As a pilot study of the role of water in the attenuation of seismic waves in the Earth’s upper mantle, we have performed a series of seismic-frequency torsional forced-oscillation experiments on a natural (Anita Bay) dunite containing accessory hydrous phases, at high temperatures to 13008C and confining pressure (Pc) of 200MPa, within a gas-medium high-pressure apparatus. Both oven-dried and pre-fired specimens wrapped in Ni^Fe foil within the (poorly) vented assembly were recovered essentially dry after 50^100 h of annealing at 13008C followed by slow staged cooling. The results for those specimens indicate broadly similar absorption-band viscoelastic behaviour, but with systematic differences in the frequency dependence of strain-energy dissipation Q1, attributed to differences in the small volume fraction of silicate melt and its spa-tial distribution. In contrast, it has been demonstrated that a new assembly involving a welded Pt capsule retains aqueous fluid
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Aizawa et al. (2007) studied this question.
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