Tt. Gribb et Rf. Cooper, The effect of an equilibrated melt phase on the shear creep and attenuation behavior of polycrystalline olivine, GEOPHYS R L, 27(15), 2000, pp. 2341-2344
The impact of a chemically and texturally equilibrated melt phase on the sh
ear creep and attenuation behaviors of polycrystalline olivine has been mea
sured experimentally at seismic-to-subseismic frequencies. The experiments
were performed on aggregates that had a particularly uniform and fine grain
size (similar to 3 mu m). The effect of the melt phase (similar to 5 vol%)
is to decrease the (Newtonian) viscosity by a factor of similar to 6; ther
e is no dramatic disaggregation effect of melt-induced plummeting of the sh
ear modulus. Both the melt-free and melt-bearing aggregates display an atte
nuation "band" of the form Q(G)(-1) proportional to f(-0.4). This response
cannot be attributed to a variation in microstructure; it is intrinsic to t
he diffusional creep behavior. There is no unique effect of the melt phase
on the attenuation response: the slight increase in absorption of partial m
elt specimens is explained fully by the effect of the texturally equilibrat
ed melt on aggregate viscosity.