Geochemical modeling of mantle differentiation and crustal growth

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doi: 10.1029/JB084iB11p06091
Authors:O'Nions, R. K.; Evensen, N. M.; Hamilton, P. J.
Author Affiliations:Primary:
Lamont-Doherty Geol. Obs., Palisades, N.Y., United States
Volume Title:Journal of Geophysical Research
Source:Journal of Geophysical Research, 84(B11), p.6091-6101. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0148-0227
Publication Date:1979
Note:In English. Lamont-Doherty Geol. Obs.; Contrib. No. 2832. 88 refs.; illus. incl. tables
Summary:A simple two-reservoir. model with time-dependent transport coefficients between the reservoirs has been used to model the abundances of K, Ar, Rb, Sr, Sm, Nd, U, Th, and Pb and the isotopic compositions of Ar, Sr, Nd, and Pb in the earth's mantle and continental crust. The transport coefficients, like heat production, are considered to decay exponentially with time. Models which involve the whole mantle in generating the continental crust yield 87Sr/144 and 143Nd/144Nd ratios for the residual mantle which are higher and lower than midocean ridge basalts, respectively. A model which involves only half of the mantle in the production of continental crust produces a residual mantle with isotope ratios similar to those of midocean ridge basalt. The 40Ar/36Ar ratios in the atmosphere and suboceanic mantle are reproduced by this model without any inequality in the upward transport coefficients of K and Ar but with a smaller downward transport coefficient for Ar than for K. The results imply that the earth's crust may have developed by extraction of material from only half of the mantle and constrain the possible convective regimes that have existed in the mantle. [M.J. Le B.]
Subjects:Actinides; Alkali metals; Alkaline earth metals; Argon; Chemical composition; Composition; Continental crust; Convection; Crust; Differentiation; Earth; Geochemistry; Heterogeneity; Isotopes; Lead; Mantle; Mathematical models; Metals; Migration of elements; Models; Neodymium; Noble gases; Potassium; Rare earths; Rubidium; Samarium; Strontium; Theoretical studies; Thorium; Trace elements; Uranium; Evolution; Ratios
Abstract Numbers:82M/2879
Record ID:1980018269
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute.
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