Iron disproportionation in peridotite fragments from the mantle transition zone

作者：Fabin Pan, Xiang Wu, Chao Wang, Yanfei Zhang, Yiping Yang, Xiaobo He, Chong Wei Jin, Lian Zhou, Hongfei Zhang, Hongping He, Junfeng Zhang · 发表于：Nature Communications · 年份：2025 · DOI：10.1038/s41467-025-60566-y · 被引用次数：5 · 研究领域：Geological and Geochemical Analysis、High-pressure geophysics and materials、earthquake and tectonic studies

Abstract Previous high-temperature-pressure experiments predicted metallic iron’s potential presence in the deep mantle below 250 km, arising from ferrous disproportionation in silicates, which could profoundly impact the redox environment and physicochemical properties. However, direct natural petrological evidence has been lacking, except scant clues like Fe-alloy inclusions in ultradeep diamonds. Here we present peridotite fragments, found in Cenozoic basalts from eastern China, containing decomposed Na-rich majoritic garnets (from depths of 410-550 km) and olivine with Fe 0 -spinel-bearing inclusions, likely originated from retrograded wadsleyite/ringwoodite. Enriched Zn-Sr isotopic compositions of the decomposed garnet indicate an origin associated with the stagnant Pacific slab in the mantle transition zone. Disproportionation of iron is evidenced by widely distributed submicron-sized spherical Fe-Ni alloys and Fe 3+ -rich (Fe 3+ /ΣFe = 0.35-0.40) olivine. These findings provide compelling evidence for recycling of stagnant slab components in the eastern Asia big mantle wedge (BMW), and iron disproportionation in the deep mantle.