Hostname: page-component-cd9895bd7-dzt6s Total loading time: 0 Render date: 2024-12-28T01:59:02.522Z Has data issue: false hasContentIssue false
  • English
  • Français

Metamorphic differentiation; a mechanism indicated by zoned kyanite crystals in some rocks from the Lukmanier region, Switzerland

Published online by Cambridge University Press:  05 July 2018

M. G. Bramwell
M. G. Bramwell*
Affiliation:
Department of Geology, Queen's University, Belfast BT7 1NN
Get access Rights & Permissions [Opens in a new window]

Abstract

Two samples of garnet-kyanite-staurolite schist from Lukmanier, Switzerland, each contain two chemical varieties of kyanite which occur in texturally distinct areas of the rock. Type 1 form large idiomorphic crystals within an open crenulation cleavage S3. They exhibit a systematic zonation of F2O3, with core values of 0.8% decreasing to 0.3% at the crystal margin. Type 2 form small, much less abundant crystals in areas between S3 cleavage zones, and have a homogeneous distribution of 0.3% Fe2O3 throughout the crystal.

It is suggested that the first-nucleated crystals contain the highest core concentration of Fe2O3 and are the largest. A positive correlation between core Fe2O3 values and crystal size is interpreted as a nucleation and growth sequence. This indicates that the first crystals formed preferentially in S3 (Type 1), with Type 2 crystals growing later outside the S3 zones.

Concentration of kyanite in S3 zones produces a distinct mineral banding in the rock. A mechanism for the development of metamorphic differentiation by preferred nucleation of kyanite in S3 is proposed.

Keywords

metamorphic differentiationkyaniteschistLukmanier regionSwitzerland
Type
Research Article
Information
Mineralogical Magazine , Volume 49 , Issue 350 , March 1985 , pp. 59 - 64
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1985 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Anderson, D. E., and Buckley, G. R. (1973) Contrib. Mineral. Petrol. 40, 87–104.Google Scholar
Bennington, K. O. (1965) J. Geol. 64, 558-77.Google Scholar
Carpenter, J. R. (1968) Contrib. Mineral. Petrol. 17, 173-86.Google Scholar
Chadwick, B. (1968) Bull. geol. Soc. Am. 79, 1123-50.Google Scholar
Dee, W. A., Howie, R. A., and Zussman, J. (1982) Rock-forming minerals, Vol. IA. Longmans, London.Google Scholar
Eskola, P. (1932) Bull. Comm. Geol. Finl. 97, 68.Google Scholar
Finlay, C. A., and Kerr, A. (1979) Contrib. Mineral. Petrol. 71, 185-91.Google Scholar
Fox, J. S. (1975) Geol. Mag. 112, 547–626.Google Scholar
Frey, M. (1969) Bietr. geol. Karte schwiez Neue Folge, 137, 160 pp.Google Scholar
Ghaly, T. S. (1969) Contrib. Mineral. Petrol. 22, 276-89.Google Scholar
Gray, D. R. (1977) Lithos, 10, 89–101.Google Scholar
Kretz, R. (1974) Ibid. 3, 123-31.Google Scholar
Niggli, E. (1970) Fortschr. Mineral. 47, 16–26.Google Scholar
Niggli, P. (1929) Schwiez. Mineral. Petrogr. Mitt. 9, 160-87.Google Scholar
Ramberg, H. (1952) Origin of igneous and metasomatic rocks. Univ. Chicago Press.Google Scholar
Sander, B. (1930) Einfuhrung in die Gefugekunde der geologischen Korper. Springer, Berlin, 1st edn.Google Scholar
Schmidt, W. (1932). Tektonik und Verformungslehre. Barnstraeger, Berlin.Google Scholar
Spry, A. (1969) Metamorphic textures. Pergamon Press Ltd.Google Scholar
Stillwell, F. L. (1918) Antarctic Expedition Sci. Repts. a, 3, 1.Google Scholar
Talbot, J. L., and Hobbs, B. E. (1968) J. Geol. 76, 581-87.Google Scholar
Turner, F. J. (1941) Am. J. Sci. 239, 1.Google Scholar