Elastic properties of anorthite at high temperature and high pressure

Abstract

To investigate elastic properties of subducted crustal minerals at P-T conditions of crust and upper most mantle, we performed in situ measurement of the elastic wave velocities of anorthite at temperatures up to 1100 ^oC at less than 2.0 GPa (in stability field) and up to 500 ^oC at 2.0-7.0 GPa. In this study, we found a drop of elastic wave velocities at ~240^oC in <2.5GPa, and gradual decrease of the velocities in >3GPa and <500^oC. These velocity changes are considered to be caused by the elastic softening by the phase transitions from P(-1)  to high-T(-1)  and to high-P(-1), respectively.