Fluorine control on lithium enrichment during metapelite partial melting and reactive melt transport

• Applicant: Nicolas Riel, Ph.D.
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 585304910

Although lithium is essential for modern technologies, the geological processes that concentrate lithium in magmas are still not well understood, particularly the role played by fluorine. This project aims to understand how lithium becomes enriched in melts produced from fluorine-rich sedimentary rocks during partial melting in the Earth’s crust, and how this enrichment may increase as magmas migrate through surrounding rocks. To address this problem, the project will improve existing computer models that simulate how rocks melt and how chemical elements are distributed between solid minerals and molten material under changing temperature and pressure conditions. Current models successfully describe many geological systems but do not explicitly account for fluorine, even though it strongly affects melting behaviour, melt viscosity, and the distribution of elements such as lithium. The project will therefore upgrade modelling software to allow more flexible and efficient calculations and to incorporate fluorine as an active chemical component. Experimental data will be used to improve how fluorine-bearing minerals and melts are represented in the models. This includes extending existing models for common minerals and silicate melts to include fluorine, as well as developing a new model for the fluorine-rich mineral topaz. These improvements will ensure that the models are internally consistent and accurately reflect laboratory observations. Once the improved models are established, they will be used to simulate how lithium enters melts during partial melting of fluorine-rich sedimentary rocks. The project will then go beyond static melting calculations by modelling how melts move through the crust and interact with surrounding rocks. These simulations will show how melt migration, chemical reactions, and focused flow can further increase lithium concentrations. By combining improved thermodynamic modelling with simulations of melt transport, this project will provide the first quantitative picture of how fluorine-rich source rocks generate lithium-rich magmas. The results will help explain the formation of lithium-rich magmatic systems, such as those associated with pegmatites, and will improve our understanding of geological processes relevant to the exploration of lithium resources. All modelling tools and data developed in the project will be made openly available to support future research.

• DFG Programme: Research Grants