Kyushu University Academic Staff Educational and Research Activities Database
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Tomoaki KUBO Last modified date:2019.06.23

Professor / Material Science of Solar Planets
Department of Earth and Planetary Sciences
Faculty of Sciences

Graduate School
Undergraduate School
Other Organization

Academic Degree
Doctor of Science
Country of degree conferring institution (Overseas)
Field of Specialization
Earth and Planetary Interiors, Mineral physics
Total Priod of education and research career in the foreign country
Outline Activities
My group studies dynamics of Earth and planetary interiors based on experimental mineral physics at high pressure. We have several high-pressure devices, including a Kawai-type multi-anvil press, a deformation-DIA apparatus and diamond cells. We also conduct high-pressure in-situ X-ray studies at synchrotron facilities of SPring-8 and Photon Factory. By using these techniques, we study "deep rock dynamics" such as transformation kinetics, rheology, and their interactions in high-pressure minerals and ices. Recent and current research topics include metastable transformations and deep earthquakes, weakening of the lower-mantle slabs, internal dynamics of icy bodies, and non-equilibrium reactions in shocked meteorites and diamond inclusions.
Research Interests
  • Coupling of transformation and deformation at high pressure
    keyword : transformation, deformation, shear instability, deep earthquake, mantle convection, high-pressure deformation experiment, in-situ X-ray observation, acoustic emission
  • transformation kinetics and mantle dynamics
    keyword : high-pressure transformation, transformation mechanisms, transformation kinetics, TEM, High P-T in-situ X-ray diffraction, subducting oceanic plates
  • Atomic diffusion and rheology in Earth's mantle deep interior
    keyword : mantle convection, mantle rheology, atomic diffusion, grain growth, deformation experiment
  • Rheology and high-pressure transformations of icy materials
    keyword : icy moon, ice, plastic deformation, grain growth, atomic diffusion, high pressure deformation experiment
  • Non-equilibrium phase transformation in shocked meteorites
    keyword : shocked meteorites, P-T-t conditions of shock events, non-equilibrium phase transformation
Academic Activities
1. Tomoaki KUBO, Takumi Kato, Yuji Higo, Kenichi Funakoshi, Curious kinetic behavior in silica polymorphs solves seifertite puzzle in shocked meteorite, Sci. Adv. 1, e1500075 (2015). DOI: 10.1126/sciadv.1500075, 388, 2015.05, The presence of seifertite, one of the high-pressure polymorphs of silica, in achondritic shocked meteorites has been problematic because this phase is thermodynamically stable at more than ~100 GPa, unrealistically high-pressure conditions for the shock events in the early solar system. We conducted in situ x-ray diffraction measurements at high pressure and temperatures, and found that it metastably appears down to ~11 GPa owing to the clear difference in kinetics between the metastable seifertite and stable stishovite formations. The temperature- insensitive but time-sensitive kinetics for the formation of seifertite uniquely constrains that the critical shock duration and size of the impactor on differentiated parental bodies are at least ~0.01 s and ~50 to 100 m, respec- tively, from the presence of seifertite..
2. N. Doi, T. Kato, T. Kubo, M. Noda, R. Shiraishi, A. Suzuki, E. Ohtani, T. Kikegawa, Creep behavior during the eutectoid transformation of albite: Implications for the slab deformation in the lower mantle, EARTH AND PLANETARY SCIENCE LETTERS, 10.1016/j.epsl.2013.09.009, 388, 92-97, 2014.02.
3. M. NIshi, Tomoaki KUBO, T. Ohfuji, Takumi Kato, Y. Nishihara, T. Irifune, Slow Si-Al interdiffusion in garnet and stagnation of subducting slabs, EARTH AND PLANETARY SCIENCE LETTERS, 10.1016/j.epsl.2012.11.022, 361, 44-49, 2013.01.
4. S. Kaneshima, T. Kubo, S. Yoshioka, Geophysical and mineralogical constraints on the post-spinel transformation for the Tonga slab, PHYSICS OF THE EARTH AND PLANETARY INTERIORS, 10.1016/j.pepi.2012.02.009, 196, 23-31, 2012.04.
5. M. Nishi, Tomoaki KUBO, Takumi Kato, A. Tominaga, K. Funakoshi, Y. Higo, Exsolution kinetics of majoritic garnet from clinopyroxene in subducting oceanic crust, PHYSICS OF THE EARTH AND PLANETARY INTERIORS, 10.1016/j.pepi.2011.07.002, 189, 1-2, 47-55, 2011.11.
6. M. Nishi, T. Kubo, T. Kato, A. Tominaga, A. Shimojuku, N. Doi, K. Funakoshi, Y. Higo, Survival of majoritic garnet in diamond by direct kimberlite ascent from deep mantle, Geophys. Res. Lett., 37, doi:10.1029/2010GL042706, 2010, 2010.05.
