Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles Calculations
Abstract The stability, structure, and elastic properties of pyrite‐type (FeS2 structured) FeO2H were determined using density functional theory‐based computations with an internally consistent Coulombic self‐interaction term (Ueff). The properties of pyrite‐type FeO2H are compared to that of pyrite...
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| Format: | Article |
| Language: | English |
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Wiley
2021-05-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2021GC009703 |
| _version_ | 1827771778734227456 |
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| author | Elizabeth C. Thompson Andrew J. Campbell Jun Tsuchiya |
| author_facet | Elizabeth C. Thompson Andrew J. Campbell Jun Tsuchiya |
| author_sort | Elizabeth C. Thompson |
| collection | DOAJ |
| description | Abstract The stability, structure, and elastic properties of pyrite‐type (FeS2 structured) FeO2H were determined using density functional theory‐based computations with an internally consistent Coulombic self‐interaction term (Ueff). The properties of pyrite‐type FeO2H are compared to that of pyrite‐type AlO2H, with which it likely forms a solid solution at high temperature, as well as the respective lower pressure CaCl2‐type polymorphs of both endmembers: ϵ‐FeOOH and δ‐AlOOH. Due to substantial differences in the CaCl2‐type → pyrite‐type structural transition pressures of these endmembers, the stabilities of the (Al,Fe)O2H solid solution polymorphs are anticipated to be compositionally driven at lower mantle pressures. As the geophysical properties of (Al,Fe)OOH are structurally dependant, interpretations regarding the contribution of pyrite‐type FeO2H to seismically observed features must take into account the importance of this broad phase loop. With this in mind, Fe‐rich pyrite‐type (Al,Fe)OOH may coexist with Al‐dominant CaCl2‐type δ‐(Al,Fe)OOH in the deep Earth. Furthermore, pyrite‐type (Al0.5–0.6,Fe0.4–0.5)O2H can reproduce the reduced compressional and shear velocities characteristic of seismically observed ultra low velocity zones in the Earth's lowermost mantle while Al‐dominant but Fe‐bearing CaCl2‐type δ‐(Al,Fe)OOH may contribute to large low shear velocity provinces. |
| first_indexed | 2024-03-11T12:59:03Z |
| format | Article |
| id | doaj.art-f597fe35dca24990a4f89e515045e0e0 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:59:03Z |
| publishDate | 2021-05-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-f597fe35dca24990a4f89e515045e0e02023-11-03T16:55:31ZengWileyGeochemistry, Geophysics, Geosystems1525-20272021-05-01225n/an/a10.1029/2021GC009703Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles CalculationsElizabeth C. Thompson0Andrew J. Campbell1Jun Tsuchiya2Department of Earth and Environmental Systems Sewanee: The University of the South Sewanee TN USADepartment of the Geophysical Sciences University of Chicago Chicago IL USAGeodynamics Research Center Ehime University Matsuyama JapanAbstract The stability, structure, and elastic properties of pyrite‐type (FeS2 structured) FeO2H were determined using density functional theory‐based computations with an internally consistent Coulombic self‐interaction term (Ueff). The properties of pyrite‐type FeO2H are compared to that of pyrite‐type AlO2H, with which it likely forms a solid solution at high temperature, as well as the respective lower pressure CaCl2‐type polymorphs of both endmembers: ϵ‐FeOOH and δ‐AlOOH. Due to substantial differences in the CaCl2‐type → pyrite‐type structural transition pressures of these endmembers, the stabilities of the (Al,Fe)O2H solid solution polymorphs are anticipated to be compositionally driven at lower mantle pressures. As the geophysical properties of (Al,Fe)OOH are structurally dependant, interpretations regarding the contribution of pyrite‐type FeO2H to seismically observed features must take into account the importance of this broad phase loop. With this in mind, Fe‐rich pyrite‐type (Al,Fe)OOH may coexist with Al‐dominant CaCl2‐type δ‐(Al,Fe)OOH in the deep Earth. Furthermore, pyrite‐type (Al0.5–0.6,Fe0.4–0.5)O2H can reproduce the reduced compressional and shear velocities characteristic of seismically observed ultra low velocity zones in the Earth's lowermost mantle while Al‐dominant but Fe‐bearing CaCl2‐type δ‐(Al,Fe)OOH may contribute to large low shear velocity provinces.https://doi.org/10.1029/2021GC009703AlOOHelasticityFeOOHLLSVPpyriteULVZ |
| spellingShingle | Elizabeth C. Thompson Andrew J. Campbell Jun Tsuchiya Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles Calculations Geochemistry, Geophysics, Geosystems AlOOH elasticity FeOOH LLSVP pyrite ULVZ |
| title | Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles Calculations |
| title_full | Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles Calculations |
| title_fullStr | Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles Calculations |
| title_full_unstemmed | Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles Calculations |
| title_short | Elastic Properties of the Pyrite‐Type FeOOH‐AlOOH System From First‐Principles Calculations |
| title_sort | elastic properties of the pyrite type feooh alooh system from first principles calculations |
| topic | AlOOH elasticity FeOOH LLSVP pyrite ULVZ |
| url | https://doi.org/10.1029/2021GC009703 |
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