Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles Calculations

Thompson, E. C.; Campbell, A. J.; Tsuchiya, Jun

doi:10.1029/2021gc009703

Cited by 4 publications

(3 citation statements)

References 56 publications

(142 reference statements)

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“…These compositions could serve as possible contributors to ULVZs. ULVZs have multiple proposed explanations, including FeSi formed through core‐mantle reactions (Mergner et al., 2021), hydrous phases such as (Al,Fe)OOH (Thompson et al., 2021), Fe‐rich post perovskite (Garnero & McNamara, 2008), Fe‐rich (Mg,Fe)O (Solomatova et al., 2016; Wicks et al., 2010), and patches of partial melt (Williams & Garnero, 1996). Partial melt is a likely explanation for ULVZs due to the 3:1 ratio of S‐to‐P wave velocity reduction (Garnero & McNamara, 2008; Williams & Garnero, 1996).…”

Section: Discussionmentioning

confidence: 99%

Carbon Storage in Earth's Deep Interior Implied by Carbonate‐Silicate‐Iron Melt Miscibility

Davis,

Solomatova,

Caracas

et al. 2023

Geochem Geophys Geosyst

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Carbonate melts have been proposed to exist in the lower mantle, but their interaction with other lower mantle melt compositions is poorly understood. To understand miscibility in the carbonate‐silicate‐metal melt system, we simulate endmember, binary, and ternary melt mixtures and study how their Gibbs free energies of mixing evolve with pressure. We find that carbonate‐metal and carbonate‐silicate melts have miscibility gaps that close with increasing pressure, while silicate‐metal melts are immiscible at all lower‐mantle pressures. Extending this analysis to the core‐mantle boundary, we suggest three miscible melt fields near the endmember carbonate, silicate, and iron melt compositions. Analysis of the densities of these miscible melt compositions indicates that some carbonate‐rich and some silicate‐rich melt compositions are gravitationally stable at the core‐mantle boundary and could be candidate compositions to explain ultra‐low velocity zones. Additionally, we evaluate the speciation of an example immiscible melt composition at various pressures throughout the mantle and identify reduced carbon species that would be expected to form in the melt. Our analysis reveals that a majority of Earth's carbon could have been transported to the core during core‐mantle differentiation and that much of Earth's carbon may be stored in the deep interior today.

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Section: Discussionmentioning

confidence: 99%

Carbon Storage in Earth's Deep Interior Implied by Carbonate‐Silicate‐Iron Melt Miscibility

Davis,

Solomatova,

Caracas

et al. 2023

Geochem Geophys Geosyst

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show abstract

“…ULVZs have multiple proposed explanations, including FeSi formed through core-mantle reactions (Mergner et al, 2021), hydrous phases such as (Al,Fe)OOH (Thompson et al, 2021), Fe-rich post perovskite (Garnero & McNamara, 2008), Fe-rich (Mg,Fe)O (Solomatova et al, 2016;Wicks et al, 2010), and patches of partial melt (Williams & Garnero, 1996). Partial melt is a likely explanation for ULVZs due to the 3:1 ratio of S-to-P wave velocity reduction (Garnero & McNamara, 2008;Williams & Garnero, 1996).…”

Section: Gibbs Free Energy Of Mixingmentioning

confidence: 99%

Carbon storage in Earth's deep interior implied by carbonate-silicate-iron melt miscibility

Davis

Solomatova

Caracas

et al. 2023

Preprint

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Carbonate melts have been proposed to exist in the lower mantle, but their interaction with other lower mantle melt compositions is poorly understood. To understand miscibility in the carbonate-silicate-metal melt system, we simulate endmember, binary, and ternary melt mixtures and study how their Gibbs free energies of mixing evolve with pressure. We find that carbonate-metal and carbonate-silicate melts have miscibility gaps that close with increasing pressure, while silicate-metal melts are immiscible at all lower-mantle pressures. Extending this analysis to the core-mantle boundary, we suggest three miscible melt fields near the endmember carbonate, silicate, and iron melt compositions. Analysis of the densities of these miscible melt compositions indicates that some carbonate-rich and some silicate-rich melt compositions are gravitationally stable at the core-mantle boundary and could be candidate compositions to explain ultra-low velocity zones. Additionally, we evaluate the speciation of an example immiscible melt composition at various pressures throughout the mantle and identify reduced carbon species that would be expected to form in the melt. Our analysis reveals that a majority of Earth’s carbon could have been transported to the core during core-mantle differentiation and that much of Earth’s carbon may be stored in the deep interior today.

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“…However, the formation of pyritetype AlOOH remains unverified, highlighting the need for further high-pressure, high-temperature experiments. Recent high-pressure experiments propose that δ-AlOOH, which is structurally similar to phase H, could remain stable in the lower mantle (Thompson et al, 2021). It has also been shown that Al can separate from bridgmanite and CaSiO 3 perovskite to form δ-AlOOH in the presence of H 2 O.…”

Section: Introductionmentioning

confidence: 99%

Electron density changes accompanying high-pressure phase transition in AlOOH

Gajda,

Parafiniuk,

Fertey

et al. 2024

MinMag

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An attempt to compare and describe the differences in the electron density distribution between two phase structures of AlOOH has been made. High-resolution, high-pressure experiments with α-AlOOH diaspore were conducted using single-crystal synchrotron X-ray diffraction data. A multipole model of experimental electron density in the α-AlOOH single crystal was refined. Simultaneously, similar multipole refinement was conducted for another phase of diaspore (δ-AlOOH), this time based on a previously published data set. Both results were compared and supported by density functional theory (DFT) calculations. Although the results are affected by the limited quality of the data, it is clear that the phase transition caused significant changes in the shape and arrangement of the atomic basins. Atomic basins are a much better tool to present subtle electron density distribution changes than traditional polyhedra. Straightforward comparison of datasets available in older scientific papers and current datasets is challenging because of differences in data quality and collection parameters. However, augmenting experimental data with computational results can help reveal important information in even incomplete datasets.

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Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles Calculations

Cited by 4 publications

References 56 publications

Carbon Storage in Earth's Deep Interior Implied by Carbonate‐Silicate‐Iron Melt Miscibility

Carbon Storage in Earth's Deep Interior Implied by Carbonate‐Silicate‐Iron Melt Miscibility

Carbon storage in Earth's deep interior implied by carbonate-silicate-iron melt miscibility

Electron density changes accompanying high-pressure phase transition in AlOOH

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