Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Sharp 660-km discontinuity controlled by extremely narrow binary post-spinel transition


The Earth’s mantle is characterized by a sharp seismic discontinuity at a depth of 660 km that can provide insights into deep mantle processes. The discontinuity occurs over only 2 km—or a pressure difference of 0.1 GPa—and is thought to result from the post-spinel transition, that is, the decomposition of the mineral ringwoodite to bridgmanite plus ferropericlase. Existing high-pressure, high-temperature experiments have lacked the pressure control required to test whether such sharpness is the result of isochemical phase relations or chemically distinct upper and lower mantle domains. Here, we obtain the isothermal pressure interval of the Mg–Fe binary post-spinel transition by applying advanced multi-anvil techniques with in situ X-ray diffraction with the help of Mg–Fe partition experiments. It is demonstrated that the interval at mantle compositions and temperatures is only 0.01 GPa, corresponding to 250 m. This interval is indistinguishable from zero at seismic frequencies. These results can explain the discontinuity sharpness and provide new support for whole-mantle convection in a chemically homogeneous mantle. The present work suggests that distribution of adiabatic vertical flows between the upper and lower mantles can be mapped on the basis of discontinuity sharpness.

This is a preview of subscription content, access via your institution

Access options

Buy this article

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Phase relations in the system Mg2SiO4–Fe2SiO4.
Fig. 2: Backscattered electron images of the samples recovered from 23.86 GPa and 1,700 K (M2268).
Fig. 3: Expansion of discontinuity thickness of the post-spinel transition boundary by the Verhoogen effect26.

Similar content being viewed by others

Data availability

Details of the cell assembly used, representative X-ray diffraction patterns, a backscattered electron image of Mg2SiO4 recovered sample, parameters for the thermodynamic calculations and supplementary discussion of thermodynamic calculations regarding the effects of secondary components can be found in the Supplementary Information. Any additional data can be requested by e-mailing the corresponding author.


  1. Xu, F., Vidale, J. E. & Earle, P. S. Survey of precursors to Pʹ Pʹ: fine structure of mantle discontinuities. J. Geophys. Res. Solid Earth 108, B12024 (2003).

    Google Scholar 

  2. Ito, E. & Takahashi, E. Postspinel transformations in the system Mg2SiO4–Fe2SiO4 and some geophysical implications. J. Geophys. Res. Solid Earth 94, 10637–10646 (1989).

    Article  Google Scholar 

  3. Jackson, I. & Rigden, S. M. in The Earth’s Mantle: Composition, Structure and Evolution (ed. Jackson, I.) 405–460 (Cambridge Univ. Press, 1998).

  4. Irifune, T. et al. Iron partitioning and density changes of pyrolite in Earth’s lower mantle. Science 327, 193–195 (2010).

    Article  Google Scholar 

  5. Hofmann, A. W. Mantle geochemistry: the message from oceanic volcanism. Nature 385, 219–229 (1997).

    Article  Google Scholar 

  6. Schubert, G., Turcotte, D. L. & Olson, P. Mantle Convection in the Earth and Planets (Cambridge Univ. Press, 2001).

  7. Anderson, D. L. Theory of the Earth (Blackwell Scientific, 1989).

  8. Murakami, M., Ohishi, Y., Hirao, N. & Hirose, K. A perovskitic lower mantle inferred from high-pressure, high-temperature sound velocity data. Nature 485, 90–94 (2012).

    Article  Google Scholar 

  9. Nishiyama, N., Irifune, T., Inoue, T., Ando, J. I. & Funakoshi, K. I. Precise determination of phase relations in pyrolite across the 660 km seismic discontinuity by in situ X-ray diffraction and quench experiments. Phys. Earth Planet. 143, 185–199 (2004).

    Article  Google Scholar 

  10. Katsura, T. et al. Post-spinel transition in Mg2SiO4 determined by high P-T in situ X-ray diffractometry. Phys. Earth Planet. 136, 11–24 (2003).

    Article  Google Scholar 

  11. Akaogi, M., Kojitani, H., Matsuzaka, K., Suzuki, T. & Ito, E. in Properties of Earth and Planetary Materials at High Pressure and Temperature Vol. 101 (eds Manghnani, M. H. & Yagi, T.) 373–384 (Am. Geophys. Union, 1998).

  12. Ishii, T. et al. Complete agreement of the post-spinel transition with the 660 km seismic discontinuity. Sci. Rep. 8, 6358 (2018).

    Article  Google Scholar 

  13. Katsura, T. et al. Olivine-wadsleyite transition in the system (Mg,Fe)2SiO4. J. Geophys. Res. Solid Earth 109, B02209 (2004).

