I will soon be leading the ERC-funded group Computational Petrology and Geochemistry at the Institute of Geological Sciences, University of Bern.
ERC Starting Grant project PROMOTING (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.
Numerical simulation of metamorphic reactions and fluid flows
The goal of this project is to understand how fluids affect the rock transformations in the Earth’s interior between 5 and 100 km depth using computer simulation. Within the framework of the project PROMOTING, we will develop new computer models of metamorphic systems and compare the results of computer simulation with geochemical data obtained on rocks from all around the world.
Figure 1: Numerical simulation of fluid flow within a 2D crustal section made of metasediments. The distribution of fluid (shown on the left) and fluid flows are controlled by the compaction pressure (right) of the rock matrix.
Figure 2: State-of-the-art petrological model for a typical metasediment along a prograde PT trajectory from 550 °C, 1.5 GPa and 620 °C – 2.4 GPa and comparison with the natural record. (a) Mod-box diagram showing the evolution of the mineral assemblage at each step along this trajectory. Note that garnet and fluid are fractionated. (b) Fluid released during prograde metamorphism in g of water per kg of rock. (c) Predicted compositional zoning of a single crystal of garnet across an equatorial section. (d) Compositional map of a garnet porphyroblast in a metasediment involved in the Alpine subduction. The maps are assumed to show the compositional zoning across a near-equatorial section.
Several Master, PhD and Postdoc positions will be advertised here soon
- Dr. Nicolas Riel (University of Mainz)
- Prof. Dr. Mahyra Tedeschi (Federal University of Minas Gerais)