7. T. Kubo, T. Kondo, A. Shimojuku, T. Kuwabara, T. Kato, T. Kikegawa, N. Hirao, Y. Ohishi, Time-resolved two-dimensional X-ray diffraction measurements of kinetic properties in polycrystalline high-pressure ices, J. Phys. Conf. Ser., 215, 012022, 2010, 2010.03.
8. T. Kubo, M. Kimura, T. Kato, M. Nishi, A. Tominaga, T. Kikegawa, K. Funakoshi, Plagioclase breakdown as an indicator for shock conditions of meteorites, Nature geoscience, 3, 41-45, 2010, 2010.01.
9. T. Kubo, H. Nakata, T. Kato, Effects of insoluble particles on grain growth in polycrystalline ice: Implications for rheology of ice shells of icy satellites, J. Mineral. Petrol. Sci., 104, 301-306, 2009, 2009.10.
10. T. Kubo, S. Kaneshima, Y. Torii, S. Yoshioka, Seismological and experimental constraints on metastable phase transformations and rheology of the Mariana slab, Earth Planet. Sci. Lett., 287, 12-23, 2009, 2009.08.
11. Akira Shimojuku ,Tomoaki Kubo, Eiji Ohtani, Tomoki Nakamura, Ryuji Okazaki, Ralf Dohmen, Sumit Chakraborty, Si and O diffusion in (Mg,Fe)2SiO4 wadsleyite and ringwoodite and its implications for the rheology of the mantle transition zone, Earth Planet. Sci. Lett., 284, 103-112, 2009, 2009.05.
12. T. Kubo, E. Ohtani, T. Kato, T. Kondo, T. Hosoya, A. Sano, and T. Kikegawa, Kinetics of the post-garnet transformation: Implications for density and rheology of subducting slabs, Phys. Earth Planet. Inter., 170, 181-192, 2008, 2008.06.
13. Kubo, T., Durham, W. B., Stern, L. A., Kirby, S. H., Grain-size sensitive creep in ice II, Science, vol. 311, 1267-1269, 2006.01.
14. Hosoya, T., Kubo, T., Ohtani, E., Sano, A., Funakoshi, K., Water controls the fields of metastable olivine in cold subducting slabs, Geophys. Res. Lett., 10.1029/2005GL023398, 32, 17, vol. 32, doi:10.1029/2005GL023398, 2005.01.
15. Kubo, T., Ohtani, E., and Funakoshi, K., Nucleation and growth kinetics of the α-β transformation in Mg2SiO4 determined by in-situ synchrotron X-ray powder diffraction, American Mineralogist, 89, 285-293, 2004.01.
16. T. Kubo, E. Ohtani, T. Kondo, T. Kato, M. Toma, T. Hosoya, A. Sano, T. Kikegawa, and T. Nagase, Metastable garnet in oceanic crust at the top of the lower mantle, Nature, vol. 420, 803-806, 2002, 2002.01.
17. T. Kubo, E. Ohtani, T. Kato, S. Urakawa, A. Suzuki, Y. Kanbe, K. Funakoshi, W. Utsumi, T. Kikegawa and K. Fujino, Mechanisms and kinetics of the postspinel transformation in Mg2SiO4, Phys. Earth Planet. Inter., vol. 129, 153-171, 2002, 2002.01.
18. T. Kubo, E. Ohtani, T. Kato, S. Urakawa, A. Suzuki, Y. Kanbe, K. Funakoshi, W. Utsumi, and K. Fujino, Formation of metastable assemblages and mechanisms of the grain-size reduction in the postspinel transformation of Mg2SiO4, Geophysical Research Letters, vol. 27, 807-810, 2000, 2000.01.
19. T. Kubo, E. Ohtani, T. Kato, T. Shinmei, and K. Fujino, Effects of water on the α-β transformation kinetics in San Carlos olivine, Science, vol. 25, 695-698, 1998, 1998.01.
1. T. Kubo, H. Kojitani, S. Kaneshima, Y. Higo, Y. Tange, Kinetics of the two-stage post-spinel transformation under subduction zone conditions: Implications for mantle flow across the 660-km discontinuity, Japan Geoscience Union meeting 2018, 2018.05.
2. T. Kubo, N. Doi, M. Imamura, T. Kato, Y. Higo and Y. Tange, In-situ X-ray observations of creep behavior during the olivine-spinel transformation in fayalite, American Geophysical Union 2016 Fall Meeting, 2016.12.
3. 久保友明, 岩里拓弥, 肥後祐司, T. Kato, 上原 誠一郎, 金嶋 聰, Y. Tange, Simultaneous observations of reaction kinetics, creep behavior, and AE activities during syndeformational antigorite dehydration at high pressures, American Geophysical Union 2015 Fall Meeting, 2015.12.
4. 岩里拓弥, 久保友明, 肥後祐司, T. Kato, 金嶋 聰, 上原 誠一郎, Y. Tange, Flow behaviors and AE activities during syndeformational antigorite dehydration at high pressures, 日本地球惑星連合2015年度大会, 2015.05.
5. S. Wang, Tomoaki KUBO, J. Ning, Y. Higo, K. Funakoshi, In-situ XRD Study of the Olivine – Ringwoodite Phase Transformation Kinetics: Application for Effects of Water on Its Growth Kinetics, AGU Fall Meeting, 2012.12.
6. Tomoaki KUBO, Takumi Kato, Doi Naoko, Yuji Higo, Formation of metastable seifertite, Japan Geoscience Union Meeting 2012, 2012.05.
  • Masayuki NISHI, Tomoaki KUBO and Takumi KATO (2009) Metastable transformations of eclogite to garnetite in subducting oceanic crust. Journal of Mineralogical and Petrological Sciences, 104, 192-198.
Educational Activities
Introduction to Solid Earth sciences
Introduction to experimental studies in Earth and planetary sciences
Rock and mineral physics