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Polyphase fold analysis of gneisses and migmatites

Published online by Cambridge University Press:  03 November 2011

A. M. Hopgood
A. M. Hopgood
Affiliation:
Department of Geology, University of St Andrews, St Andrews, Fife KY16 9ST, Scotland.
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Abstract

In spite of the structural complexity of polyphase deformed gneisses and migmatites and the absence of distinctive marker horizons, these rocks are amenable to structural investigation and interpretation with resolution of their tectonic history possible, particularly in regions of reasonable exposure. Although methods such as those employing interpretation of stereo-plots can seldom be used, direct observation of refold relationships on the outcrop using all available structural, igneous and metamorphic features will ultimately lead to the resolution of the deformational history. This is achieved by determining the relationships of fold sets observed at the various localities examined throughout the field of investigation and then combining these by correlation according to basic stratigraphical principles. The effects of weak deformation normally not discernible in complicated successions may be detected by the simple form of folded planar and linear structures in igneous masses emplaced in complex structures at intermediate stages in the deformational history.

Synthesis of the total succession and determination of the overall sequence of deformation in particularly complex terranes is made easier if at least one distinctive set of structures can be recognised throughout the area. These key structures have the effect of subdividing the long succession into two in which refold relationships are generally more easily determined. An example of the method is given using photographs from the migmatite terrane in southern Finland.

Keywords

CorrelationmetamorphismorogenyPrecambrianrefoldingtectonism
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 71 , Issue 1 , 1980 , pp. 55 - 68
Copyright
Copyright © Royal Society of Edinburgh 1980

