scholarly journals A new hydrous silicate, a water reservoir, in the upper part of the lower mantle

1997 ◽  
Vol 24 (9) ◽  
pp. 1047-1050 ◽  
Author(s):  
Eiji Ohtani ◽  
Hiroki Mizobata ◽  
Yasuhiro Kudoh ◽  
Toshiro Nagase ◽  
Haruo Arashi ◽  
...  
Keyword(s):  
Lower Mantle ◽  
Water Reservoir ◽  
Hydrous Silicate

scholarly journals Evidence for the stability of ultrahydrous stishovite in Earth’s lower mantle

2019 ◽  
Vol 117 (1) ◽  
pp. 184-189 ◽  
Author(s):  
Yanhao Lin ◽  
Qingyang Hu ◽  
Yue Meng ◽  
Michael Walter ◽  
Ho-Kwang Mao
Keyword(s):  
Transition Zone ◽  
Lower Mantle ◽  
Water Reservoir ◽  
Weight Percent ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Components ◽  
The Stability ◽  
Stability Of Water

The distribution and transportation of water in Earth’s interior depends on the stability of water-bearing phases. The transition zone in Earth’s mantle is generally accepted as an important potential water reservoir because its main constituents, wadsleyite and ringwoodite, can incorporate weight percent levels of H2O in their structures at mantle temperatures. The extent to which water can be transported beyond the transition zone deeper into the mantle depends on the water carrying capacity of minerals stable in subducted lithosphere. Stishovite is one of the major mineral components in subducting oceanic crust, yet the capacity of stishovite to incorporate water beyond at lower mantle conditions remains speculative. In this study, we combine in situ laser heating with synchrotron X-ray diffraction to show that the unit cell volume of stishovite synthesized under hydrous conditions is ∼2.3 to 5.0% greater than that of anhydrous stishovite at pressures of ∼27 to 58 GPa and temperatures of 1,240 to 1,835 K. Our results indicate that stishovite, even at temperatures along a mantle geotherm, can potentially incorporate weight percent levels of H2O in its crystal structure and has the potential to be a key phase for transporting and storing water in the lower mantle.

scholarly journals Neutron diffraction study of hydrous phase G: Hydrogen in the lower mantle hydrous silicate, phase G

2001 ◽  
Vol 28 (20) ◽  
pp. 3987-3990 ◽  
Author(s):  
Akio Suzuki ◽  
Eiji Ohtani ◽  
Tadashi Kondo ◽  
Takahiro Kuribayashi ◽  
Nobuo Niimura ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Diffraction Study ◽  
Lower Mantle ◽  
Neutron Diffraction Study ◽  
Silicate Phase ◽  
Hydrous Silicate ◽  
Hydrous Phase

Lower-mantle water reservoir implied by the extreme stability of a hydrous aluminosilicate

2014 ◽  
Vol 8 (1) ◽  
pp. 75-79 ◽  
Author(s):  
Martha G. Pamato ◽  
Robert Myhill ◽  
Tiziana Boffa Ballaran ◽  
Daniel J. Frost ◽  
Florian Heidelbach ◽  
...  
Keyword(s):  
Lower Mantle ◽  
Water Reservoir ◽  
Extreme Stability

Phases and electrical conductivity of a hydrous silicate assemblage at lower-mantle conditions

Nature ◽  
1991 ◽  
Vol 350 (6316) ◽  
pp. 332-334 ◽  
Author(s):  
Xiaoyuan Li ◽  
Raymond Jeanloz
Keyword(s):  
Electrical Conductivity ◽  
Lower Mantle ◽  
Hydrous Silicate

scholarly journals Deep lower-mantle water reservoir implied by the stability of a mixed-valence hydrous iron-rich oxide

2021 ◽  
Author(s):  
Lu Liu ◽  
Ziqiang Yang ◽  
Hongsheng Yuan ◽  
Yue Meng ◽  
Nico Giordano ◽  
...  
Keyword(s):  
Lower Mantle ◽  
Hexagonal Phase ◽  
Mixed Valence ◽  
Water Reservoir ◽  
Stability Field ◽  
Recycled Water ◽  
Potential Source ◽  
Recovered Sample ◽  
The Stability ◽  
Water Contents

Abstract The lower mantle, containing both primordial and recycled water, is the most massive potential water reservoir in the Earth. Geophysical and geochemical evidence combined have suggested that the largest heterogeneities in the deep lower mantle may serve as primitive deep-mantle reservoirs hosting a variety of incompatible species including hydrogen. To understand water storage in the deep lower mantle, we conducted experiments in the Fe-O-H, Fe-Al-O-H and Fe-Al-Mg-Si-O-H systems under high pressure-temperature (P-T) conditions, and discovered a previously unknown hexagonal phase (referred to as “H1-phase”) in all the systems. The single-crystal structure of the H1-phase was determined at 79 GPa with a unit-cell of a=10.022(2 )Å and c=2.6121(9) Å and the space group of P63/m, and its composition was obtained as Fe12.76O18H3.7 combining the structure determination and chemical analysis on the recovered sample. More importantly, about 20 mol% of MgO, Al2O3 and SiO2 can be incorporated into the H1-phase in a realistic mantle system Fe-Al-Mg-Si-O-H and its stability field is extended to at least 2400 km along a normal geotherm, implying that the H1-phase can store primordial water in the deepest lower mantle. Therefore, plume-generation zones originated from the deepest lower mantle provide a potential source for higher water contents in basalts associated with mantle plume components.

scholarly journals Discovery of a hexagonal ultradense hydrous phase in (Fe,Al)OOH

2018 ◽  
Vol 115 (12) ◽  
pp. 2908-2911 ◽  
Author(s):  
Li Zhang ◽  
Hongsheng Yuan ◽  
Yue Meng ◽  
Ho-kwang Mao
Keyword(s):  
High Pressure ◽  
Lower Mantle ◽  
Hexagonal Phase ◽  
Hexagonal Lattice ◽  
Water Reservoir ◽  
Type Structure ◽  
X Ray Diffraction ◽  
Hydrous Minerals ◽  
X Ray ◽  
Hydrous Phase

A deep lower-mantle (DLM) water reservoir depends on availability of hydrous minerals which can store and transport water into the DLM without dehydration. Recent discoveries found hydrous phases AlOOH (Z = 2) with a CaCl2-type structure and FeOOH (Z = 4) with a cubic pyrite-type structure stable under the high-pressure–temperature (P-T) conditions of the DLM. Our experiments at 107–136 GPa and 2,400 K have further demonstrated that (Fe,Al)OOH is stabilized in a hexagonal lattice. By combining powder X-ray-diffraction techniques with multigrain indexation, we are able to determine this hexagonal hydrous phase with a = 10.5803(6) Å and c = 2.5897(3) Å at 110 GPa. Hexagonal (Fe,Al)OOH can transform to the cubic pyrite structure at low T with the same density. The hexagonal phase can be formed when δ-AlOOH incorporates FeOOH produced by reaction between water and Fe, which may store a substantial quantity of water in the DLM.

Stability of hydrous silicate at high pressures and water transport to the deep lower mantle

2014 ◽  
Vol 7 (3) ◽  
pp. 224-227 ◽  
Author(s):  
M. Nishi ◽  
T. Irifune ◽  
J. Tsuchiya ◽  
Y. Tange ◽  
Y. Nishihara ◽  
...  
Keyword(s):  
Water Transport ◽  
Lower Mantle ◽  
High Pressures ◽  
Hydrous Silicate
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