basis for a new generation of models integrating element mobility from rock scale to crustal sections, but they will also bring new constraints to test the validity of the most advanced subduction models.