    Article  Google Scholar 

  14. Fei, Y., Wang, Y. & Finger, L. W. Maximum solubility of FeO in (Mg, Fe)SiO3–perovskite as a function of temperature at 26 GPa: Implication for FeO content in the lower mantle. J. Geophys. Res. Solid Earth 101, 11525–11530 (1996).

    Article  Google Scholar 

  15. Nakajima, Y., Frost, D. J. & Rubie, D. C. Ferrous iron partitioning between magnesium silicate perovskite and ferropericlase and the composition of perovskite in the Earth’s lower mantle. J. Geophys. Res. Solid Earth 117, B08201 (2012).

    Google Scholar 

  16. Frost, D. J., Langenhorst, F. & Van Aken, P. A. Fe–Mg partitioning between ringwoodite and magnesiowüstite and the effect of pressure, temperature and oxygen fugacity. Phys. Chem. Miner. 28, 455–470 (2001).

    Article  Google Scholar 

  17. Frost, D. J. Fe2+–Mg partitioning between garnet, magnesiowüstite, and (Mg,Fe)2SiO4 phases of the transition zone. Am. Mineral. 88, 387–397 (2003).

    Article  Google Scholar 

  18. Holzapfel, C., Rubie, D. C., Mackwell, S. & Frost, D. J. Effect of pressure on Fe–Mg interdiffusion in (FexMg1− x)O, ferropericlase. Phys. Earth Planet. 139, 21–34 (2003).

    Article  Google Scholar 

  19. Holzapfel, C., Rubie, D. C., Frost, D. J. & Langenhorst, F. Fe–Mg interdiffusion in (Mg, Fe)SiO3 perovskite and lower mantle reequilibration. Science 309, 1707–1710 (2005).

    Article  Google Scholar 

  20. Stixrude, L. & Lithgow-Bertelloni, C. Thermodynamics of mantle minerals-II. Phase equilibria. Geophys. J. Int. 184, 1180–1213 (2011).

    Article  Google Scholar 

  21. Wood, B. J. Postspinel transformations and the width of the 670 km discontinuity: a comment on “postspinel transformations in the system Mg2SiO4–Fe2SiO4 and some geophysical implications” by E. Ito and E. Takahashi. J. Geophys. Res. Solid Earth 95, 12681–12685 (1990).

    Article  Google Scholar 

  22. Katsura, T., Yoneda, A., Yamazaki, D., Yoshino, T. & Ito, E. Adiabatic temperature profile in the mantle. Phys. Earth Planet. 183, 212–218 (2010).

    Article  Google Scholar 

  23. Fei, Y. et al. Experimentally determined postspinel transformation boundary in Mg2SiO4 using MgO as an internal pressure standard and its geophysical implications. J. Geophys. Res. Solid Earth 109, B02305 (2004).

    Article  Google Scholar 

  24. Tange, Y., Nishihara, Y. & Tsuchiya, T. Unified analyses for P-V-T equation of state of MgO: a solution for pressure-scale problems in high P–T experiments. J. Geophys. Res. Solid Earth 114, B03208 (2009).

    Google Scholar 

  25. Stixrude, L. Structure and sharpness of phase transitions and mantle discontinuities. J. Geophys. Res. Solid Earth 102, 14835–14852 (1997).

    Article  Google Scholar 

  26. Verhoogen, J. Phase changes and convection in the Earth’s mantle. Philos. Trans. R. Soc. Lond. A 258, 276–283 (1965).

    Article  Google Scholar 

  27. Christensen, U. R. Dynamic phase boundary topography by latent heat effects. Earth Planet. Sci. Lett. 154, 295–306 (1998).

    Article  Google Scholar 

  28. Richards, P. G. Weakly coupled potentials for high-frequency elastic waves in continuously stratified media. Bull. Seismol. Soc. Am. 64, 1575–1588 (1974).

    Google Scholar 

  29. Nakanishi, I. Reflections of P′ P′ from upper mantle discontinuities beneath the Mid-Atlantic Ridge. Geophys. J. 93, 335–346 (1988).

    Article  Google Scholar 

  30. Xu, Y., McCammon, C. & Poe, B. T. The effect of alumina on the electrical conductivity of silicate perovskite. Science 282, 922–924 (1998).

    Article  Google Scholar 

  31. Katsura, T. et al. A large-volume high-pressure and high-temperature apparatus for in situ X-ray observation, ‘SPEED-Mk. II’. Phys. Earth Planet. 143, 497–506 (2004).

    Article  Google Scholar 

  32. Ishii, T. et al. Generation of pressures over 40 GPa using Kawai-type multi-anvil press with tungsten carbide anvils. Rev. Sci. Instrum. 87, 024501 (2016).

    Article  Google Scholar 

  33. Ishii, T. et al. Pressure generation to 65 GPa in a Kawai-type multi-anvil apparatus with tungsten carbide anvils. High. Press. Res. 37, 507–515 (2017).

