NAL phase in K-rich portions of the lower mantle

Chie Kato, Kei Hirose, Tetsuya Komabayashi, Haruka Ozawa, Yasuo Ohishi

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

The stability of the K-rich new aluminous (NAL) phase was examined on the join Na1.00Mg2.00Al4.80Si1.15O 12-K1.00Mg2.00Al4.80Si 1.15O12 (Na100-K100) up to 144 GPa by X-ray diffraction in a laser-heated diamond anvil cell. Single-phase K100 and Na50K50 NAL were formed up to the lower mantle conditions, and the NAL phase coexisted with the calcium ferrite-type (CF) phase at 120 GPa and 2300 K for the Na75K25 bulk composition. This is a striking contrast to the K-free (Na100) NAL that becomes unstable above 27 GPa at 1850 K, which suggests that potassium stabilizes NAL at significantly higher pressures. K-rich NAL may host potassium in the lower mantle that contains K2O more than 0.09 wt %. In addition, the NAL phase likely formed owing to partial melting in the ultralow-velocity zone or because of a basal magma ocean. Future seismological observations may clarify whether NAL is a radiogenic heat source above the core-mantle boundary. Key Points Potassium expands the stability of the NAL phase dramatically K-rich NAL is stable o the lowermost mantle conditions NAL forms in the whole lower mantle where the K2O content is higher than 900 ppm

Original languageEnglish
Pages (from-to)5085-5088
Number of pages4
JournalGeophysical Research Letters
Volume40
Issue number19
DOIs
Publication statusPublished - Oct 16 2013
Externally publishedYes

Fingerprint

lower mantle
Earth mantle
potassium
diamond anvil cell
ferrite
core-mantle boundary
heat source
partial melting
anvils
heat sources
laser
calcium
X-ray diffraction
magma
mantle
ferrites
oceans
diamonds
melting
ocean

Keywords

  • Al phase
  • CF phase
  • high pressure
  • lower mantle
  • NAL phase
  • phase relation

ASJC Scopus subject areas

  • Earth and Planetary Sciences(all)
  • Geophysics

Cite this

Kato, C., Hirose, K., Komabayashi, T., Ozawa, H., & Ohishi, Y. (2013). NAL phase in K-rich portions of the lower mantle. Geophysical Research Letters, 40(19), 5085-5088. https://doi.org/10.1002/grl.50966

NAL phase in K-rich portions of the lower mantle. / Kato, Chie; Hirose, Kei; Komabayashi, Tetsuya; Ozawa, Haruka; Ohishi, Yasuo.

In: Geophysical Research Letters, Vol. 40, No. 19, 16.10.2013, p. 5085-5088.

Research output: Contribution to journalArticle

Kato, C, Hirose, K, Komabayashi, T, Ozawa, H & Ohishi, Y 2013, 'NAL phase in K-rich portions of the lower mantle', Geophysical Research Letters, vol. 40, no. 19, pp. 5085-5088. https://doi.org/10.1002/grl.50966
Kato C, Hirose K, Komabayashi T, Ozawa H, Ohishi Y. NAL phase in K-rich portions of the lower mantle. Geophysical Research Letters. 2013 Oct 16;40(19):5085-5088. https://doi.org/10.1002/grl.50966
Kato, Chie ; Hirose, Kei ; Komabayashi, Tetsuya ; Ozawa, Haruka ; Ohishi, Yasuo. / NAL phase in K-rich portions of the lower mantle. In: Geophysical Research Letters. 2013 ; Vol. 40, No. 19. pp. 5085-5088.
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