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

doi:10.1038/ncomms6428

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

^*Corresponding author for this work

Earth and Planetary Sciences

Research output: Contribution to journal › Article › peer-review

20 Scopus citations

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 language	English (US)
Article number	5428
Journal	Nature communications
Volume	5
DOIs	https://doi.org/10.1038/ncomms6428
State	Published - Nov 11 2014

Funding

We thank Maddury Somayazulu, Takashi Yoshino, Reinhard Boehler and Amol Kar-andikar for their experimental assistance. Suggestions from Takashi Nakagawa improved the manuscript. Jay Bass and Satoshi Okumura are gratefully acknowledged for their valuable comments. This work was supported by Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT)/The Japan Society for the Promotion of Science (JSPS) Kakenhi grant numbers 22684028, 24654170 and 25247087, and a Grant for Program Research from Frontier Research Institute for Interdisciplinary Sciences, Tohoku University (to M.M.), and by the National Science Foundation (NSF) EAR-1015239, NSF EAR/IF-1128867 and Army Research Office (to A.F.G.). Mössbauer experiments were performed under the approval of SPring-8 (2011A3501).

ASJC Scopus subject areas

General Chemistry
General Biochemistry, Genetics and Molecular Biology
General Physics and Astronomy

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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 M{\"o}ssbauer 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.",

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AU - Murakami, Motohiko

AU - Goncharov, Alexander F.

AU - Hirao, Naohisa

AU - Masuda, Ryo

AU - Mitsui, Takaya

AU - Thomas, Sylvia Monique

AU - Bina, Craig R.

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

Abstract

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ASJC Scopus subject areas

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