Pierre Lanari, Oberassistant à l'Institute of Geological Sciences de l'Université de Bern donnera, en salle E112, un séminaire titré: "New horizons and computer tools for characterising and modelling crustal metamorphism".
The astonishing progress of personal computer technology in the past 30 years as well as the availability of thermodynamic data and modeling programs have revolutionized our ability to investigate and quantify metamorphic processes. Equilibrium thermodynamics has played a central role in this evolution, providing simultaneously a physico‐chemical framework and efficient modeling strategies to calculate mineral stability relations in the Earth’s lithosphere (and beyond) as well as thermobarometric results.
In this talk, I first describe a new modeling strategy based on iterative thermodynamic models, integrated with quantitative compositional mapping. This technique provides a powerful alternative to the traditional modeling tools and permits to use local bulk composition for testing the assumption of local equilibrium in rocks that were not fully re-equilibrated during their metamorphic history. In addition, I present the first internally consistent database for oxygen fractionation factors between minerals and an aqueous fluid. This database can be applied in a thermodynamic framework to simulate the evolution of δ18O in minerals through their metamorphic history. This strategy enhances our ability to reconstruct the invisible path of fluids in exhumed metamorphic terrains and to investigate samples that experienced complex fluid-rock interactions.
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