Acoustic velocites of (MgxFe1-x)2SiO4 ringwoodite

Laboratory measurement of the elastic wave velocities of major minerals relevant to planet’s mantle are crucial to constrain the composition, mineralogy and temperature of the otherwise inaccessible deep interior of Earth. Ringwoodite is the most abundant phase in the lower half of the Earth’s transition zone (TZ). However, almost all existing measurements of its elastic properties are restricted to pressure (P) and temperature (T) conditions significantly below those of the mantle geotherm, with many made outside ringwoodite’s stability field. We propose to experimentally measure the acoustic velocities of ringwoodite with compositions between (Mg0.9Fe0.1)2SiO4 and (Mg0.5Fe0.5)2SiO4 at relevant mantle PT conditions using ultrasonic interferometry in the multi-anvil press. When combined with synchrotron X-ray source, it’s possible to accurately determine the pressure, density and length of the sample, therefore allow precise sound wave velocities to be obtained.