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References

Bell, T. H. 1978. Progressive deformation and reorientation of fold axes in a ductile mylonite zone: The Woodroffe Thrust. TECTONOPHYSICS 44, 285–320.Google Scholar
Bell, T. H. & Duncan, A. C. 1978. A rationalised and unified shorthand terminology for lineations and fold axes in tectonites. TECTONOPHYSICS 47, T1–5.CrossRefGoogle Scholar
Berthelsen, A., Bondesen, E. & Jensen, S. B. 1962. On the so-called wild migmatites. KRYSTALINIKUM 1, 31–49.Google Scholar
Bhattacharjee, C. C. 1968. The structural history of the Lewisian rocks north-west of Loch Tollie, Ross-shire, Scotland. SCOTT J GEOL 4, 235–63.CrossRefGoogle Scholar
Borradaile, G. L. 1978. Transected folds: A study illustrated with examples from Canada and Scotland. BULL GEOL SOC AM 89, 481–93.2.0.CO;2>CrossRefGoogle Scholar
Bowes, D. R. 1976. Tectonics in the Baltic Shield in the period 2000–1500 million years ago. ACTA GEOL POL 26, 355–76.Google Scholar
Bowes, D. R. & Hopgood, A. M. 1969. The Lewisian gneiss complex of Mingulay, Outer Hebrides, Scotland. In Larsen, L. H. (ed.) Igneous and Metamorphic Geology, 317–56. MEM GEOL SOC AM 115.Google Scholar
Bowes, D. R., Hopgood, A. M. & Taft, M. B. 1971. Granitic injection complex of Harris, Outer Hebrides. SCOTT J GEOL 7, 289–91.Google Scholar
Dash, B. 1969. Structure of the Lewisian rocks between Strath Dionard and Rhichonich, Sutherland, Scotland. SCOTT J GEOL 5, 347–74.CrossRefGoogle Scholar
Edelman, E. 1960. The Gullkrona Region, SW Finland. BULL COMM GEOL FINL 187.Google Scholar
Gaál, G., Koistinen, T. & Mattila, E. 1975. Tectonics and stratigraphy of the vicinity of Outokumpu, North Karelia, Finland. GEOL SURV FIN BULL 271.Google Scholar
Ghosh, S. K. & Ramberg, H. 1968. Buckling experiments on intersecting fold patterns. TECTONOPHYSICS 5, 89–105.CrossRefGoogle Scholar
Hendry, H. E. & Stauffer, M. R. 1977. Penecontemporaneous folds in cross-bedding: Inversion of facing criteria and mimicry of tectonic folds. BULL GEOL SOC AM 88, 809–12.Google Scholar
Hobbs, B. E., Means, W. D. & Williams, P. F. 1976. An outline of structural geology. New York: Wiley.Google Scholar
Holland, J. G. & Lambert, R. St J. 1969. Structural regimes and metamorphic facies. TECTONOPHYSICS 7, 197–217.Google Scholar
Hopgood, A. M. 1968. The structural geology and tectonic history of Precambrian rocks exposed in the Kinarsani River, eastern Andhra Pradesh. J INDIAN GEOSCI ASSOC 8, 13–34.Google Scholar
Hopgood, A. M. 1970. Structural reorientation as evidence of basement warping associated with rift faulting in Uganda. BULL GEOL SOC AM 81, 3473–80.Google Scholar
Hopgood, A. M. 1971a. Structural and tectonic history of Lewisian Gneiss, Isle of Barra, Scotland. KRYSTALINIKUM 7, 27–60.Google Scholar
Hopgood, A. M. 1971b. Correlation by tectonic sequence in Precambrian gneiss terrains. SPEC PUBL GEOL SOC AUST 3, 367–76.Google Scholar
Hopgood, A. M. 1973. The significance of deformational sequence in discriminating between Precambrian terrains. SPEC PUBL GEOL SOC AFR 3, 45–51.Google Scholar
Hopgood, A. M. 1976. Structures in an area north-east ol Fiskenaesset, West Greenland. RAPP GRONLANDS GEOL UNDERS 73, 16–21.Google Scholar
Hopgood, A. M. & Bowes, D. R. 1972a. Application of structural sequence to the correlation of Precambrian gneisses, Outer Hebrides, Scotland. BULL GEOL SOC AM 83, 107–28.Google Scholar
Hopgood, A. M. & Bowes, D. R. 1972b. Correlation by structural sequence in Precambrian gneiss of north-western British Isles. 24th INT GEOL CONGR 1, 195–200.Google Scholar
Hopgood, A. M. & Bowes, D. R. 1976. Polyphase agmatites as time markers in complexly deformed gneisses. 25th INT GEOL CONGR ABSTR 3, 665.Google Scholar
Hopgood, A. M. & Bowes, D. R. 1978. Neosomes of polyphase agmatites as time-markers in complexly deformed migmatites. GEOL RUNDSCH 67, 313–30.CrossRefGoogle Scholar
Hopgood, A. M. & Bowes, D. R. 1980. Structural analysis of folded cooling joints in a near-concordant minor intrusion. GEOL RUNDSCH 69 (in press).Google Scholar
Hopgood, A. M., Bowes, D. R. & Addison, J. 1976. Structural development of migmatites near Skåldö, southwest Finland. BULL GEOL SOC FINL 48, 43–62.CrossRefGoogle Scholar
Joubert, P. 1971. The regional tectonism of the gneisses of part of Namaqualand. BULL PRECAMBRIAN RES UNIT UNIV CAPETOWN 10.Google Scholar
Laing, W. P., Marjoribanks, R. W. & Rutland, R. W. R. 1978. Structure of the Broken Hill Mine area and its significance for the genesis of the orebodies. ECON GEOL 73, 1112–36.Google Scholar
Lyon, T. D. B., Pidgeon, R. T., Bowes, D. R. & Hopgood, A. M. 1973. Geochronological investigation of the quartzofeldspathic rocks of the Lewisian of Rona, Inner Hebrides. J GEOL SOC LONDON 129, 389–404.Google Scholar
Naha, K. & Mukherji, P. 1969. Analysis of large scale superposed folding in a migmatite terrain. GEOL MIJNBOUW 48, 9–34.Google Scholar
Park, R. G. 1969. Structural correlation in metamorphic belts. TECTONOPHYSICS 7, 323–38.CrossRefGoogle Scholar
Pidgeon, R. T. & Hopgood, A. M. 1975. Geochronology of Archaean gneisses and tonalites from north of Frederikshåbs Isblink, S. W. Greenland. GEOCHIM COSMOCHIM ACTA 39, 1333–46.CrossRefGoogle Scholar
Ramsay, D. M. 1979. Analysis of rotation of folds during progressive deformation. BULL GEOL SOC AM 90, 732–8.2.0.CO;2>CrossRefGoogle Scholar
Ramsay, J. G. 1967. Folding and Fracturing of Rocks. New York: McGraw-Hill.Google Scholar
Sander, B. 1911. Über Zusammenhänge zwischen Teilbewegungen und Gefüge in Gesteine. TSCHERMAKS MINERAL PETROGR MITT 30, 287–314.Google Scholar
Sander, B. 1970. An Introduction to the Study of Fabrics of Geological Bodies (translated by Phillips, F. C. & Windsor, G.). New York; Pergamon Press.Google Scholar
Sederholm, J. J. 1967. Selected works: granites and migmatites. Edinburgh: Oliver and Boyd.Google Scholar
Sutton, J. 1973. In discussion of Hopgood, A. M. The significance of deformational sequence in discriminating between Precambrian terrains. SPEC PUBL GEOL SOC S AFR 3, 50–1.Google Scholar
Tobisch, O. T., Fleuty, M. J., Merh, S. S., Mukhopadhyay, D. & Ramsay, J. G. 1970. Deformation and metamorphic history of Moinian and Lewisian rocks between Strathconan and Glen Affric. SCOTT J GEOL 6, 243–65.Google Scholar
Turner, F. J. & Weiss, L. E. 1963. Structural analysis of metamorphic tectonites. New York: McGraw-Hill.Google Scholar
Watkinson, A. J. & Cobbold, P. R. 1978. Localization of minor folds by major folds. BULL GEOL SOC AM 89, 448–50.Google Scholar
Williams, P. F. 1970. A criticism of the use of style in the study of deformed rocks. BULL GEOL SOC AM 81, 3283–96.CrossRefGoogle Scholar
Williams, P. F. 1972. Development of metamorphic layering and cleavage in low grade metamorphic rocks at Bermagui, Australia. AM J SCI 272, 1–47.Google Scholar