Electrical conductivity of orthopyroxene: Implications for the water content of the asthenosphere

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概要

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• Electrical conductivity of minerals is sensitive to water content and hence can be used to infer the water content in the mantle. However, previous studies to infer the water content in the upper mantle were based on pure olivine model of the upper mantle. Influence of other minerals particularly that of orthopyroxene needs to be included to obtain a better estimate of water content in view of the high water solubility in this mineral. Here we report new results of electrical conductivity measurements on orthopyroxene, and apply these results to estimate the water content of the upper mantle of Earth. We found that the electrical conductivity of orthopyroxene is enhanced by the addition of water in a similar way as other minerals such as olivine and pyrope garnet. Using these new results, we calculate the electrical conductivity of pyrolite mantle as a function of water content and temperature incorporating the temperature and water fugacity-dependent hydrogen partitioning. Reported values of asthenosphere conductivity of 4×10−2−10−1 S/m corresponds to the water content of 0.01–0.04 wt%, a result in good agreement with the petrological model of the upper mantle.(Communicated by Ikuo KUSHIRO, M.J.A.)

• 日本学士院の論文

著者

• Karato Shun-ichiro

  Department Of Geology And Geophysics University Of Minnesota

• DAI Lidong

  Laboratory for Study of the Earth’s Interior and Geofluids, Institute of Geochemistry, Chinese Acade

関連論文

• Some remarks on the origin of seismic anisotropy in the D" layer
• Electrical conductivity of orthopyroxene: Implications for the water content of the asthenosphere

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