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Stability of hydrous phase H MgSiO 4 H 2 under lower mantle conditions
Author(s) -
Ohtani Eiji,
Amaike Yohei,
Kamada Seiji,
Sakamaki Tatsuya,
Hirao Naohisa
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl061690
Subject(s) - mantle (geology) , geology , phase (matter) , dissolution , mineralogy , thermodynamics , analytical chemistry (journal) , geochemistry , chemistry , environmental chemistry , physics , organic chemistry
We report the stability field of a new high‐pressure hydrous phase, phase H MgSiO 4 H 2 , and its implications for water transport into the deep lower mantle. We observed the existence of hydrous phase H at pressures around 50 GPa, and this phase was stable up to 60 GPa. Our results, together with those of previous works, indicate that pure phase H MgSiO 4 H 2 has a very narrow stability field in the pressure range 35 < P < 60 GPa, equivalent to the uppermost part of the lower mantle. The stability field expands significantly toward higher pressures and temperatures on dissolution of the hydrous AlOOH component. The hydrous phase H‐phase δ solid solution (aluminous phase H), (MgSi,Al 2 )O 4 H 2 , is potentially the most important hydrous phase present under the deep lower mantle conditions.