Experimental and Observational Constraints on Halogen Behavior at Depth

Halogens are volatile elements present in trace amounts in the Earth’s crust, mantle, and core. They show volatile behavior and tend to be incompatible except for fluorine, which makes them key tracers of fluid-mediated and/or melt-mediated chemical transport processes. Even small quantities of halogens can profoundly affect many physicochemical processes such as melt viscosity, the temperature stability of mineral phases, the behavior of trace elements in aqueous fluids, or the composition of the atmosphere through magma degassing. Experiments allow us to simulate deep-Earth conditions. A comparison of experimental results with natural rocks helps us to unravel the role and behavior of halogens in the Earth’s interior.