TY - JOUR
T1 - Stability of a hydrous δ-phase, AlOOH-MgSiO2(OH)2, and a mechanism for water transport into the base of lower mantle
AU - Ohira, Itaru
AU - Ohtani, Eiji
AU - Sakai, Takeshi
AU - Miyahara, Masaaki
AU - Hirao, Naohisa
AU - Ohishi, Yasuo
AU - Nishijima, Masahiko
N1 - Funding Information:
We thank A. Suzuki, M. Murakami and T. Sakamaki for useful discussions during this work. We also thank S. Kamada for his experimental assistance at SPring-8. This work was supported by KAKENHI Grant of Japan Society for the Promotion of Science (JSPS), Grant numbers 18194009 , 2200002 awarded to E.O. This work was also supported partly by the Ministry of Education and Science of Russian Federation , project 14.B25.31.0032 to E.O. This work was conducted as part of the Global Center of Excellence program “Global Education and Research Center for Earth and Planetary Dynamics”. Part of this work was supported by the “Nanotechnology Support Project (Nanotech Japan)” of the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), Japan.
PY - 2014/9/1
Y1 - 2014/9/1
N2 - The global water cycle in the Earth is one of the most important issues in geodynamics, because water can affect the physical and rheological properties of the mantle. However, it is still a matter of debate whether water can be transported into the lower mantle and core. Here we report a new reaction between aluminous perovskite and water to form alumina-depleted perovskite and hydrous δ-phase AlOOH-MgSiO2(OH)2 along the mantle geotherm in the lower mantle. Chemical analysis of the coexisting phases showed that the perovskite and post-perovskite phases were depleted in Al2O3, whereas hydrous δ-phase contains at least 44 mol% of MgSiO2(OH)2 component at 68 GPa and 2010 K, and 23 mol% of this component at 128 GPa and 2190 K. The present experiments revealed that hydrous δ-phase AlOOH-MgSiO2(OH)2 can coexist with alumina-depleted MgSiO3 perovskite or post-perovskite under the lower mantle conditions along the slab geotherm. Thus this hydrous phase in the slabs can transport water into the base of the lower mantle.
AB - The global water cycle in the Earth is one of the most important issues in geodynamics, because water can affect the physical and rheological properties of the mantle. However, it is still a matter of debate whether water can be transported into the lower mantle and core. Here we report a new reaction between aluminous perovskite and water to form alumina-depleted perovskite and hydrous δ-phase AlOOH-MgSiO2(OH)2 along the mantle geotherm in the lower mantle. Chemical analysis of the coexisting phases showed that the perovskite and post-perovskite phases were depleted in Al2O3, whereas hydrous δ-phase contains at least 44 mol% of MgSiO2(OH)2 component at 68 GPa and 2010 K, and 23 mol% of this component at 128 GPa and 2190 K. The present experiments revealed that hydrous δ-phase AlOOH-MgSiO2(OH)2 can coexist with alumina-depleted MgSiO3 perovskite or post-perovskite under the lower mantle conditions along the slab geotherm. Thus this hydrous phase in the slabs can transport water into the base of the lower mantle.
KW - Aluminous perovskite
KW - Hydrous phase H
KW - Hydrous δ-phase
KW - Lower mantle
KW - Post-perovskite
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U2 - 10.1016/j.epsl.2014.05.059
DO - 10.1016/j.epsl.2014.05.059
M3 - Article
AN - SCOPUS:84902255023
VL - 401
SP - 12
EP - 17
JO - Earth and Planetary Sciences Letters
JF - Earth and Planetary Sciences Letters
SN - 0012-821X
ER -