Abstract
DIFFUSION in silicates plays a key role in a number of processes in the Earth's mantle, including viscous flow1–4, electrical conductance5–8 and the homogenization of chemical heterogeneities. Although cation diffusion rates have been measured in olivine at high pressures9,10, no data exist on the chemical transport properties of the silicate phases thought to predominate in the transition zone of the mantle (from 400 to 700 km depth). Here we present measurements of cation diffusion in the α-olivine phase and high-pressure β- and γ-spinel phases of Mg2SiO4 at pressures up to 14 GPa. We find that diffusion rates in both high-pressure phases are about three orders of magnitude faster than that of olivine. When coupled with convective thinning, these faster diffusion rates suggest that the transition zone is more efficient at mixing chemical heterogeneities than the olivine-dominated upper mantle. Furthermore, we calculate that the minimum size of chemical heterogeneities in the transition zone should be of the order of metres.
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
Karato, S. & Wu, P. Science 269, 771–778 (1993).
Karato, S., Rubie, D. & Yan, H. J. geophys. Res. 98, 9761–9768 (1993).
Jaoul, O. J. geophys. Res. 95, 17631–17642 (1990).
Karato, S. & Ogawa, M. Phys. Earth planet. Inter. 28, 312–319 (1982).
Akimoto, S. & Fujisawa, H. J. geophys. Res. 70, 443–449 (1965).
Miyamoto, M. & Takeda, H. Nature 303, 602–603 (1983).
Schock, R., Duba, A. & Shankland, T. J. J. geophys. Res. 94, 5829–5839 (1989).
Omura, K. Phys. Earth planet. Inter. 65, 292–307 (1991).
Misener, D. in Geochemical Transport and Kinetics (eds Hofmann, A. W., Giletti, B., Yoder, H. & Yund, R.) 117–129 (Carnegie Instn, Washington DC, 1974).
Bertran-Alvarez, Y., Jaoul, O. & Liebermann, R. C. Phys. Earth planet. Inter. 70, 102–118 (1992).
Morioka, M. Geochim. cosmochim. Acta 45, 1573–1580 (1981).
Buening, D. & Buseck, P. J. geophys. Res. 78, 6852–6862 (1973).
Clark, A. & Long, J. in Thomas Graham Memorial Symposium on Diffusion Processes (eds Sherwood, J. N. et al.) 511–521 (Gordon & Breach, London, 1971).
Katsura, T. & Ito, E. J. geophys. Res. 94, 15663–15670 (1989).
Crank, J. The Mathematics of Diffusion 2nd edn (Oxford Univ. Press, London, 1975).
Wagner, C. Acta Metall. 17, 99–107 (1969).
Joesten, R. in Diffusion, Atomic Ordering, And Mass Transport: Selected Problems in Geo-chemistry (ed. Ganguly, J.) 345–395 (Springer, New York, 1991).
Kamb, B. Am. Miner. 53, 1439–1455 (1968).
Horiuchi, H., Akaogi, M. & Sawamoto, H. in High-Pressure Research in Geophysics (eds Akimoto, S. & Maghnani, M. H.) 391–403 (Center for Academic Publications, Tokyo, 1982).
Kellogg, L. & Turcotte, D. L. J. geophys. Res. 95, 421–432 (1990).
Hofmann, A. W. & Hart, S. R. Earth planet. Sci. Lett. 38, 44–62 (1978).
Hoffmann, N. R. A. & McKenzie, D. Geophys. J. R. astr. Soc. 82, 163–206 (1985).
Ricard, Y., Vigny, C. & Froidevaux, C. J. geophys. Res. 94, 13739–13754 (1989).
Spada, G., Sabadini, R., Yuen, D. A. & Ricard, Y. Geophys. J. Int. 109, 683–700 (1992).
Karato, S. Phys. Earth planet. Inter. 55, 234–240 (1989).
Fukao, Y., Obayashi, M., Inoue, H. & Nenbai, M. J. geophys. Res. 97, 4809–4822 (1992).
van der Hilst, R., Engdahl, R., Spakman, W. & Nolet, G. Nature 353, 37–43 (1991).
Rubie, D., Karato, S., Yan, H. & O'Neill, H. St. Phys. Chem. Miner. 20, 315–322 (1993).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Farber, D., Williams, Q. & Ryerson, F. Diffusion in Mg2SiO4 polymorphs and chemical heterogeneity in the mantle transition zone. Nature 371, 693–695 (1994). https://doi.org/10.1038/371693a0
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/371693a0
This article is cited by
-
Theoretical study of lithium diffusion and fractionation in forsterite and its high-pressure phases
Physics and Chemistry of Minerals (2019)
-
Anisotropy of self-diffusion in forsterite grain boundaries derived from molecular dynamics simulations
Contributions to Mineralogy and Petrology (2016)
-
Fast cleaning in the deep
Nature (1994)
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.