Redox conditions in subducted oceanic crust from the Fe oxidation state of lawsonite and epidote

The main goal of this project is to evaluate redox conditions in the hydrous silicate minerals lawsonite and epidote because they are key components of the planetary system for (re)cycling volatiles and other elements via subduction and are sources and sinks of redox-sensitive elements involved in fluid-rock reactions. Although typically assumed to contain only Fe3+, Fe K-edge micro-XANES analyses at BM 23 in 2023 showed that lawsonite may contain substantial Fe2+. This leads to questions about what controls Fe oxidation state in lawsonite and how common Fe2+-bearing lawsonite is. This can be addressed with a suite of samples from different subduction zones that represent a range of pressure-temperature conditions and chemical environments. Further we will try to map out oxidation state changes during different crystal growth stages within one sample