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On the rheology of the upper mantle
Author(s) -
Stocker R. L.,
Ashby M. F.
Publication year - 1973
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1029/rg011i002p00391
Subject(s) - rheology , olivine , mantle (geology) , exponent , thermodynamics , creep , geology , power law , dislocation creep , upper and lower bounds , grain size , diffusion creep , materials science , mineralogy , geophysics , grain boundary , physics , microstructure , mathematics , composite material , mathematical analysis , linguistics , philosophy , statistics
Mechanisms permitting the steady state deformation of crystalline solids are critically reviewed, and an approximate constitutive relationship is derived for fluid phase transport in a partial melt. (Fluid phase transport has a linear stress dependence and an inverse squared grain size dependence.) A set of rheologic material constants for olivine (Fo 85 ‐Fo 95 ) are derived from a combination of experimental data and empirical generalizations. Our preferred power law exponent n is 4.2, and the associated Dorn parameter is 1.2 × 10 4 . Dislocation creep below the high‐stress breakdown is the dominant deformation mechanism in the upper mantle. The possibility exists that the bottom of the upper mantle is not deforming at a significant rate (≥10 −14 /sec) if the activation volume for diffusion is greater than 40 cm³/mole.