Abstract
It had long been accepted that the 400-km seismic discontinuity in the Earth's mantle results from the phase transition of (Mg,Fe)2-SiO4-olivine to its high-pressure polymorph β-spinel (wadsleyite), and that the 660-km discontinuity results from the breakdown of the higher-pressure polymorph γ-spinel (ringwoodite) to MgSiO3-perovskite and (Mg,Fe)O-magnesiowüstite1,2,3,4. An in situ multi-anvil-press X-ray study5 indicated, however, that the phase boundary of the latter transition occurs at pressures 2 GPa lower than had been found in earlier studies using multi-anvil recovery experiments6 and laser-heated diamond-anvil cells7. Such a lower-pressure phase boundary would be irreconcilable with the accuracy of seismic measurements of the 660-km discontinuity, and would thus require a mineral composition of the mantle that is significantly different from what is currently thought. Here, however, we present measurements made with a laser-heated diamond-anvil cell which indicate that γ-Mg2SiO4 is stable up to pressure and temperature conditions equivalent to 660-km depth in the Earth's mantle (24 GPa and 1,900 K) and then breaks down into MgSiO3-perovskite and MgO (periclase). We paid special attention to pressure accuracy and thermal pressure in our experiments, and to ensuring that our experiments were performed under nearly hydrostatic, inert pressure conditions using a variety of heating methods. We infer that these factors are responsible for the different results obtained in our experiments compared to the in situ multi-anvil-press study5.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Ringwood, A. E. Phase transformations and their bearing on the constitution and dynamics of the mantle. Geochim. Cosmochim. Acta 55, 2083–2110 (1991).
Poirier, J. P. in Introduction to the Physics of the Earth's Interior (eds Putnis, A. & Liebermann, R. C. ) 214–226 (Cambridge Univ. Press, Cambridge, 1991).
Zhao, Y. & Anderson, D. L. Mineral physics constraints on the chemical composition of the Earth's lower mantle. Phys. Earth Planet. Inter. 85, 273–292 (1994).
Navrotsky, A. Physics and Chemistry of Earth Materials (Cambridge Univ. Press, Cambridge, 1994).
Irifune, T. E. A. The postspinel phase boundary in Mg2SiO4 determined by in situ X-ray diffraction. Science 279, 1698–1700 (1998).
Ito, E. & Takahashi, E. Postspinel transformations in the system Mg2SiO4-Fe2SiO4 and some geophysical implications. J. Geophys. Res. 94, 10637–10646 (1989).
Boehler, R. & Chopelas, A. A new approach to laser heating in high pressure mineral physics. Geophys. Res. Lett. 18, 1147–1150 (1991).
Katsura, T. & Ito, E. The system Mg2SiO4-Fe2SiO4 at high pressures and temperatures: precise determination of stabilities of olivine, modified spinel, and spinel. J. Geophys. Res. 94, 15663–15670 (1989).
Liu, L. A new high pressure phase of spinel. Earth Planet. Sci. Lett. 41, 398–404 (1978).
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).
Chopelas, A. Estimates of mantle relevant Clapeyron slopes in the MgSiO3 system from high-pressure spectroscopic data. Am. Miner. 84, 233–244 (1999).
Manghnani, M. H. et al. in Physics of Solids under High Pressure (ed. Schilling, J. S.) 47–55 (North Holland, Amsterdam, 1981).
Heinz, D. L. & Jeanloz, R. The equation of state of the gold calibration standard. J. Appl. Phys. 55, 885–893 (1984).
Ming, L. C., Xiong, D. & Manghnani, M. H. Isothermal compression of Au and Al to 20 GPa. Physica B 139, 174–176 (1986).
Anderson, O. L., Isaak, D. G. & Yamamoto, S. Anharmonicity and the equation of state for gold. J. Appl. Phys. 65, 1534–1543 (1989).
Getting, I. C. & Kennedy, G. C. Effect of pressure on the emf of chromel-alumel and platinum-platinum 10% rhodium thermocouples. J. Appl. Phys. 41, 4552–4562 (1970).
Boehler, R. High-pressure experiments and the phase diagram of lower mantle and core materials. Rev. Geophys. 38, 221–245 (2000).
Chopelas, A. The fluorescence sideband method for obtaining acoustic velocities at high compressions: application to MgO and MgAl2O4. Phys. Chem. Miner. 23, 25–37 (1996).
Mao, H. K., Xu, J. & Bell, P. M. Calibration of the ruby pressure gauge to 800 kbar under quasi-hydrostatic conditions. J. Geophys. Res. 91, 4673–4676 (1986).
Zha, C. S., Mao, H. K. & Hemley, R. J. A primary pressure scale to 55 GPa from new measurements of equation of state and elasticity for MgO. AIRAPT Proc. 136, (1999).
Serghiou, G., Zerr, A., Chudinovskikh, L. & Boehler, R. The coesite-stishovite transition in a laser-heated diamond cell. Geophys. Res. Lett. 22, 441–444 (1995).
Shimomura, O., Yamaoka, S., Nakazawa, H. & Fukunaga, O. in High Pressure Research in Geophysics (eds Akimoto, >S. & Manghnani, M. H.) 49–60 (Center for Academic Publishing of Japan, Tokyo, 1982).
Ragan, D. D., Gustavsen, R. & Schiferl, D. Calibration of the ruby R1 and R2 fluorescence shifts as a function of temperature from 0 to 600 K. J. Appl. Phys. 72, 5539–5544 (1992).
Datchi, F., Le Toullec, R. & Loubeyre, P. Improved calibration of the SrB4O7:Sm2+ optical pressure gauge: advantages at very high pressures and high temperatures. J. Appl. Phys. 81, 3333–3339 (1997).
Yen, J. & Nicol, M. Temperature dependence of the ruby luminescence method for measuring high pressures. J. Appl. Phys. 72, 5535–5538 (1992).
Lacam, A. & Chateau, C. The SrB4O7:Sm2+ optical sensor for diamond anvil cells. J. Appl. Phys. 66, 366–370 (1989).
Boehler, R. & Zerr, A. Perovskite temperature profile. Science 265, 723 (1994).
Boehler, R. Melting and thermal expansion of iron in uniformly laser-heated diamond anvil cells. High Pressure Res. 5, 702–704 (1990).
Chopelas, A., Boehler, R. & Ko, T. Thermodynamics and behavior of γ-Mg2SiO4 at high pressure: implications for Mg2SiO4 phase equilibrium. Phys. Chem. Mineral. 21, 352–359 (1994).
Acknowledgements
We thank A. Zerr for assistance with the CO2-laser heating experiments.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Chudinovskikh, L., Boehler, R. High-pressure polymorphs of olivine and the 660-km seismic discontinuity. Nature 411, 574–577 (2001). https://doi.org/10.1038/35079060
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/35079060
This article is cited by
-
Density Patterns of the Upper Mantle Under Asia and the Arctic: Comparison of Thermodynamic Modelling and Geophysical Data
Pure and Applied Geophysics (2020)
-
The pressure-induced ringwoodite to Mg-perovskite and periclase post-spinel phase transition: a Bader’s topological analysis of the ab initio electron densities
Physics and Chemistry of Minerals (2012)
-
Ultrasonic measurements of single-crystal gold under hydrostatic pressures up to 8 GPa in a Kawai-type multi-anvil apparatus
Chinese Science Bulletin (2007)
-
Stability and P–V–T equation of state of KAlSi3O8-hollandite determined by in situ X-ray observations and implications for dynamics of subducted continental crust material
Physics and Chemistry of Minerals (2005)
-
Mantle cookbook calibration
Nature (2001)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.