Deciphering the duration of fluid-rock interaction

• Applicant: Professor Dr. Timm John
• Subject Area: Mineralogy, Petrology and Geochemistry
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 513982794

Enormous portions of the Earth’s crystalline lithosphere are being (and have been) chemically modified by fluid-driven mineral reactions. These reactions drive several consequential fluid-mediated rock transformation processes, including those that govern the stability of mountain belts, the formation of hydrothermal mineral deposits and the sequestration of anthropogenic CO2, and these processes can also lead to dramatic effects such as megathrust earthquakes at plate interfaces. However, despite the unique significance of fluid-rock interactions for the dynamic evolution of the Earth’s crust and Earth’s chemical reservoirs, the timescales of these interactions remain essentially unconstrained. To date, the durations of fluid-rock interactions, as retained in the rock record, have been assessed according to chronometric modelling, which we and others have, so far, considered to correctly determine these durations. However, no studies have verified this: The results of chronometric modelling have not been compared to those of experimental studies, because no such experiments have been performed. Therefore, the main goal of this project is to develop experiments to test whether chronometric modelling can reliably determine the duration of fluid-rock interactions. Our proposed breakthrough research lies in applying a highly innovative experimental setup to identify and verify or, wherever needed, modify the input parameters and the assumptions underlying the numerical chronometric modelling approach. In doing so, the project will also lead to a better understanding of key processes underlying the interaction between fluid and rocks, such as how transport occurs at reactive grain boundaries, how the transient properties of porosity and permeability evolve and how grain boundary-mediated transport contributes to the effective bulk reactivity and transportability of polycrystalline materials.

• DFG Programme: Reinhart Koselleck Projects
• Co-Investigators: Dr. Johannes C. Vrijmoed; Professor Dr. Max Wilke