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Stability of magnesite and its high-pressure form in the lowermost mantle

Abstract

Carbonates are important constituents of marine sediments and play a fundamental role in the recycling of carbon into the Earth's deep interior via subduction of oceanic crust and sediments1,2,3. Study of the stability of carbonates under high pressure and temperature is thus important for modelling the carbon budget in the entire Earth system. Such studies, however, have rarely been performed under appropriate lower-mantle conditions and no experimental data exist at pressures greater than 80 GPa (refs 3–6). Here we report an in situ X-ray diffraction study of the stability of magnesite (MgCO3), which is the major component of subducted carbonates, at pressure and temperature conditions approaching those of the core–mantle boundary. We found that magnesite transforms to an unknown form at pressures above 115 GPa and temperatures of 2,100–2,200 K (depths of 2,600 km) without any dissociation, suggesting that magnesite and its high-pressure form may be the major hosts for carbon throughout most parts of the Earth's lower mantle.

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The authors declare that they have no competing financial interests.

References

  1. 1

    Chopin, C. Coesite and pure pyrope in high-grade blueschists of the western Alps: a first record and some consequences. Contrib. Mineral. Petrol. 86, 107–118 (1984)

  2. 2

    Becker, H. & Altherr, R. Evidence from ultra-high-pressure marbles for recycling of sediments into the mantle. Nature 358, 745–748 (1992)

  3. 3

    Biellmann, C., Gillet, P., Guyot, F., Peyronneau, J. & Reynard, B. Experimental evidence for carbonate stability in Earth's lower mantle. Earth Planet. Sci. Lett. 118, 31–41 (1993)

  4. 4

    Katsura, T. et al. Stability of magnesite under the lower mantle conditions. Proc. Jpn Acad. B 67, 57–60 (1991)

  5. 5

    Gillet, P. Stability of magnesite (MgCO3) at mantle pressure and temperature conditions: A Raman spectropic study. Am. Mineral. 78, 1328–1331 (1993)

  6. 6

    Fiquet, G. et al. Structural refinements of magnesite at very high pressure. Am. Mineral. 87, 1261–1265 (2002)

  7. 7

    Eggler, D. H., Kushiro, I. & Holloway, J. R. Stability of carbonate minerals in a hydrous mantle. Carnegie Inst. Wash. Yr Bk 75, 631–636 (1976)

  8. 8

    Wyllie, P. J. & Huang, W. L. Carbonation and melting reactions in the system CaO-MgO-SiO2-CO2 at mantle pressure with geophysical and petrological applications. Contrib. Mineral. Petrol. 54, 79–107 (1976)

  9. 9

    Wang, A., Pasteris, J. D., Meyer, H. O. A. & Dele-Duboi, M. L. Magnesite-bearing inclusion assemblage in natural diamond. Earth Planet. Sci. Lett. 141, 293–306 (1996)

  10. 10

    Domanik, K. J. & Holloway, J. R. Experimental synthesis and phase relations of phengitic muscovite from 6.5 to 11 GPa in a calcareous metapelite from the Dabie Mountains, China. Lithos 52, 51–77 (2000)

  11. 11

    Hammouda, T. High-pressure melting of carbonated eclogite and experimental constraints on carbon recycling and storage in the mantle. Earth Planet. Sci. Lett. 214, 357–368 (2003)

  12. 12

    Lin, C.-C. & Liu, L.-G. High pressure phase transformations in aragonite-type carbonates. Phys. Chem. Miner. 24, 149–157 (1997)

  13. 13

    Lin, C.-C. & Liu, L.-G. Post-aragonite phase transitions in strontianite and cerussite—a high-pressure Raman spectroscopic study. J. Phys. Chem. Solids 58, 977–987 (1997)

  14. 14

    Brown, J. M. & Shankland, T. J. Thermodynamic parameters in the earth as determined from seismic profiles. Geophys. J. R. Astron. Soc. 66, 579–596 (1981)

  15. 15

    Liu, L.-G. Genesis of diamonds in the lower mantle. Contrib. Mineral. Petrol. 134, 170–173 (1999)

  16. 16

    Harte, B. & Harris, J. W. Lower mantle mineral associations preserved in diamonds. Mineral. Mag. 58A, 384–385 (1994)

  17. 17

    Fukao, Y., Obayashi, M., Inoue, H. & Nenbai, M. Subducting slabs stagnant in the mantle transition zone. J. Geophys. Res. 97, 4809–4822 (1991)

  18. 18

    Van der Hilst, R. D., Engdahl, E. R., Spakman, W. & Nolet, G. Tomographic imaging of subducted lithosphere below northwest Pacific island arcs. Nature 353, 37–42 (1991)

  19. 19

    Ringwood, A. E. & Irifune, T. Nature of the 650-km seismic discontinuity: implications for mantle dynamics and differentiation. Nature 331, 131–136 (1988)

  20. 20

    Dziewonski, A. M. & Anderson, D. L. Preliminary reference earth model. Phys. Earth Planet. Inter. 25, 297–356 (1981)

  21. 21

    Anders, E. & Owen, T. Mars and Earth: origin and abundance of volatiles. Science 198, 453–465 (1977)

  22. 22

    Scott, H. P., Williams, Q. & Knittle, E. Stability and equation of state of Fe3C to 73 GPa: Implications for carbon in the Earth's core. Geophys. Res. Lett. 28, 1875–1878 (2001)

  23. 23

    Zhao, D. Seismic structure and origin of hotspots and mantle plumes. Earth Planet. Sci. Lett. 192, 251–265 (2001)

  24. 24

    Watanuki, T., Shimomura, O., Yagi, T., Kondo, T. & Isshiki, M. Construction of laser-heated diamond anvil cell system for in situ x-ray diffraction study at SPring-8. Rev. Sci. Instrum. 72, 1289–1292 (2001)

  25. 25

    Jamieson, J. C., Fritz, J. N. & Manghnani, M. H. in High-Pressure Research in Geophysics (eds Akimoto, S. & Manghnani, M. H.) 27 (Center for Academic Publications Japan, Tokyo, 1982)

  26. 26

    Mao, H. K., Bell, P. M., Shaner, J. W. & Steinberg, D. J. Specific volume measurements of Cu, Mo, Pd, and Ag and calibration of the ruby R1 fluorescence pressure gauge from 0.06 to 1 Mbar. J. Appl. Phys. 49, 3276–3283 (1978)

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Acknowledgements

We thank A. Kurio, M. Murakami, Y. Kuwayama and N. Sata for discussions and technical assistance. We also thank T. Katsura for providing the magnesite starting material. M.I. thanks T. Yagi for advice on DAC techniques. The in situ X-ray observations were conducted at BL10XU, SPring-8.

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Competing interests

The authors declare that they have no competing financial interests.

Correspondence to Maiko Isshiki or Tetsuo Irifune.

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Further reading

Figure 1: X-ray diffraction profiles with increasing pressure at the maximum temperatures in selected runs (ad).
Figure 2: Possible phase relations of MgCO3 in the deep mantle.

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