Water in the mantle transition zone and the core-mantle boundary plays a key role in Earth’s stratification,volatile cycling,and core formation.If water transportation is actively running between the aforementioned l...Water in the mantle transition zone and the core-mantle boundary plays a key role in Earth’s stratification,volatile cycling,and core formation.If water transportation is actively running between the aforementioned layers,the lower mantle should contain water channels with distinctive seismic and/or electromagnetic signatures.Here,we investigated the electrical conductivity and sound velocity ofε-FeOOH up to 71 GPa and 1800 K and compared them with global tomography data.An abrupt threeorder jump of electrical conductivity was observed above 50 GPa,reaching 1.24(12)×10^(3)S/m at 61 GPa.Meanwhile,the longitudinal sound velocity dropped by 16.8%in response to the high-to-low spin transition of Fe^(3+).The high-conductivity and low-sound velocity ofε-FeOOH match the features of heterogenous scatterers in the mid-lower mantle.Such unique properties of hydrousε-FeOOH,or possibly other Fe-enriched phases can be detected as evidence of active water transportation in the mid-lower mantle.展开更多
基金supported by the Research Start-up Funds of Talents of Sichuan University (1082204112667)China Postdoctoral Science Foundation (18NZ021-0213216308)+6 种基金supported by Spanish Mineco Project (FIS2017-83295-P)supported by the Strategic Priority Research Program of Chinese Academy of Sciences (XDB41000000)supported by the China Academy of Engineering Physics Research Project (CX20210048)a Tencent Xplorer Prizepartially supported by the National Natural Science Foundation of China (42074098)the United Laboratory of High-pressure Physics and Earthquake Science (HPPES202001)the China Academy of Engineering Physics Joint Fund (U1530402)
文摘Water in the mantle transition zone and the core-mantle boundary plays a key role in Earth’s stratification,volatile cycling,and core formation.If water transportation is actively running between the aforementioned layers,the lower mantle should contain water channels with distinctive seismic and/or electromagnetic signatures.Here,we investigated the electrical conductivity and sound velocity ofε-FeOOH up to 71 GPa and 1800 K and compared them with global tomography data.An abrupt threeorder jump of electrical conductivity was observed above 50 GPa,reaching 1.24(12)×10^(3)S/m at 61 GPa.Meanwhile,the longitudinal sound velocity dropped by 16.8%in response to the high-to-low spin transition of Fe^(3+).The high-conductivity and low-sound velocity ofε-FeOOH match the features of heterogenous scatterers in the mid-lower mantle.Such unique properties of hydrousε-FeOOH,or possibly other Fe-enriched phases can be detected as evidence of active water transportation in the mid-lower mantle.
