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Geophysical Monograph Series

 

Keywords

  • Subduction zones

Index Terms

  • 3902 Mineral Physics: Creep and deformation
  • 5102 Physical Properties of Rocks: Acoustic properties
  • 8162 Tectonophysics: Rheology—mantle
  • 8120 Tectonophysics: Dynamics of lithosphere and mantle—general

Article

GEOPHYSICAL MONOGRAPH SERIES, VOL. 138, PP. 83-105, 2003

Rheology of the upper mantle and the mantle wedge: A view from the experimentalists

G. Hirth and D. Kohlstedt

In this manuscript we review experimental constraints for the viscosity of the upper mantle. We first analyze experimental data to provide a critical review of flow law parameters for olivine aggregates and single crystals deformed in the diffusion creep and dislocation creep regimes under both wet and dry conditions. Using reasonable values for the physical state of the upper mantle, the viscosities predicted by extrapolation of the experimental flow laws compare well with independent estimates for the viscosity of the oceanic mantle, which is approximately 1019 Pa s at a depth of ∼100 km. The viscosity of the mantle wedge of subduction zones could be even lower if the flux of water through it can result in olivine water contents greater than those estimated for the oceanic asthenosphere and promote the onset of melting. Calculations of the partitioning of water between hydrous melt and mantle peridotite suggest that the water content of the residue of arc melting is similar to that estimated for the asthenosphere. Thus, transport of water from the slab into the mantle wedge can continually replenish the water content of the upper mantle and facilitate the existence of a low viscosity asthenosphere.

Citation: Hirth, G., and D. Kohlstedt (2003), Rheology of the upper mantle and the mantle wedge: A view from the experimentalists, in Inside the Subduction Factory, Geophys. Monogr. Ser., vol. 138, edited by J. Eiler, pp. 83–105, AGU, Washington, D. C., doi:10.1029/138GM06.

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