Sodium Silicates at the Boundary between the Transition Zone and the Lower Mantle: Compositional and Structural Patterns
| Autor: | Tetsuo Irifune, D. Yu. Pushcharovsky, Andrey V. Bobrov, A.P. Tamarova, Ekaterina A. Matrosova, Luca Bindi |
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| Rok vydání: | 2020 |
| Předmět: |
010504 meteorology & atmospheric sciences
Sodium Silicate perovskite Analytical chemistry chemistry.chemical_element engineering.material 010502 geochemistry & geophysics 01 natural sciences Mantle (geology) Ringwoodite chemistry Transition zone Earth and Planetary Sciences (miscellaneous) engineering Anhydrous General Earth and Planetary Sciences Paragenesis Periclase Geology 0105 earth and related environmental sciences |
| Zdroj: | Doklady Earth Sciences. 491:150-154 |
| ISSN: | 1531-8354 1028-334X |
| Popis: | The new results of experimental study of the Na2MgSiO4–Mg2SiO4 section of the SiO2–MgO–Na2O model system at 22–24 GPa and 1600–1900°C are discussed in this paper. An association of Na-bearing ringwoodite (up to 0.42 wt % Na2O) and the phase with the composition Na2MgSiO4 with a cristobalite-type structure was obtained at 22 GPa. Incorporation of Na in ringwoodite occurs through the mechanism Mg2+ → 2/3Na+ + 1/3Si4+ and results in an increase in the cell parameter in relation to that of pure Mg2SiO4 ringwoodite. A paragenesis of Na-bearing bridgmanite (up to 0.67 wt % Na2O), periclase, and anhydrous sodium phase X (Na2Mg2Si2O7) is formed at 23–24 GPa. Based on the data obtained, high-pressure Na–Mg silicates, Na2MgSiO4 and Na2Mg2Si2O7, may be considered as mineralogically probable mantle phases within the locally metasomatized mantle regions, although their finds as inclusions in diamond crystals are unlikely. |
| Databáze: | OpenAIRE |
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