Meeting room "Glova", 4 floor, Integrated Research Building
Abstract
Stishovite, the rutile-structure polymorph of SiO2, is stable at pressure from 7 GPa to 54 GPa. It is a potential component of petrological phase assemblages in the Earth's mantle. According to the phase relations of MORB, subducted oceanic crust contains ~20% stishovite in the lower mantle conditions. Therefore stishovite is one of the most important mineral for modeling and interpretating the structure of the Earth's interior, and its high-pressure and high-temperature elastic and thermodynamic properties are important for interpretations of seismic observations in the mid lower mantle. Because of the importance, many previous researches have been reported about thermoelasticity of stishovite. However, the experimental conditions were limited to about 23 GPa using Kawai-type multi-anvil apparatus and then it is very desirable to extrapolate this limitation to the mid lower mantle conditions. Recently, technical developments in the KMA allow us to achieve the Earth's mid lower mantle conditions by using sintered diamond anvils with great stabilities in the high-pressure and high-temperature generations. In this study, we conducted in-situ synchrotron X-ray diffraction experiments by using a KMA-type press known as "SPEED-Mk.II" at BL04B1 beamline in SPring-8 and measured the pressure-volume-temperature data of stishovite up to 55 GPa and 1900 K region, which corresponds to the pressure conditions of the mid lower mantle. Present EOS model enables us to calculate the density of stishovite up to mid lower mantle conditions precisely.
For inquiry：Taku Tsuchiya TEL:（089）927-8198
E-mail takut@sci.ehime-u.ac.jp
