2025/11/04 by Wang, Zifan, He, Yu, Mao, Ho-kwang +1
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · Physics and Astronomy · #Electrical resistivity and conductivity #FOS: Physical sciences #Geomagnetism and Paleomagnetism Studies #Geophysics (physics.geo-ph) #High-pressure geophysics and materials #Hydrogen #Magnesium #Mantle (geology) #Planetary Science and Exploration #Ringwoodite #Silicate #Transition zone
paper · open access · doi:10.48550/arxiv.2511.02416
published in arXiv (Cornell University) (Cornell University)
openalex publication_date 2025/11/04 · openalex created_date 2025/11/06 · openalex updated_date 2026/07/28
The Earth's mantle transition zone (MTZ) is widely recognized as a major water reservoir, exerting significant influence on the planet's water budget and deep cycling processes. Here, we employ crystal structure prediction and first-principles calculations to identify a series of stable hydrous magnesium silicate phases under transition zone conditions. Our results reveal a pressure-induced hydrogen substitution mechanism in wadsleyite, where H+ preferentially migrates from Mg2+ sites to Si4+ sites near 410 km depth. This transformation leads to a substantial decrease in electrical conductivity, consistent with geophysical observations. We estimate the water content in the MTZ to be approximately 1.6 wt%, aligning with seismic and conductivity constraints. Furthermore, using machine learning-enhanced molecular dynamics, we discover double superionicity in hydrous wadsleyite and ringwoodite at temperatures exceeding 2000 K, wherein both H+ and Mg2+ exhibit high ionic mobility. This dual-ion superionic state has potentially profound implications for mass transport, electrical conductivity, and magnetic dynamo generation in rocky super-Earth exoplanets.