    Article  Google Scholar 

  34. Kuroda, K. et al. Determination of the phase boundary between ilmenite and perovskite in MgSiO3 by in situ X-ray diffraction and quench experiments. Phys. Chem. Miner. 27, 523–532 (2000).

    Article  Google Scholar 

  35. Ono, S. et al. In situ observation of ilmenite–perovskite phase transition in MgSiO3 using synchrotron radiation. Geophys. Res. Lett. 28, 835–838 (2001).

    Article  Google Scholar 

  36. Irifune, T. et al. The postspinel phase boundary in Mg2SiO4 determined by in situ X-ray diffraction. Science 279, 1698–1700 (1998).

    Article  Google Scholar 

  37. Shimojuku, A. et al. Growth of ringwoodite reaction rims from MgSiO3 perovskite and periclase at 22.5 GPa and 1,800 °C. Phys. Chem. Miner. 41, 555–567 (2014).

    Article  Google Scholar 

  38. Ishii, T., Kojitani, H. & Akaogi, M. Post-spinel transitions in pyrolite and Mg2SiO4 and akimotoite–perovskite transition in MgSiO3: precise comparison by high-pressure high-temperature experiments with multi-sample cell technique. Earth Planet. Sci. Lett. 309, 185–197 (2011).

    Article  Google Scholar 

  39. Ito, E. & Yamada, H. in High-Pressure Research in Geophysics Vol. 12 (eds. Akimoto, S. & Manghnani, M. H.) 405–419 (Center for Academic Publishing Japan, 1982).

  40. Schubert, G., Turcotte, D. L. & Olson, P. Mantle Convection in the Earth and Planets (Cambridge Univ. Press, 2001).

  41. Bina, C. R. A note on latent heat release from disequilibrium phase transformations and deep seismogenesis. Earth Planets Space 50, 1029–1034 (1998).

    Article  Google Scholar 

  42. Kojitani, H., Inoue, T. & Akaogi, M. Precise measurements of enthalpy of postspinel transition in Mg2SiO4 and application to the phase boundary calculation. J. Geophys. Res. Solid Earth 121, 729–742 (2016).

    Article  Google Scholar 

Download references


We appreciate H. Fischer, S. Übelhack, R. Njul, H. Schulze, U. Trenz and S. Linhardt at Bayerisches Geoinstitut for their technical assistance. We acknowledge N. Tomioka, A. Shatskiy, G. Manthilake, S.-M. Zhai, K. Saito, K. Kawabe, E. Ito, A. Kubo, S. Okita, T. Okishio, M. Sugita, M. Matsui, A. Kuwata, M.-S. Song and S. Yokoshi for their participation in the early stage of this study (2003–2004). This work was supported by the research project approved by DFG (KA 3434/7-1, KA3434/8-1, KA3434/9-1) and BMBF (05K16WC2) to T. Katsura and DFG (IS 350/1-1) to T.I. This project has been also supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (proposal no. 787 527). T.I. has been supported by a research fellowship for scientific research from the Japan Society for the Promotion of Science (JSPS) for Young Scientists, an overseas research fellowship from the Scientific Research of the JSPS for Young Scientists and an Alexander von Humboldt Postdoctoral Fellowship. The synchrotron X-ray diffraction experiments were performed in the beamline BL04B1 at SPring-8 with the approval of the Japan Synchrotron Radiation Research Institute (JASRI) (proposal no. 2003A0087, 2003B0638, 2004A0368, 2004B0497, 2015A1359, 2015B1196, 2016A1172, 2016A1274, 2016A1434, 2016B1094, 2017A1150, 2018A1071, 2018B1218).

Author information

Authors and Affiliations



T.I. conducted most of the experiments, analysed all the samples and data, conducted thermodynamic analysis in the Mg2SiO4–Fe2SiO4 system and wrote the manuscript. T.Katsura directed this project. R.H. and T.Katsura conducted trial runs of preliminary experiments. R.H. and H.F. helped in starting sample preparations. I.K. helped to establish the cell assembly. R.M. conducted thermodynamic calculations to discuss effects of secondary components. F.M., L.Y., Z.L., L.W., D.D., T.Y., S.B., R.F., T.Kawazoe, N.T., E.K., Y.H. and Y.T. operated synchrotron radiation experiments at the beamline BL04B1 at SPring-8. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Takayuki Ishii.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Primary handling editor(s): Melissa Plail; Rebecca Neely.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary information and figures

Supplementary Figs. 1–5.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Ishii, T., Huang, R., Myhill, R. et al. Sharp 660-km discontinuity controlled by extremely narrow binary post-spinel transition. Nat. Geosci. 12, 869–872 (2019).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing