High-pressure radiative conductivity of dense silicate glasses with potential implications for dark magmas

Motohiko Murakami, Alexander F. Goncharov, Naohisa Hirao, Ryo Masuda, Takaya Mitsui, Sylvia Monique Thomas, Craig R. Bina

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Abstract

The possible presence of dense magmas at Earth's core-mantle boundary is expected to substantially affect the dynamics and thermal evolution of Earth's interior. However, the thermal transport properties of silicate melts under relevant high-pressure conditions are poorly understood. Here we report in situ high-pressure optical absorption and synchrotron Mössbauer spectroscopic measurements of iron-enriched dense silicate glasses, as laboratory analogues for dense magmas, up to pressures of 85 GPa. Our results reveal a significant increase in absorption coefficients, by almost one order of magnitude with increasing pressure to ∼50 GPa, most likely owing to gradual changes in electronic structure. This suggests that the radiative thermal conductivity of dense silicate melts may decrease with pressure and so may be significantly smaller than previously expected under core-mantle boundary conditions. Such dark magmas heterogeneously distributed in the lower mantle would result in significant lateral heterogeneity of heat flux through the core-mantle boundary.

Original languageEnglish
Article number5428
JournalNature communications
Volume5
DOIs
Publication statusPublished - 2014 Nov 11

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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    Murakami, M., Goncharov, A. F., Hirao, N., Masuda, R., Mitsui, T., Thomas, S. M., & Bina, C. R. (2014). High-pressure radiative conductivity of dense silicate glasses with potential implications for dark magmas. Nature communications, 5, [5428]. https://doi.org/10.1038/ncomms6428