资源环境科技发展态势分析平台

The thermal stability of hydrous minerals in Earth's deep interior is key to understanding the evolution and physicochemical states of the planet. The recently discovered pyrite-type (Py) FeO₂H_x (x≤1) phase, which can be transformed from α/ε-FeOOH at ∼80 GPa, is believed to be a crucial candidate to transport water and hydrogen to the lowermost mantle through subducting slabs. Here, we report the stability and decomposition of FeOOH by shock recovery experiments up to ∼70 GPa and ∼2750 K. The experimental results show that FeOOH partially decomposes to iron oxides Fe₂O₃ and Fe₃O₄ at 35-70 GPa and 1150-2750 K. Our study indicates that H₂O and O₂ are formed during the decomposition of FeOOH in subducting slabs. H₂O and O₂ released from FeOOH may have acted as sporadic sources for the Great Oxidation Event (GOE) and altered the physical and chemical properties of the surrounding mantle.