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On polygenetic myrmekite

Published online by Cambridge University Press:  01 May 2009

Evan R. Phillips
Affiliation:
Department of Geology, University of Wollongong, P.O. Box 1144, Wollongong N.S.W. 2500, Australia

Summary

A brief review of Becke's (1908) replacement and Schwantke's (1909) exsolution models for myrmekite genesis and further consideration of the morphology and spatial distribution of myrmekite as outlined by Phillips (1974) lead to the conclusion that both hypotheses have a place in explaining the origin of myrmekite. The Schwantke model is generallybest applied, for example, to high-level undeformed massive granitoids and the Becke model to deformed metamorphic rocks. The latter hypothesis and a third model involving interaction between exsolution and replacement (Ashworth, 1972) may be used especially to explain the association of muscovite and myrmekite in rocks whose mineral assemblages have undergone retrograde modification, involving either redistribution of Na, Ca and K by local metasomatic reactions among the mineral grains, or metasomatic change of bulk rock composition.

Type
Articles
Copyright
Copyright © Cambridge University Press 1980

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References

Ashworth, J. R. 1972. Myrmekites of exsolution and replacement origins. Geol. Mag. 109, 4562.CrossRefGoogle Scholar
Ashworth, J. R. 1973. Myrmekites of exsolution and replacement origins – a discussion. Geol. Mag. 110, 7780.Google Scholar
Barker, D. S. 1970. Compositions of granophyre, myrmekite, and graphic granite. Bull. geol. Soc. Am. 81, 3339–50.CrossRefGoogle Scholar
Becke, F. 1908. Über Myrmekit. Min. Pet. Mitt. 27, 377–90.Google Scholar
Binns, R. A. 1966. Granitic intrusions and regional metamorphic rocks of Permian age from the Wongwibinda district, north-eastern New South Wales. J. Proc. R. Soc. New South Wales 99, 536.CrossRefGoogle Scholar
Byerly, G. R. & Vogel, T. A. 1973. Grain boundary processes and development of metamorphic plagioclase. Lithos 6, 183202.CrossRefGoogle Scholar
Chenhall, B. E., Pemberton, J. W., Phillips, E. R. & Stone, I. J. 1977. The lower quartzofeldspathic gneiss at Broken Hill, New South Wales. Mineralog. Mag. 41, M20.CrossRefGoogle Scholar
Drescher-Kaden, F. K. 1948. Die Feldspat-Quarz-Reaktionsgefüge der Granite und Gneise und ihre genetische Bedeutung. Berlin: Springer-Verlag.CrossRefGoogle Scholar
Hubbard, F. H. 1966. Myrmekite in charnockite from southwest Nigeria. Am. Miner. 51, 762–73.Google Scholar
Nockolds, S. R., Knox, R. W. O'B. & Chinner, G. A. 1978. Petrology for Students. Cambridge: Cambridge University Press.Google Scholar
Phillips, E. R. 1964. Myrmekite and albite in some granites of the New England Batholith, New South Wales. J. geol. Soc. Aust. 11, 4960.CrossRefGoogle Scholar
Phillips, E. R. 1973. Myrmekites of exsolution and replacement origins – a discussion. Geol. Mag. 110, 74–7.CrossRefGoogle Scholar
Phillips, E. R. 1974. Myrmekite – one hundred years later. Lithos 7, 181–94.CrossRefGoogle Scholar
Phillips, E. R. & Carr, G. R. 1973. Myrmekite associated with alkali feldspar megacrysts in felsic rocks from New South Wales. Lithos 6, 245–60.CrossRefGoogle Scholar
Phillips, E. R. & Ransom, D. M. 1968. The proportionality of quartz in myrmekite. Am. Miner. 53, 1411–13.Google Scholar
Phillips, E. R. & Ransom, D. M. 1970. Myrmekitic and non-myrmekitic plagioclase compositions in gneisses from Broken Hill, New South Wales. Mineralog. Mag. 37, 729–32.CrossRefGoogle Scholar
Phillips, E. R., Ransom, D. M. & Vernon, R. H. 1972. Myrmekite and muscovite developed by retrograde metamorphism at Broken Hill, New South Wales. Mineralog. Mag. 38, 570–8.CrossRefGoogle Scholar
Phillips, E. R. & Stone, I. J. 1974. Reverse zoning between myrmekite and albite in a quartzofeldspathic gneiss from Broken Hill, New South Wales. Mineralog. Mag. 39, 654–7.CrossRefGoogle Scholar
Schwantke, A. 1909. Die Beimischung von Ca im Kalifeldspat und die Myrmekitbildung. Zentbl. Miner. Geol. Paläont. pp. 311–16.Google Scholar
Sederholm, J. J. 1916. On synantetic minerals and related phenomena. Bull. Comm. Geol. Finlande 48.Google Scholar
Shelley, D. 1964. On myrmekite. Am. Miner. 49, 4152.Google Scholar
Shelley, D. 1969. The proportionality of quartz in myrmekite: a discussion. Am. Miner. 54, 982–4.Google Scholar
Spencer, E. 1945. Myrmekite in graphic granite and in vein perthite. Mineralog. Mag. 27, 7998.Google Scholar
Stephenson, N. C. N. & Hensel, H. D. 1978. A Precambrian fayalite granite from the south coast of Western Australia. Lithos 11, 209–18.CrossRefGoogle Scholar
Sugi, K. 1930. On the granitic rocks of Tsukuba District and their associated injection-rocks. Japanese J. Geol. Geog. 13, 29112.Google Scholar
Tuttle, O. F. 1952. Origin of the contrasting mineralogy of extrusive and plutonic salic rocks. J. Geol. 60, 107–24.CrossRefGoogle Scholar
Vernon, R. H. 1976. Metamorphic Processes. New York: John Wiley.Google Scholar
Widenfalk, L. 1969. Electron micro-probe analyses of myrmekite plagioclasesand coexisting feldspars. Lithos 2, 295309.CrossRefGoogle Scholar