A Reconnaissance of Trace Elements in Anorthoclase Megacrysts

R. A. Mason, J. V. Smith, J. B. Dawson and S. B. Treves
Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois USA 60637
Department of Geology, University of Sheffield, Sheffield, S1 3JD
Department of Geology, University of Nebraska, Lincoln, Nebraska USA 68508

Abstract: Major, minor, and trace elements were measured with electron and ion microprobes for eighteen anorthoclase megacrysts from five locations. Comparisons with concentration ranges tabulated by Smith (1974) show excellent agreement except for consistently lower values of Mg and B. The discrepancy for Mg probably reflects Mg-rich impurities contaminating samples analysed by bulk methods. The cause of the discrepancy for B is unknown and deserves further study. Samples from Mt. Erebus, Antarctica, contain glass inclusions from which the following crystal/liquid partition coefficients ensue: Mg, 0.008; P, 0.04; Ti, 0.08; Fe, 0.04; Ba, 5.2; Sr, 8; Rb, 0.27.

Mineralogical Magazine; March 1982 v. 46; no. 338; p. 7-11; DOI: 10.1180/minmag.1982.046.338.02
© 1982, The Mineralogical Society
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