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Science 20 January 1967:
Vol. 155. no. 3760, pp. 325 - 327
DOI: 10.1126/science.155.3760.325
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Articles

Fractionation of Potassium/Rubidium by Amphiboles: Implications Regarding Mantle Composition

Stanley R. Hart 1 and L. T. Aldrich 1

1 Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, D.C.

We show that the rubidium in amphiboles is generally depleted with respect to potassium. The K:Rb ratios of 50 analyzed amphiboles range from 100 to 5000, averaging 1120. This fractionation effect holds for potassium concentrations ranging from 0.05 to 1.5 percent. The K:Rb ratios of abyssal tholeiites do not place unambiguous limits on the K:Rb ratio of the upper mantle, since partial melting of a mantle material such as amphibole peridotite would produce a liquid with a K:Rb ratio higher than that in the initial material. Large-scale mineralogic control of distributions of trace elements in the mantle could produce trends with depth that are the reverse of trends normally attributed to differentiation processes.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Petrogenesis of Basaltic Volcanic Rocks from the Pribilof Islands, Alaska, by Melting of Metasomatically Enriched Depleted Lithosphere, Crystallization Differentiation, and Magma Mixing.
J. M. Chang, T. C. Feeley, and M. R. Deraps (2009)
J. Petrology
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Science. ISSN 0036-8075 (print), 1095-9203 (online)