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Electrical conductivity measurements of brucite under crustal pressure and temperature conditions

Abstract

Hydrous minerals are crucial because their occurrence is associated with seismic activity through the dehydration process that occurs in the earth’s crust and/or mantle. We have developed a technique to observe the dehydration reaction of brucite using electrical conductivity variation under sealed conditions. The electrical conductivity of brucite was measured as a function of temperature. The confining pressure for the measurements was 1 GPa, which represents that of the lower crust. Two types of remarkable electrical conductivity variation were observed. During the first heating, the conductivity of the sample showed a linear variation below 700 K, as was expected from the Arrhenius equation. Once the temperature was increased to near the dehydration boundary, the sample showed a high conductivity. Even though only a small amount of H2O was formed after dehydration, bulk conductivity of the sample varied greatly, presumably caused by a combination of the presence of coexisting solid and fluid phases and a mixed electronic and ionic conduction mechanism operating in the sample.

References

  1. Freund, F., On the electrical conductivity structure of the stable continental crust, J. Geodyn., 35, 353–388, 2003.

  2. Fuji-ta, K., T. Katsura, and Y. Tainosho, Electrical conductivity measurement of granulite under mid- to lower crustal pressure-temperature conditions, Geophy. J. Int., 157, 79–86, 2004.

  3. Fukui, H., T. Inoue, T. Yasui, T. Katsura, K. Funakoshi, and O. Ohtaka, Decomposition of brucite up to 20 GPa: evidence for high MgO -solubility in the liquid phase, Eur. J. Miner., 17, 261–267, 2005.

  4. Johnson, M. C. and D. Walker, Brucite [Mg(OH)2] dehydration and the molar volume of H2O to 15 GPa, Am. Miner., 78, 271–284, 1993.

  5. Jones, A. G., Electrical Conductivity of the Continental Lower Crust, in Continental Lower Crust, edited by D. M. Fountain, R. J. Arculus, and R. W. Kay, Elsevier, Chapter 3, 81–143, 1992.

  6. Kanzaki, M., Dehydration of brucite (Mg(OH)2) at high pressures detected by differential thermal analysis, Geophys. Res. Lett., 18, 12,2189–2192, 1991.

  7. Meade, C. and R. Jeanloz, Deep-focus earthquakes and recycling of water into the Earth’s mantle, Science, 252, 68–72, 1991.

  8. Nesbitt, B., Electrical resistivities of crustal fluids, J. Geophys. Res., 98, B3, 4301–4310, 1993.

  9. Schramke, J. A., D. M. Kerrick, and J. G. Blencoe, Experimental determination of the brucite=periclase+water equilibrium with a new volumetric technique, Am. Miner., 67, 269–276, 1982.

  10. Shinoda, K. and N. Aikawa, Interlayer proton transfer in brucite under pressure by polarized IR spectroscopy to 5.3 GPa, Phys. Chem. Miner., 25, 197–202, 1998.

  11. Young, C. T. and M. R. Kitchen, A magnetotelluric transect in the Oregon coast range, J. Geophys. Res., 94, 14185–14193, 1989.

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Correspondence to Kiyoshi Fuji-ta.

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Fuji-ta, K., Katsura, T., Matsuzaki, T. et al. Electrical conductivity measurements of brucite under crustal pressure and temperature conditions. Earth Planet Sp 59, 645–648 (2007). https://doi.org/10.1186/BF03352725

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Key words

  • Brucite
  • electrical conductivity
  • X-ray diffraction