Rheological Properties of the Lower Mantle

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The earth's lower mantle is mainly composed of (Mg, Fe)SiO3 perovskite and (Mg, Fe)O magnesiowüstite. It is essential to determine the rheological properties of MgSiO3 perovskite and periclase for understanding the rheology of the lower mantle. High pressure and temperature experiments were carried out under lower mantle conditions to determine their rheological properties. The grain growth rates of perovskite and periclase were determined to be G10.6 [ml=1 X 10-57.4t [sec] exp(-320.8 [kJ/mol] IRT) and G10.8 [m] = 1 X10-62.3t [sec] exp(-247.0 [kJ/mol]/RT), respectively, where G is grain size at time t, R is the gas constant and T is the absolute temperature. The lattice diffusion coefficient (D1) and grain boundary diffusion coefficient (Dsb) of silicon in MgSiO3 perovskite were determined at 25 GPa and 1673-2073 K to be D1 [m2/sec]=3.76 X 10-10exp(-338 [kJ/mol] /RT) and δDsb [m3/sec]=1.02 X 10-16 exp(-303 [kJ/mol] /RT), respectively, where δ is the width of the grain boundary. The grain size of perovskite in the lower mantle is estimated to be 1-10 mm, which suggests diffusion creep (Nabarro-Herring creep) as a dominant deformation mechanism in the greater part of the lower mantle. The present results indicate that the subducting slab is much softer than the surrounding lower mantle due to the slow grain growth rate.

Original languageEnglish
Pages (from-to)19-25
Number of pages7
JournalReview of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu
Volume9
Issue number1
DOIs
Publication statusPublished - 1999
Externally publishedYes

Fingerprint

Perovskite
Earth mantle
periclase
Grain growth
Creep
Grain boundaries
diffusion coefficient
grain boundaries
grain size
Silicon
Theophylline
Rheology
Crystal lattices
rheology
Gases
Earth (planet)
perovskite
slabs
Temperature
silicon

Keywords

  • grain growth
  • grain-size
  • lower mantle
  • MgSiO3 perovskite
  • rheology
  • silicon-diffusion
  • viscosity

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

Cite this

Rheological Properties of the Lower Mantle. / Yamazaki, Daisuke.

In: Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu, Vol. 9, No. 1, 1999, p. 19-25.

Research output: Contribution to journalArticle

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