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A Study of Quartz Orientation and its Relation to Movement in Shear Folds

Published online by Cambridge University Press:  01 May 2009

P. K. Gangopadhyay  and
M. R. W. Johnson
P. K. Gangopadhyay
Affiliation:
Grant Institute of Geology, Edinburgh.
M. R. W. Johnson
Affiliation:
Grant Institute of Geology, Edinburgh.
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Abstract

The orientation of quartz in small shear folds, which belong to two movement episodes, is considered to result from laminar flow along the axial plane surfaces. The locations of fabric maxima and girdles are controlled by the orientation of the a–kinematic axis, which in shear folds may not be normal to the fold axis, and the shear surfaces. The earlier fabric consists, essentially, of paired maxima arranged systematically about the axial plane; ac–girdles are absent. The explanation of the near-orthorhombic symmetry of the first fabric in terms of a late “flattening” overprinted upon the previously-formed fold is not favoured: quartz orientation developed during the first folding. The later fabric results from the recrystallization of quartz grains with their largest dimensions and c–axes parallel to the calculated a–kinematic axis of second folding.

Type
Articles
Information
Geological Magazine , Volume 99 , Issue 1 , February 1962 , pp. 69 - 84
Copyright
Copyright © Cambridge University Press 1962

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References

REFERENCES

Carey, S. W., 1954. The Rheid Concept in Geotectonics. J. geol. Soc. Aust., 1, 67–117.CrossRefGoogle Scholar
Christie, J. M., 1956. Ph.D., Thesis University of Edinburgh.Google Scholar
de Sitter, L. U., 1956. Structural Geology. New York and London.Google Scholar
de Sitter, L. U., 1958. Boudins and Parasitic Folds in Relation to Cleavage and Folding. Geol. en Mijnb., 20, 277–286.Google Scholar
Harris, A. L., and Rast, N., 1960. The Evolution of Quartz Fabrics in the Metamorphic Rocks of Central Perthshire. Trans. Edinb. geol. Soc., 18, 51–78.CrossRefGoogle Scholar
Johnson, M. R. W., 1957. The Structural Geology of the Moine Thrust Zone in the Coulin Forest, Wester Ross. Quart. J. geol. Soc. Lond., 113, 241–270.CrossRefGoogle Scholar
Johnson, M. R. W., 1960. The Structural History of the Moine Thrust Zone at Lochcarron, Wester Ross. Trans. roy. Soc. Edinb., 64, 139–168.CrossRefGoogle Scholar
Ramsay, J. G., 1960. The Deformation of Early Linear Structures in Areas of Repeated Folding. J. Geol., 68, 75–93.CrossRefGoogle Scholar
Sander, B., 1930. Gefügekunde der Gesteine. Vienna.CrossRefGoogle Scholar
Sander, B., 1950. Einführung in die Gefügekunde der Geologischen Körper. Zweiter Teil. Vienna–Innsbruck.CrossRefGoogle Scholar
Sahama, T. G., 1936. Die Regel von Quartz und Glimmer in den Gesteinen der Finnisch Lappländischen Granulitformation. Bull. Comm. geol. Finl., 113, 1–119.Google Scholar
Weiss, L. E., 1954. A Study of Tectonic Style. Univ. Calif. Publ. Geol. Sci., 30, 1–102.Google Scholar
Weiss, L. E., 1959. Geometry of Superposed Folding. Bull. geol. Soc. Amer., 70, 91–106.CrossRefGoogle Scholar