2026-08-31 岡山大学,愛媛大学,広島大学,帝京科学大学,京都大学,高輝度光科学研究センター
図1．沈み込むプレート内の水の分布。
＜関連情報＞
- https://www.okayama-u.ac.jp/tp/release/release_id1600.html
- https://www.nature.com/articles/s43247-026-03856-7
下部マントル条件下におけるダベマオアイトへの水の取り込みは限定的である Limited water incorporation in davemaoite under lower-mantle conditions
Takayuki Ishii,Goru Takaichi,Yu Nishihara,Kyoko N. Matsukage,Shoichi Itoh,Yanhao Lin,Tetsuo Irifune,Daijo Ikuta,Bin Zhao,Dilan H. F. Diyalanthonige,Noriyoshi Tsujino,Sho Kakizawa & Yuji Higo
Communications Earth & Environment Published:24 July 2026
DOI:https://doi.org/10.1038/s43247-026-03856-7 Early provide
Abstract
Water storage in Earth’s mantle impacts its physical and chemical properties, yet the capacity of the lower mantle to host water remains poorly constrained. While the transition zone is a major reservoir, the dominant lower-mantle minerals bridgmanite and ferropericlase exhibit limited water solubility, and the role of davemaoite (CaSiO3-perovskite) remains uncertain due to experimental challenges. Here we report in-situ lattice-volume measurements of davemaoite synthesized under dry and hydrous conditions up to 30 GPa and 2100 K using advanced multi-anvil techniques. At lower-mantle temperatures, hydration produces only a marginal volume reduction, indicating that water incorporation is limited to trace levels rather than the substantial amounts suggested previously. We also find no clear evidence for the tetragonal structure regardless of hydration. These results indicate that davemaoite stores limited water in the peridotitic mantle, implying that subducted crustal materials such as basaltic crust containing hydrous silica phases could dominate deep-lower mantle water storage.
