Silicon and oxygen self-diffusion in stishovite

Implications for stability of SiO2-rich seismic reflectors in the mid-mantle

Fang Xu, Daisuke Yamazaki, Naoya Sakamoto, Wei Sun, Hongzhan Fei, Hisayoshi Yurimoto

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Diffusion of Si and O in single crystal stishovite was examined at pressures of 14.0–21.5 GPa and temperatures of 1673–2073 K. Self-diffusion coefficients of Si (DSi) and O (DO) were determined as DSi [m2/s]=2.4×10−12exp⁡{−(237[kJ/mol]+6.0[cm3/mol]×P)/RT} and DO [m2/s]=7.2×10−11exp⁡{−(263[kJ/mol]+4.8[cm3/mol]×P)/RT}, respectively, where P is pressure (in GPa), T is absolute temperature (in K) and R is the ideal gas constant. It was revealed that diffusion of Si is approximately one order of magnitude slower than that of O and, thus, Si is the rate-controlling element for plastic deformation of stishovite. Si diffusion in stishovite is assessed to be at least three orders of magnitude slower than that in bridgmanite under mid-mantle conditions. Therefore, it is anticipated that highly viscous SiO2-rich components subducted into the lower mantle persist as the seismic reflectors for long term without mixing up with the bridgmanite-dominated surrounding mantle.

Original languageEnglish
Pages (from-to)332-339
Number of pages8
JournalEarth and Planetary Science Letters
Volume459
DOIs
Publication statusPublished - Feb 1 2017

Fingerprint

stishovite
Silicon
silicon
reflectors
Earth mantle
Oxygen
mantle
oxygen
diffusion coefficient
ideal gas
plastic deformation
lower mantle
temperature
single crystals
Plastic deformation
Gases
Single crystals
crystal
Temperature
gas

Keywords

  • diffusion
  • seismic reflectors
  • stishovite
  • viscosity

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Silicon and oxygen self-diffusion in stishovite : Implications for stability of SiO2-rich seismic reflectors in the mid-mantle. / Xu, Fang; Yamazaki, Daisuke; Sakamoto, Naoya; Sun, Wei; Fei, Hongzhan; Yurimoto, Hisayoshi.

In: Earth and Planetary Science Letters, Vol. 459, 01.02.2017, p. 332-339.

Research output: Contribution to journalArticle

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