Thermal conductivity of the deep Earth’s minerals

Thermal conductivity of the deep Earth’s minerals

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Datum:2010
1. Verfasser: Goncharov, A.
Format: Artikel
Sprache:English
Veröffentlicht: Інститут геофізики ім. С.I. Субботіна НАН України 2010
Schriftenreihe:Геофизический журнал
Online Zugang:http://dspace.nbuv.gov.ua/handle/123456789/101322
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Zitieren:Thermal conductivity of the deep Earth’s minerals / A. Goncharov // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 50-51. — Бібліогр.: 6 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
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spelling irk-123456789-1013222016-06-03T03:01:59Z Thermal conductivity of the deep Earth’s minerals Goncharov, A. 2010 Article Thermal conductivity of the deep Earth’s minerals / A. Goncharov // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 50-51. — Бібліогр.: 6 назв. — англ. 0203-3100 http://dspace.nbuv.gov.ua/handle/123456789/101322 en Геофизический журнал Інститут геофізики ім. С.I. Субботіна НАН України
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
language English
format Article
author Goncharov, A.
spellingShingle Goncharov, A.
Thermal conductivity of the deep Earth’s minerals
Геофизический журнал
author_facet Goncharov, A.
author_sort Goncharov, A.
title Thermal conductivity of the deep Earth’s minerals
title_short Thermal conductivity of the deep Earth’s minerals
title_full Thermal conductivity of the deep Earth’s minerals
title_fullStr Thermal conductivity of the deep Earth’s minerals
title_full_unstemmed Thermal conductivity of the deep Earth’s minerals
title_sort thermal conductivity of the deep earth’s minerals
publisher Інститут геофізики ім. С.I. Субботіна НАН України
publishDate 2010
url http://dspace.nbuv.gov.ua/handle/123456789/101322
citation_txt Thermal conductivity of the deep Earth’s minerals / A. Goncharov // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 50-51. — Бібліогр.: 6 назв. — англ.
series Геофизический журнал
work_keys_str_mv AT goncharova thermalconductivityofthedeepearthsminerals
first_indexed 2025-07-07T10:44:30Z
last_indexed 2025-07-07T10:44:30Z
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fulltext 0� ��������� ��� ���������������������� /#�)-(% '1%.�+,#(� #(%2 Thermal conductivity of the deep Earth’s minerals A. Goncharov, 2010 Geophysical Laboratory, Carnegie Institution of Washington, Washington, USA goncharov@gl.ciw.edu Knowledge of thermal conductivity of the deep Earth’s materials is critical for understanding of the Earth’s thermal structure, evolution, and dynamics. Here we report on direct measurements of the lat- tice and radiative thermal conductivity of mantle and core materials under the pressure-temperature (P- T) conditions approaching those in the Earth’s man- tle and core by using optical spectroscopy and pulsed laser techniques in diamond anvil cells (DAC). We developed and tested a new flash-heating high-pressure technique to measure thermal diffu- sivity, which involves time-resolved radiometry com- bined with a pulsed IR laser source [Beck et al., 2007]. The results for MgO, NaCl, and KCl obtained to 32 GPa and 2600 K agree with previous studies at low pressure and high temperature and enable tests of models for the combined pressure-tempe- rature dependence of thermal conductivity. Prelimi- nary results on the thermal conductivity of magne- sium silicate perovskite to 125 GPa and 4000 K and [Goncharov et al., 2010] suggest a larger value than what was previously estimated, although the uncertainty is very large. Future accurate experi- mental measurements of the phonon contribution to the thermal conductivity of lower mantle materi- als will require a number of carefully crafted experi- ments under high pressure and temperature condi- tions to determine the thermal conductivity of all the materials used in the DAC. Measurements of the thermal conductivity of Ar are currently in progress and they will be presented at the meeting. To determine the thermal conductivity of Fe and its temperature dependence at high pressures we use combined continuous and pulsed laser heating techniques. A thin plate of Fe is positioned in a medium (e.g., Ar), laser heating is applied from one side and the temperature is measured from both sides of the sample radiometrically. The thermal conductivity is determined by fitting the results of finite element