Document Detail

A perovskitic lower mantle inferred from high-pressure, high-temperature sound velocity data.
MedLine Citation:
PMID:  22552097     Owner:  NLM     Status:  In-Process    
The determination of the chemical composition of Earth's lower mantle is a long-standing challenge in earth science. Accurate knowledge of sound velocities in the lower-mantle minerals under relevant high-pressure, high-temperature conditions is essential in constraining the mineralogy and chemical composition using seismological observations, but previous acoustic measurements were limited to a range of low pressures and temperatures. Here we determine the shear-wave velocities for silicate perovskite and ferropericlase under the pressure and temperature conditions of the deep lower mantle using Brillouin scattering spectroscopy. The mineralogical model that provides the best fit to a global seismic velocity profile indicates that perovskite constitutes more than 93 per cent by volume of the lower mantle, which is a much higher proportion than that predicted by the conventional peridotitic mantle model. It suggests that the lower mantle is enriched in silicon relative to the upper mantle, which is consistent with the chondritic Earth model. Such chemical stratification implies layered-mantle convection with limited mass transport between the upper and the lower mantle.
Motohiko Murakami; Yasuo Ohishi; Naohisa Hirao; Kei Hirose
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Publication Detail:
Type:  Journal Article     Date:  2012-05-02
Journal Detail:
Title:  Nature     Volume:  485     ISSN:  1476-4687     ISO Abbreviation:  Nature     Publication Date:  2012 May 
Date Detail:
Created Date:  2012-05-03     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0410462     Medline TA:  Nature     Country:  England    
Other Details:
Languages:  eng     Pagination:  90-4     Citation Subset:  IM    
Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Sendai, Miyagi 980-8578, Japan.
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Comment In:
Nature. 2012 May 3;485(7396):51-2   [PMID:  22552094 ]

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