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Bruce A. Buffett,1*Edward J. Garnero,2Raymond Jeanloz3
Unusual physical properties at the core-mantle boundary have been
inferred from seismic and geodetic observations in recentyears. We
show how both types of observations can be explainedby a layer of
silicate sediments, which accumulate at the topof the core as Earth
cools. Compaction of the sediments expelsmost of the liquid iron
but leaves behind a small amount of corematerial, which is entrained
in mantle convection and may accountfor the isotopic signatures of
core material in some hot spotplumes. Extraction of light elements
from the liquid core alsoenhances the vigor of convection in the core
and may increasethe power available to the geodynamo.
1 Department of Earth and Ocean Sciences,
University of British Columbia, Vancouver, British Columbia V6T 1Z4,
Canada.
2 Department of Geological Sciences, Arizona
State University, Tempe, AZ 85287, USA.
3 Department
of Earth and Planetary Science, University of California, Berkeley, CA
94720, USA.
*
To whom correspondence should be addressed. E-mail:
buffet{at}eos.ubc.ca
The editors suggest the following Related Resources on Science sites:
In Science Magazine
LETTERS
S. A. Morse;, Bruce Buffett, Edward Garnero, and Raymond Jeanloz (16 March 2001) Science291 (5511), 2090.
[DOI: 10.1126/science.291.5511.2090] |Full Text »
NEWS OF THE WEEK
Richard A. Kerr (17 November 2000) Science290 (5495), 1274b.
[DOI: 10.1126/science.290.5495.1274b] |Summary »|Full Text »
