Effect of composition, structure, and spin state on the thermal conductivity of the Earth's lower mantle

The change in electronic structure of iron at high pressures to spin-paired states in ferropericlase, silicate perovskite, and post-perovskite may have a profound influence on the thermal conductivity of the lower mantle. Here, we present optical absorption data for lower mantle minerals to assess t...

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Bibliographic Details
Published in:Physics of the earth and planetary interiors 2010-06, Vol.180 (3), p.148-153
Main Authors: Goncharov, A.F., Struzhkin, V.V., Montoya, J.A., Kharlamova, S., Kundargi, R., Siebert, J., Badro, J., Antonangeli, D., Ryerson, F.J., Mao, W.
Format: Article
Language:English
Subjects:
CHEMICAL COMPOSITION
Diamond anvil cell
EARTH MANTLE
Electronic spin transition
GEOSCIENCES
High pressure
Iron bearing Earth's minerals
IRON COMPOUNDS
Lower mantle
MORPHOLOGY
OPTICAL PROPERTIES
PEROVSKITE
SPIN
THERMAL CONDUCTIVITY
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Summary:The change in electronic structure of iron at high pressures to spin-paired states in ferropericlase, silicate perovskite, and post-perovskite may have a profound influence on the thermal conductivity of the lower mantle. Here, we present optical absorption data for lower mantle minerals to assess the effect of composition (including iron oxidation state), structure, and iron spin state on radiative heat transfer. We confirm that the presence of ferric iron in ferropericlase strongly affects the optical properties, while the effect of the spin-pairing transition may be more secondary. We also show that post-perovskite exhibits larger optical absorption in the near infrared and visible spectral ranges than perovskite which may have a profound effect on the dynamics the lowermost mantle. We present preliminary results from measurements of the phonon thermal conductivity of perovskite at 125 GPa using a pulsed laser heating technique. The available data suggest a larger value than what previously estimated, although the uncertainty is large.
ISSN:0031-9201
1872-7395
DOI:10.1016/j.pepi.2010.02.002