Ferrous Iron Under Oxygen-Rich Conditions in the Deep Mantle.

ABSTRACT: Recent experiments have demonstrated the existence of previously unknown iron oxides at high pressure and temperature including newly discovered pyrite-type FeO₂ and FeO₂H_x phases stable at deep terrestrial lower mantle pressures and temperatures. In the present study, we probed the iron oxidation state in high-pressure transformation products of Fe³⁺OOH goethite by in situ X-ray absorption spectroscopy in laser-heated diamond-anvil cell. At pressures and temperatures of ~91 GPa and 1,500-2,350 K, respectively, that is, in the previously reported stability field of FeO₂H_x, a measured shift of -3.3 ± 0.1 eV of the Fe K-edge demonstrates that iron has turned from Fe³⁺ to Fe²⁺. We interpret this reductive

SUBMITTER: Boulard E 

PROVIDER: S-EPMC6472328 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature