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Crepisson C., Blanchard M., Bureau H., Sanloup C., Withers A. C., Khodja H., Surble S., Raepsaet C., Beneut K., Leroy C., Giura P., Balan Etienne. (2014). Clumped fluoride-hydroxyl defects in forsterite : implications for the upper-mantle. Earth and Planetary Science Letters, 390, p. 287-295. ISSN 0012-821X.

Titre du document
Clumped fluoride-hydroxyl defects in forsterite : implications for the upper-mantle
Année de publication
2014
Type de document
Article référencé dans le Web of Science WOS:000333998400028
Auteurs
Crepisson C., Blanchard M., Bureau H., Sanloup C., Withers A. C., Khodja H., Surble S., Raepsaet C., Beneut K., Leroy C., Giura P., Balan Etienne
Source
Earth and Planetary Science Letters, 2014, 390, p. 287-295 ISSN 0012-821X
The mechanism and magnitude of fluorine incorporation in H-bearing forsterite were investigated through a combined experimental and theoretical approach. Forsterite samples were synthesized in a piston cylinder press at 2 and 4 GPa, in hydrous conditions, with or without fluorine. High fluorine solubilities of 1715 and 1308 ppm F were measured by particle induced gamma-ray emission (PIGE) in forsterite samples synthesized at 2 and 4 GPa, respectively. In addition, first-principles calculations based on density functional theory were performed in order to investigate the coupled incorporation mechanisms of fluorine and water in forsterite. Our results demonstrate the close association of fluoride, hydroxyl groups and Si vacancies. Comparison of experimental and theoretical infrared absorption spectra enables assignment of the nine OH stretching bands (3500-3700 cm(-1)) observed in F-rich synthetic forsterite to clumped fluoride-hydroxyl defects in the forsterite crystal structure. Noteworthily, similar bands were previously recorded on some natural olivine with Mg/(Mg+Fe) molar ratio down to 0.86. Fluorine and water cycles are therefore strongly coupled through the nominally anhydrous minerals and the mantle fluorine budget can be entirely accommodated by these mineral phases.
Plan de classement
Géologie et formations superficielles [064]
Localisation
Fonds IRD [F B010061931]
Identifiant IRD
fdi:010061931
Contact