Acoustic velocites of enstatite at mantle PT conditions

We are proposing to measure the acoustic velocity (vs and vp) of enstatite, the second most abundant mineral in ultramafic assemblages at depths extending to ~ 400 km beneath Earth’s surface. MgSiO3 enstatite and FeSiO3 ferrosilite are both known to undergo a series of pressure- and temperature-induced phase transitions that alter seismic velocity. However, we are unaware of any measurements of the seismic velocities of enstatite at mantle conditions, with current predictions relying on extrapolations of ambient temperature and ambient pressure data. We will perform experiments on ID06-LVP to simultaneously measure the crystallography, compressional and shear wave velocity of pure enstatite and Fe-bearing enstatite samples at conditions extending to ~ 10 GPa and 1600 K. This will contribute directly to the interpretation of seismic observations from studies of Earth’s upper mantle.