Tohoku University · Earth and Planetary Sciences
Professor Eiji Ohtani's research lab specializes in mineral physics and geochemistry, focusing on the behavior of water and hydrogen in Earth's deep interior. The lab investigates the distribution, transport, and storage of water in the mantle, particularly in the transition zone and lower mantle, using geophysical, mineralogical, and isotopic data. Key research directions include deep dehydration processes in subducting slabs, the formation of hydrous magmas, and the geochemical signatures of deep water cycling. The lab also explores the role of water in influencing mantle dynamics, seismic anomalies, and the long-term evolution of Earth's interior.
Figures are computed from collected data and may differ slightly.
Research Article| January 01, 2005 Water in the Mantle Eiji Ohtani Eiji Ohtani 1Institute of Mineralogy, Petrology, and Economic Geology, Tohoku University, Sendai 980-8578, Japan E-mail: ohtani@mail.tains.tohoku.ac.jp Search for other works by this author on: GSW Google Scholar Elements (2005) 1 (1): 25–30. https://doi.org/10.2113/gselements.1.1.25 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Ic
Geophysical observations suggest that the transition zone is wet locally. Continental and oceanic sediment components together with the basaltic and peridotitic components might be transported and accumulated in the transition zone. Low-velocity anomalies at the upper mantle-transition zone boundary might be caused by the existence of dense hydrous magmas. Water can be carried farther into the lower mantle by the slabs. The anomalous Q and shear wave regions locating at the uppermost part of the
Hydrogen and deuterium isotopic evidence indicates that the source of terrestrial water was mostly meteorites, with additional influx from nebula gas during accretion. There are two Earth models, with large (7–12 ocean masses) and small (1–4 ocean masses) water budgets that can explain the geochemical, cosmochemical, and geological observations. Geophysical and mineral physics data indicate that the upper and lower mantles are generally dry, whereas the mantle transition zone is wetter, with het
Abstract Mineral physics data related to the deep dehydration of stagnant slabs are summarized. The hydrogen diffusion in minerals of the mantle transition zone is not fast enough to homogenize the transition zone on the geological time scale, and hydrogen is expected to be unevenly distributed there. The hydrous fluid formed in the transition zone tends to percolate into shallower depths to form gravitationally stable hydrous magmas at the base of the upper mantle. We need further studies on th
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