calculations to the experimental re- sults. This work is currently in progress. Another technique of measurements of the ther- mal conductivity, time-domain thermoreflectance (TDTR), has been recently applied for the DAC stu- dies [Hsieh et al., 2009]. A collaborative study of the thermal conductivity of MgO single crystal (as a benchmark sample) at high pressures with a group of Prof. D. Cahill (University of Illinois) is currently in progress, and the preliminary results will be re- ported at the meeting. We will also present optical absorption data for lower mantle minerals to assess the effect of com- position (including iron oxidation state), structure, temperture, and iron spin state on radiative heat transfer. The ultimate goal is to determine through these measurements the radiative thermal conduc- ��������� ��� ���������������������� 0� ��� ��!"#�$%&'�("�%()�#*+#�' #(&"�&��&,#��-�%()� �)#..'(/ tivity of the Earth’s lower mantle. Optical absorp- tion spectra have been measured at pressures up to 133 GPa for major mantle minerals, including fer- ropericlase (Mg, Fe)O, silicate perovskite (Mg0.9Fe0.1)SiO3, and postperovskite Mg(1 x)FexSiO3 (x=0,1 0,3). We find that optical absorption spectra of lower mantle minerals depend on composition (including iron oxidation state), structure, and iron spin state. We find that the presence of ferric iron in perovskite and ferropericlase strongly affects the optical properties, while the effect of the spin pa- iring transition may be more secondary [Goncharov et al., 2006; 2008; 2009; 2010]. We also show that post-perovskite exhibits larger than perovskite opti- cal absorption in the near infrared and visible spec- tral ranges which may have a profound effect on the dynamics the lowermost mantle. Absorption spec- tra of ferropericlase up to 800 K and 60 GPa show minimal temperature dependence. The estimated pressure-dependent radiative con- ductivity, krad, from these data is 2—5 times lower than previously inferred from model extrapolations [Goncharov et al., 2009], with implications for the evolution of the mantle such as generation and sta- bility of thermo-chemical plumes in the lower man- tle. Further work is required for an accurate assess- ment of the radiative component of the thermal con- ductivity of lower mantle minerals, including the study of compositional and structural properties, as well as the iron spin state. These include (but are not limited to) study of mantle minerals with com- positions more realistic for the Earth’s interior (e.g., containing Al). I would like to acknowledge the following individu- als for their contributions to this project: V. V. Struzhkin, D. A. Dalton, M. Wong, J. Ojwang, P. Beck, S. Jacob- sen, S.-M. Thomas, J. Montoya, S. Kharlamova, B. Haugen, A. Savello, B. Militzer, R. Hemley, H. K. Mao, R. Kundargi, P. Lazor, Z. Konopkova, J. Sie- bert, J. Badro, D. Antonangeli, F. J. Ryerson, W. Mao, W.-P. Hsieh, D. G. Cahill. I acknowledge support from NSF EAR 0711358 and 0738873, Carnegie Institution of Washington, DOE/BES, DOE/ NNSA (CDAC), and the W. M. Keck Foundation. I wish to thank C. Arac- ne for her help in the thinning and cutting of the ferro- periclase samples. References Beck P., Goncharov A. F., Struzhkin V. V., Militzer B., Mao H. K., Hemley R. J. Measurement of thermal diffusivity at high pressure using a transient hea- ting technique // Appl. Phys. Lett.�— ����.���91. — P. 181914. Goncharov A. F., Struzhkin V. V., Jacobsen S. D. Reduced radiative conductivity of low-spin (Mg,Fe)O in the lower mantle // Science. — 2006. — 312. — P. 1205—1208. Goncharov A. F., Haugen B. D., Struzhkin V. V., Beck P., Jacobsen S. D. Radiative conductivity and Oxidation State of Iron in the Earth's Lower Mantle // Nature. — 2008. — 456. — P. 231—234. Goncharov A. F., Beck P., Struzhkin V. V., Hau- gen B. D., Jacobsen S. D. Thermal conductivity of lower mantle minerals // Phys. Earth Planet. Int. — 2009. — 174. — P. 24—32. Goncharov A. F., Struzhkin V. V., Montoya J., Khar- lamova S., Kundargi R., Siebert J., Badro J., An- tonangeli D., Ryerson F. J., Mao W. Effect of Composition, Structure, and Spin State on the Ther- mal Conductivity of the Earth’s Lower Mantle // Phys. Earth Planet. Int. — 2010. — 180. — P. 148—153. Hsieh W.-P., Chen B., Li J., Keblinski P., Cahill D. G. Pressure-tuning of the thermal conductivity of a laye- red crystal, muscovite // Phys. Rev. — 2009. — 80. — P. 180302(R).

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