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Science 14 June 1968:
Vol. 160. no. 3833, pp. 1218 - 1221
DOI: 10.1126/science.160.3833.1218
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Articles

Density Distribution in Earth

Frank Press 1

1 Department of Geology and Geophysics, Massachusetts Institute of Technology, Cambridge 02139

Earth models selected by a Monte Carlo procedure were tested against geophysical data; 5 million models were examined and six have passed all tests. Common features of successful models are an increased core radius and a chemically inhomogeneous core consistent with Fe-Ni alloy (20 to 50 percent Fe) for the solid portion and Fe-Si alloy (15 to 25 percent Fe) for the fluid core. The inhomogeneous mantle is consistent with an increase in the FeO:FeO + MgO ratio by a factor of 2 in the deep mantle. The transition zone is a region of not only phase change but also composition change; this condition would inhibit mantlewide convection. The upper-mantle solutions show large fluctuations in density; this state implies insufficient constraint on solutions for this region, or lateral variations in mantle composition ranging from pyrolite to eclogite.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Hotspots, Basalts, and the Evolution of the Mantle.
D. L. Anderson and D. L. Anderson (1981)
Science 213, 82-89
   Abstract »    PDF »
A Model for Plate Tectonic Evolution of Mantle Layers.
W. R. Dickinson, W. R. Dickinson, and W. C. Luth (1971)
Science 174, 400-404
   Abstract »    PDF »
The Upper Mantle of the Earth.
L. Knopoff and L. Knopoff (1969)
Science 163, 1277-1287
   PDF »


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Science. ISSN 0036-8075 (print), 1095-9203 (online)