Viscosity of peridotite liquid up to 13 GPa: Implications for magma ocean viscosities

Christian Liebske, Bettina Schmickler, Hidenori Terasaki, Brent T. Poe, Akio Suzuki, Ken ichi Funakoshi, Ryota Ando, David C. Rubie

Research output: Contribution to journalArticlepeer-review

115 Citations (Scopus)

Abstract

The viscosity of synthetic peridotite liquid has been investigated at high pressures using in-situ falling sphere viscometry by combining a multi-anvil technique with synchrotron radiation. We used a newly designed capsule containing a small recessed reservoir outside of the hot spot of the heater, in which a viscosity marker sphere is embedded in a forsterite + enstatite mixture having a higher solidus temperature than the peridotite. This experimental setup prevents spheres from falling before a stable temperature above the liquidus is established and thus avoids difficulties in evaluating viscosities from velocities of spheres falling through a partially molten sample. Experiments have been performed between 2.8 and 13 GPa at temperatures ranging from 2043 to 2523 K. Measured viscosities range from 0.019 (± 0.004) to 0.13 (± 0.02) Pa s. At constant temperature, viscosity increases with increasing pressure up to ∼ 8.5 GPa but then decreases between ∼ 8.5 and 13 GPa. The change in the pressure dependence of viscosity is likely associated with structural changes of the liquid that occur upon compression. By combining our results with recently published 0.1 MPa peridotite liquid viscosities [D.B. Dingwell, C. Courtial, D. Giordano, A. Nichols, Viscosity of peridotite liquid, Earth Planet. Sci. Lett. 226 (2004) 127-138.], the experimental data can be described by a non-Arrhenian, empirical Vogel-Fulcher-Tamman equation, which has been modified by adding a term to account for the observed pressure dependence of viscosity. This equation reproduces measured viscosities to within 0.08 log10-units on average. We use this model to calculate viscosities of a peridotitic magma ocean along a liquid adiabat to a depth of ∼ 400 km and discuss possible effects on viscosity at greater pressures and temperatures than experimentally investigated.

Original languageEnglish
Pages (from-to)589-604
Number of pages16
JournalEarth and Planetary Science Letters
Volume240
Issue number3-4
DOIs
Publication statusPublished - Dec 15 2005
Externally publishedYes

Keywords

  • Differentiation
  • Magma ocean
  • Melting
  • Pressure
  • Silicate melt
  • Viscosity

ASJC Scopus subject areas

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

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