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The thrust structures of southern Assynt, Moine thrust zone

Published online by Cambridge University Press:  01 May 2009

M. P. Coward
M. P. Coward
Affiliation:
Geology Department, Imperial College, Prince Consort Road, London SW7 2BP, U.K.
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Abstract

The Moine thrust zone of southern Assynt forms part of the northwest margin of the Caledonide belt and has aroused controversy concerning amounts and timing of thrust displacement and sequence of thrust development. Recent mapping shows it to have been a foreland propagating thrust sequence; the uppermost ductile Moine thrust formed first, followed by sequences of imbricates, a major thrust (the Ben More thrust) and then several lower duplex zones. This sequence is clear from new observations that many of the earlier thrusts were folded and/or breached during the development of the underlying structures. A displacement of over 54 km has been estimated for the zone as a whole. An alkaline igneous complex, including the large Borrolan syenite, was intruded during the development of the thrust zone and much of it was carried some 30 km to the west-northwest onto the foreland. Late extensional structures in southern Assynt are an integral part of the Caledonide thrust sequence and probably developed from the collapse of the thrust wedge as it climbed from stronger basement rocks on to a weaker cover sequence on the foreland.

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Articles
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Geological Magazine , Volume 122 , Issue 6 , November 1985 , pp. 595 - 607
Copyright
Copyright © Cambridge University Press 1985

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References

Bailey, E. B. 1935. The Glencoul Nappe and the Assynt Culmination. Geological Magazine 72, 151–65.CrossRefGoogle Scholar
Boyer, S. & Elliott, D. 1982. Thrust systems. American Association of Petroleum Geologists 66, 1196–230.Google Scholar
Butler, R. W. H. 1982. The terminology of structures in thrust belts. Journal of Structural Geology 4, 239–45.CrossRefGoogle Scholar
Butler, R. W. H. 1984. Balanced cross-sections and their implication for the deep geology of the north-west Alps: reply. Journal of Structural Geology 6, 607–12.CrossRefGoogle Scholar
Butler, R. W. H. & Coward, M. P. 1984. Geological constraints, structural evolution and deep geology of the Northwest Scottish Caledonides. Tectonics 3, 347–65.CrossRefGoogle Scholar
Christie, J. M. 1960. Mylonitic rocks of the Moine thrust zone of NW Scotland. Transactions of the Edinburgh Geological Society 18, 79–93.CrossRefGoogle Scholar
Christie, J. M. 1963. The Moine thrust zone in the Assynt region, north-west Scotland. University of California Publications,Geological Sciences 40, 345–440.Google Scholar
Coward, M P. 1982. Surge zones in the Moine thrust zone of NW Scotland. Journal of Structural Geology 4, 247–56.CrossRefGoogle Scholar
Coward, M. P. 1983. The thrust and shear zones of the Moine thrust zone and the NW Scottish Caledonides. Journal of the Geological Society of London 140, 795–811.CrossRefGoogle Scholar
Coward, M. P. 1984 a. The strain and textural history of thin-skinned tectonic zones: examples from the Assynt region of the Moine thrust zone, N.W. Scotland. Journal of Structural Geology 6, 89–100.CrossRefGoogle Scholar
Coward, M. P. 1984 b. Moine Thrust Zone. In Geological Synthesis of the Caledonide Rocks of the U.K. (ed. Fettes, D. J. and Harris, A. L.), pp. 177–215. Nato Advanced Studies Institute 984/83, Field Guide.Google Scholar
Coward, M. P., Kim, J. H. & Parke, J. 1980. The Lewisian structures within the Moine thrust zone. Proceedings of the Geological Association 91, 327–37.CrossRefGoogle Scholar
Dahlstrom, C. D. A. 1970. Structural geology of the eastern margin of the Canadian Rocky Mountains. Bulletin of Canadian Petroleum Geologists 18, 332–406.Google Scholar
Davis, D., Suppe, J. & Dahlen, F. A. 1983. Mechanics of fold and thrust belts and accretionary wedges. Journal of Geophysical Research 88, 1153–78.CrossRefGoogle Scholar
Elliott, D. & Johnson, M. R. W. 1980. Structural evolution of the northern part of the Moine thrust zone, N.W. Scotland. Transactions of the Royal Society of Edinburgh 71, 69–96.CrossRefGoogle Scholar
Hossack, J. R. 1979. The use of balanced cross sections in the calculation of erogenic contraction, a review. Journal of the Geological Society of London 136, 705–11.CrossRefGoogle Scholar
Johnson, M. R. W. & Parsons, I. 1979. Geological Excursion Guide to the Assynt District of Sutherland. Edinburgh Geological Society. 76pp.Google Scholar
Law, R. D., Casey, M. & Knipe, R. J. 1985. The kinematic and tectonic significance of microstructural and crystallographic fabrics within quartz mylonites from the Assynt and Eriboll regions of the Moine thrust zone, North-west Scotland. Transactions of the Royal Society of Edinburgh (in press).CrossRefGoogle Scholar
Pankhurst, R. J. 1982. Geochronological tables for British igneous rocks. In Igneous Rocks of the British Isles (ed. Sutherland, D. S.), pp. 575–81. John Wiley.Google Scholar
Parsons, I. 1979. The Assynt alkaline suite. In The British Caledonides Reviewed (ed. Harris, A. L., Holland, C. H. & Leake, B. E.), pp. 677–81. Special Publication of the Geological Society of London no. 8.Google Scholar
Parsons, I. & McKirdy, A. P. 1983. Inter-relationship of igneous activity and thrusting in Assynt: excavations at Borralan. Scottish Journal of Geology 19, 59–66.CrossRefGoogle Scholar
Peach, B. N., Horne, J., Gunn, W., Clough, C. T., Hinxman, L. W. & Teall, J. J. H. 1907. The Geological Structure of the Northwest Highlands of Scotland. Memoir. Geological Survey of the United Kingdom.Google Scholar
Platt, J. 1984. Balanced cross-sections and their implications for the deep structure of the northwest Alps: discussion. Journal of Structural Geology 6, 603–6.CrossRefGoogle Scholar
Read, H. H., Phemister, J. & Ross, G. 1926. The Geology of Strath Oykell and Lower Loch Shin. Memoir. Geological Survey of the United Kingdom.Google Scholar
Sabine, P. A. 1953. The petrography and geological significance of the post-Cambrian minor intrustions of Assynt and the adjoining districts of North-west Scotland. Quarterly Journal of the Geological Society of London 109, 137–69.CrossRefGoogle Scholar
Swett, K. 1969. Interpretation of depositional and diagenetic history of Cambro-Ordovician succession of Northwest Scotland. In North Atlantic – Geology and Continental Drift. (ed. Kay, M.), pp. 630–46. Memoir, American Association of Petrolium Geologists no. 12.Google Scholar
Van Breeman, O., Aftalion, M. & Johnson, M. R. W. 1979. Age of the Loch Borralan complex, Assynt and late movements on the Moine thrust. Journal of the Geological Society of London 136, 489–96.CrossRefGoogle Scholar
Woolley, A. R. 1970. The structural relationships of the Loch Borrolan complex, Scotland. Geological Journal 7 171–82.CrossRefGoogle Scholar
Woolley, A. R. 1973. The pseudo-leucite borolanites and associated rocks of the south-eastern tract of the Borralan complex, Scotland. Bulletin of the British Museum (Natural History) 2.Google Scholar