The theoretical mineral physics group of Ehime University led by Dr. Taku Tsuchiya has developed high-precision computational techniques for studying Earth and planetary materials based on quantum mechanical theory and reported several outcomes for Earth’s lower mantle minerals and high-pressure hydrous phases. Their insights and discoveries clarify the mineralogy of Earth’s lower mantle and new mineral phases stabilized at the deep mantle.

Recent progress in theoretical mineral physics based on the ab initio quantum mechanical computation method has been dramatic in conjunction with the rapid advancement of computer technologies. It is now possible to predict stability, elasticity, and transport properties of complex minerals quantitatively with uncertainties that are comparable or even smaller than those attached in experimental data. These calculations under in situ high-pressure (P) and high-temperature (T) conditions are of particular interest, since they allow us to construct a priori mineralogical models of the deep Earth. In the present article, we briefly review our recent accomplishments in studying high-P phase relations, elasticity, thermal conductivity and rheological properties of major lower mantle silicate and oxide minerals including (Mg,Fe)SiO₃ bridgmanite, its high-pressure form post-perovskite, CaSiO₃ perovskite, (Mg,Fe)O ferroplericlase, and some hydrous phases (AlOOH, MgSiO₄H₂, FeOOH). Our analyses indicate that the pyrolitic composition can be used to describe the Earth’s properties quite well in terms all of densities, and P and S wave velocity. Computations also suggest some new hydrous compounds which could persist down to the deepest mantle and that the post-perovskite phase boundary is the boundary not only of the mineralogy but also of the thermal conductivity.

Reference URL: https://www.annualreviews.org/doi/10.1146/annurev-earth-071719-055139

Bibliographic Information

Ab initio study on the lower mantle minerals. Taku Tsuchiya, Jun Tsuchiya, Haruhiko Dekura, and Sebastian Ritterbex, Annual Review of Earth and Planetary Sciences, 48, published online on December 3, 2019. Doi:10.1146/annurev-earth-071719-055139

Fundings

• MEXT KAKENHI JP15H05826
• MEXT KAKENHI JP15H05834

Media

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  Lower mantle minerals

  Crystal structures of major mineral phases composing the Earth’s deep mantle, (Mg,Fe)SiO₃ bridgmanite (Brg), its high-pressure phase post-perovskite (PPv), CaSiO₃ perovskite, and (Mg,Fe)O ferropericlase

  credit : Ehime University
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