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The effect of an equilibrated melt phase on the shear creep and attenuation behavior of polycrystalline olivine
Author(s) -
Gribb Tye T.,
Cooper Reid F.
Publication year - 2000
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl011443
Subject(s) - attenuation , creep , materials science , olivine , crystallite , shear (geology) , phase (matter) , mineralogy , composite material , shear modulus , viscosity , microstructure , geology , optics , metallurgy , chemistry , physics , organic chemistry
The impact of a chemically and texturally equilibrated melt phase on the shear creep and attenuation behaviors of polycrystalline olivine has been measured experimentally at seismic‐to‐subseismic frequencies. The experiments were performed on aggregates that had a particularly uniform and fine grain size (∼3 µm). The effect of the melt phase (∼5 vol%) is to decrease the (Newtonian) viscosity by a factor of ∼6; there is no dramatic disaggregation effect or melt‐induced plummeting of the shear modulus. Both the melt‐free and melt‐bearing aggregates display an attenuation “band” of the form Q G −1 ∝ f −1 4 . This response cannot be attributed to a variation in microstructure; it is intrinsic to the diffusional creep behavior. There is no unique effect of the melt phase on the attenuation response: the slight increase in absorption of partial melt specimens is explained fully by the effect of the texturally equilibrated melt on aggregate viscosity.