Post-stishovite transition in hydrous aluminous SiO2

Koichiro Umemoto, Katsuyuki Kawamura, Kei Hirose, Renata M. Wentzcovitch

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Lakshtanov et al. (2007) showed that incorporation of aluminum and some water into SiO2 significantly reduces the post-stishovite transition pressure in SiO2. This discovery suggested that the ferroelastic post-stishovite transition in subducted MORB crust could be the source of reflectors/scatterers with low shear velocities observed in the mid to upper lower mantle. A few years later, a similar effect was observed in anhydrous Al-bearing silica. In this paper, we show by first principles static calculations and by molecular dynamics using inter-atomic potentials that hydrogen bonds and hydrogen mobility play a crucial role in lowering the post-stishovite transition pressure. A cooperative redistribution of hydrogen atoms is the main mechanism responsible for the transition pressure reduction in hydrous aluminous stishovite. The effect is enhanced by increasing hydrogen concentration. This perspective suggests a potential relationship between the depth of seismic scatterers and the water content in stishovite.

Original languageEnglish
Pages (from-to)18-26
Number of pages9
JournalPhysics of the Earth and Planetary Interiors
Volume255
DOIs
Publication statusPublished - Jun 1 2016

Fingerprint

stishovite
transition pressure
hydrogen
pressure reduction
lower mantle
scattering
mid-ocean ridge basalt
moisture content
reflectors
upper mantle
crusts
hydrogen atoms
Earth mantle
aluminum
silica
water content
crust
hydrogen bonds
molecular dynamics
silicon dioxide

Keywords

  • First principles
  • Hydrous aluminous SiO
  • Molecular dynamics
  • Post-stishovite transition

ASJC Scopus subject areas

  • Geophysics
  • Space and Planetary Science
  • Physics and Astronomy (miscellaneous)
  • Astronomy and Astrophysics

Cite this

Post-stishovite transition in hydrous aluminous SiO2 . / Umemoto, Koichiro; Kawamura, Katsuyuki; Hirose, Kei; Wentzcovitch, Renata M.

In: Physics of the Earth and Planetary Interiors, Vol. 255, 01.06.2016, p. 18-26.

Research output: Contribution to journalArticle

Umemoto, Koichiro ; Kawamura, Katsuyuki ; Hirose, Kei ; Wentzcovitch, Renata M. / Post-stishovite transition in hydrous aluminous SiO2 In: Physics of the Earth and Planetary Interiors. 2016 ; Vol. 255. pp. 18-26.
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