The effect of phase transition on the compressional wave velocity for a trachybasalt at high temperature and high pressure

Compressional wave velocities in a trachybasalt, from Yichuan County, Henan Province, have been measured at 2.0 GPa and up to 1 350℃ in a YJ-3000 t cubic-anvil highpressure apparatus. The run products have been gained at the same pressure but different temperatures. The observation of the thin sections of the run products indicates that, corresponding to the variation of the compressional wave velocity in the trachybasalt, the phase transition has taken place. The relationship between the change of the compressional wave velocity and the hydrous mineral dehydration, solid-solid phase transformation and partial melting has been discussed. The experimental data presented here are of great importance to elucidating the geological process in the earth’s interior.