Tetrahedral ferric iron in oxidized hydrous wadsleyite

Smyth, Joseph R.; Bolfan-Casanova, Nathalie; Avignant, D.; El‐Ghozzi, Malika; Hirner, Sarah M.

doi:10.2138/am.2014.4520

Cited by 17 publications

(6 citation statements)

References 89 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, we did not observe significant changes in vacancy ordering with increasing pressure. Our results also suggest that there is no Fe 3+ at the T site of slightly hydrous wadsleyite, but up to 4% of the Fe cations may be at the T site of very hydrous wadsleyite, consistent with previous findings (Smyth et al 2014).…”

Section: Structure Refinementssupporting

confidence: 92%

Hydrous wadsleyite crystal structure up to 32 GPa

Wang,

Thompson,

Zhang

et al. 2023

American Mineralogist

View full text Add to dashboard Cite

Hydroxylation of wadsleyite, β-(Mg,Fe) 2 SiO 4 , is associated with divalent cation defects and well known to affect its physical properties. However, an atomic-scale understanding of the defect structure and hydrogen bonding at high pressures is needed to interpret the influence of water on the behavior of wadsleyite in the mantle transition zone. We have determined the pressure evolution of the wadsleyite crystal symmetry and structure, including all O…O interatomic distances, up to 32 GPa using singlecrystal X-ray diffraction on two well-characterized, Fe-bearing (Fo 90 ) samples containing 0.25(4) and 2.0(2) wt% H 2 O. Both compositions undergo a pressure-dependent monoclinic distortion from orthorhombic symmetry above 9 GPa, with the less hydrous sample showing a larger increase in distortion at increased pressures due to the difference in compressibility of the split M3 site in the monoclinic setting arising from preferred vacancy ordering at the M3B site. Although hydrogen positions cannot be modeled from the X-ray diffraction data, the pressure evolution of the longer O1…O4 distance This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America.The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

show abstract

Section: Structure Refinementssupporting

confidence: 92%

Hydrous wadsleyite crystal structure up to 32 GPa

Wang,

Thompson,

Zhang

et al. 2023

American Mineralogist

View full text Add to dashboard Cite

show abstract

“…Accordingly, it is necessary to consider the effect of non-hydrostatic growth environments on the oxygen species, which were found to be bonding with a minor fraction of the hydrogen. Additionally, hydrogen may also couple with Fe 3+ to exchange for Si 4+ at T sites 28 29 30 . Further neutron diffraction study is required to observe this cation-coupled substitution mechanism in iron-bearing hydrous wadsleyite crystals at elevated oxygen-fugacity conditions.…”

Section: Resultsmentioning

confidence: 99%

Quantitative analysis of hydrogen sites and occupancy in deep mantle hydrous wadsleyite using single crystal neutron diffraction

Purevjav

Okuchi

Tomioka

et al. 2016

Sci Rep

View full text Add to dashboard Cite

Evidence from seismological and mineralogical studies increasingly indicates that water from the oceans has been transported to the deep earth to form water-bearing dense mantle minerals. Wadsleyite [(Mg, Fe2+)2SiO4] has been identified as one of the most important host minerals incorporating this type of water, which is capable of storing the entire mass of the oceans as a hidden reservoir. To understand the effects of such water on the physical properties and chemical evolution of Earth’s interior, it is essential to determine where in the crystal structure the hydration occurs and which chemical bonds are altered and weakened after hydration. Here, we conduct a neutron time-of-flight single-crystal Laue diffraction study on hydrous wadsleyite. Single crystals were grown under pressure to a size suitable for the experiment and with physical qualities representative of wet, deep mantle conditions. The results of this neutron single crystal diffraction study unambiguously demonstrate the method of hydrogen incorporation into the wadsleyite, which is qualitatively different from that of its denser polymorph, ringwoodite, in the wet mantle. The difference is a vital clue towards understanding why these dense mantle minerals show distinctly different softening behaviours after hydration.

show abstract

“…Mrosko et al (2013) assigned the 3,700 cm −1 band to H in the tetrahedron, in agreement with Blanchard et al (2009), based on the fact that this band shifts to lower wavenumbers when iron content increases. This would imply that the tetrahedron shrinks upon iron incorporation, which is not the case (see Hazen et al, 1990;Smyth et al, 2014), or that the O-H. . .…”

Section: Infrared Spectra and Bands Assignmentmentioning

confidence: 99%

Examination of Water Quantification and Incorporation in Transition Zone Minerals: Wadsleyite, Ringwoodite and Phase D Using ERDA (Elastic Recoil Detection Analysis)

et al. 2018

View full text Add to dashboard Cite

Hydrous wadsleyite, ringwoodite, and phase D have been synthesized in the MgO-SiO 2-H 2 O and MgO-FeO-SiO 2-H 2 O systems at mantle transition zone conditions (15-21 GPa and 1,100-1,700 • C) to investigate their water incorporation using Elastic Recoil Detection Analysis (ERDA), which is an absolute quantitative method. Wadsleyite and ringwoodite water contents vary from 0.1 to 3.2 wt% H 2 O and for ringwoodite containing up to 1.16 wt% H 2 O we observe that the (Mg+Fe)/Si ratio vs. water content follows the same trend as for wadsleyite, indicating that H is substituting for Mg as for wadsleyite. We also measured, for the first time, the water content of phase D and observed that it varies from 6.7 to 11.2 wt% H 2 O, up to twice less than estimated from electron microprobe analysis totals. Using these experiments, we were able to determine the absorptivity coefficient for OH infrared absorption bands in four wadsleyite and five ringwoodite samples. The average for the two iron-free wadsleyite samples leads to an absorptivity of 69,000 ± 7,000 L/moles H 2 O/cm 2 , in very good agreement with previous determinations. The wadsleyite with 8 mole% Fe displays an absorptivity of 67,000 ± 5,000 L/moles H 2 O/cm 2. The absorptivity values vary from 118,500 ± 5,000 for Fefree ringwoodite to ±135,000 ± 9,000 for Fe-bearing ringwoodite (10% mole Fe). Our results show that absorptivity coefficient for OH infrared absorption of ringwoodite do not drastically change with Fe content and that the frequency-based calibration of Paterson (1982) underestimates its water determinations by 50%. This is very important to know when comparing data from different studies where different extinction coefficients have been used.

show abstract

Tetrahedral ferric iron in oxidized hydrous wadsleyite

Cited by 17 publications

References 89 publications

Hydrous wadsleyite crystal structure up to 32 GPa

Hydrous wadsleyite crystal structure up to 32 GPa

Quantitative analysis of hydrogen sites and occupancy in deep mantle hydrous wadsleyite using single crystal neutron diffraction

Examination of Water Quantification and Incorporation in Transition Zone Minerals: Wadsleyite, Ringwoodite and Phase D Using ERDA (Elastic Recoil Detection Analysis)

Contact Info

Product

Resources

About