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Compositional zoning in sodic amphiboles from the blueschist facies

Published online by Cambridge University Press:  05 July 2018

Robert Muir Wood
Robert Muir Wood*
Affiliation:
Department of Mineralogy and Petrology, Downing Place, Cambridge
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Summary

The sodic amphiboles possess two independent chemical substitution series (Fe3+-Al and Fe2+-Mg) that combine to provide a ‘plane’ of compositions. Yet at no single T and P are compositions covering the whole plane stable: (i) pure riebeckite exists under low-P conditions but breaks down in normal blueschists to give deerite; (ii) ferro-glaucophane is in competition at all except the lowest blueschist temperatures with almandine garnet; (iii) magnesio-riebeckite is stable at high-T and low-P but within the blueschist facies is replaced by the alternative higher density aegirine-talc assemblage; and (iv) glaucophane is stable only at high-P.

At higher T and P than those of the blueschists, competition from NaCa pyroxenes, garnets, and deerite first erodes, and then removes, nearly all sodic amphibole compositions. At low-P the normal sodic amphibole-forming reactions from stilpnomelane and chlorite (in the presence of iron oxides, albite, etc.) produce an initial ‘rie-beckitic’ amphibole that subsequently becomes more glaucophanitic with increasing P. Under certain conditions, perhaps connected with hydrous fluid overpressures, these reactions become transposed such that crossitic compositions become replaced whilst ferroglaucophane to glancophane compositions remain stable.

Type
Research Article
Information
Mineralogical Magazine , Volume 43 , Issue 330 , June 1980 , pp. 741 - 752
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1980

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References

Bancroft, (G. M.) and Burns, (R. G.), 1969. Mineral. Soc. Am. Special Paper. 2, 137.Google Scholar
Black, (P. M.), 1973. Contrib. Mineral. Petrol. 39, 55.CrossRefGoogle Scholar
Bocquet, (J.), 1971. Eclog. Geol. Helv. 64, 71.Google Scholar
Brown, (E. H.), 1974. Bull. geol. Soc. Am. 85, 333.2.0.CO;2>CrossRefGoogle Scholar
Carman, (J. H.), 1974. Am. Geophys. Union Trans. 55, 481.Google Scholar
Carpenter, (M. A.), 1979. Am. Mineral. 64, 102.Google Scholar
Chesterman, (C. W.), 1966. Calif. Div. Mines and Geol. Bull. 190, 503.Google Scholar
Coleman, (R. G.) and Lee, (D. E.), 1963. J. Petrol. 4, 260.CrossRefGoogle Scholar
de Roever, (E. W. F.), Beunk, (F. F.), and Kieft, (C.), 1976. Contrib. Mineral. Petrol.. 58, 221.CrossRefGoogle Scholar
Ernst, (W. G.), 1960a. Geochim. Cosmochim. Acta, 19, 10.CrossRefGoogle Scholar
Ernst, (W. G.) 1960b. J. Geol. 70, 689.CrossRefGoogle Scholar
Ernst, (W. G.) 1963. Am. Mineral. 48, 241.Google Scholar
Ernst, (W. G.) 1965. Bull. geol. Soc. Am. 76, 879.CrossRefGoogle Scholar
Ernst, (W. G.) and Wai, (C. M.), 1970. Am. Mineral. 55, 1226.Google Scholar
Ernst, (W. G.) 1979. Mineral. Mag. 43, 269.CrossRefGoogle Scholar
Eskola, (P.), 1929. Geol. Fören. Stockholm Frith. 51, 157.CrossRefGoogle Scholar
Helgeson, (H. C.), Delany, (J. M.), Nesbitt, (H. W.), and Bird, (D. K.), 1978. Am. J. Sci. 278A, 1.Google Scholar
Hoffman, (C.), 1972. Contrib. Mineral. Petrol. 34, 135.CrossRefGoogle Scholar
Holland, (T. J. B.), 1979. J. Geol. 87, 1.CrossRefGoogle Scholar
LHsfi, (L. C.), 1968. J. Petrol. 9, 40.Google Scholar
Maresch, (W. V.), 1973. Earth and Planet. Sci. Lett. 20, 385.CrossRefGoogle Scholar
Maresch, (W. V.) 1977. Tectonophysics. 43, 109.CrossRefGoogle Scholar
Milton, (C.) and Eugster, (H. P.), 1959. In Researches in Geochemistry, (ed. Abelson, P. H.), p. 118. J. Wiley, New York.Google Scholar
Miyashiro, (A.), 1957. J. Fac. Sci. Univ. of Tokyo. 11, 11, 57.Google Scholar
Miyashiro, (A.) and Banno, (S.), 1958. Am. J. Sc. 256, 97.CrossRefGoogle Scholar
Muir Wood, (R.), 1977. Ph.D. Thesis, Cambridge.Google Scholar
Muir Wood, (R.) 1979a. Geol. Mag. 116, 21.CrossRefGoogle Scholar
Muir Wood, (R.) 1979b. Ibid., 191.Google Scholar
Muir Wood, (R.) 1979c. Mineral. Mag. 43, 251.CrossRefGoogle Scholar
Popp, (R. K.) and Gilbert, (M. C.), 197. Am. Mineral. 57, 1210.Google Scholar
Råheim, (A.) and Green, (D. H.), 1974. Contrib. Mineral. Petrol. 48, 179.CrossRefGoogle Scholar
Schliested, (M.), 1978. Ibid. 66, 105.Google Scholar