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Relationship between metamorphism and structure in the Skiddaw Group, English Lake District

Published online by Cambridge University Press:  01 May 2009

N. J. Fortey ,
B. Roberts  and
S. R. Hirons
N. J. Fortey
Affiliation:
British Geological Survey, Keyworth, Nottingham NG12 5GG, U.K.
B. Roberts
Affiliation:
Department of Geology, Birkbeck College, Malet Street, London WC1E 7HX, U.K.
S. R. Hirons
Affiliation:
Department of Geology, Birkbeck College, Malet Street, London WC1E 7HX, U.K.
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Abstract

Regional variation of white mica (illite) crystallinity in the Skiddaw Group is set against the structural interpretation of Hughes, Cooper & Stone (1993, this issue) in which early- or pre-Ludlow deformation and slaty cleavage development (S1) were succeeded by southward thrusting and an associated development of S1 and S1 crenulation cleavages, possibly during early Devonian times. Kubier index (KI) values are plotted in relation to geological structure for a major part of the Skiddaw Group, and cross-sections constructed. The pattern is interpreted in terms of three processes: (1) diagenetic to low anchizonal burial metamorphism under a relatively high geothermal gradient during the late-arc stage (early to mid-Silurian) which preceded the orogenic phase and formation of S1; (2) upper anchizonal to epizonal metamorphism due to tectonic thickening and slaty cleavage development during the early to pre-Ludlow orogenic phase following closure of Iapetus; (3) late-tectonic uplift of already metamorphosed rocks by southward-directed movement on the Loweswater, Gasgale Gill and Causey Pike Thrusts possibly during early Devonian time. An analogous interpretation is made for the Skiddaw area, though with the addition of major post-S1 contact metamorphism.

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Articles
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Geological Magazine , Volume 130 , Issue 5 , September 1993 , pp. 631 - 638
Copyright
Copyright © Cambridge University Press 1993

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References

Allen, P. A. & Allen, J. R. 1990. Basin analysis – sedimentary basins. Blackwell Scientific, 352 pp.Google Scholar
Bergström, S. M. 1980. Conodonts as palaeotemperature tools in Ordovician rocks of the Caledonides and adjacent areas in Scandinavia and the British Isles. Geologiska Foreningens i Stockholm Forhandlingar 102, 377–92.CrossRefGoogle Scholar
Bottrell, S. H., Greenwood, P. B., Yardley, B. W. D., Shepherd, T. J. & Spiro, B. 1990. Metamorphic and post-metamorphic fluid flow in the low-grade rocks of the Harlech Dome, North Wales. Journal of Metamorphic Geology 8, 131–43.CrossRefGoogle Scholar
British Geological Survey, 1990. Lorton and Loweswater, 1:25000 Series, Sheet NY 12.Google Scholar
Cooper, A. H. & Molyneux, S. G. 1990. The age and correlation of Skiddaw Group (early Ordovician) sediments in the Cross Fell inlier (northern England). Geological Magazine 127, 147–57.Google Scholar
Cooper, D. C., Lee, M. K., Fortey, N. J., Cooper, A. H., Rundle, C. C., Webb, B. C. & Allen, P. M. 1988. The Crummock Water aureole: a zone of metasomatism and source of ore metals in the English Lake District. Journal of the Geological Society, London 145, 523–40.CrossRefGoogle Scholar
Eastwood, T., Hollingworth, S. E., Rose, W. C. C. & Trotter, F. M. 1968. Geology of the country around Cockermouth and Caldbeck. Memoir of the Geological Survey of Great Britian, Sheet 23.Google Scholar
Fitton, R. J. & Hughes, D. J. 1970. Volcanism and plate tectonics. Earth and Planetary Science Letters 8, 223–8.CrossRefGoogle Scholar
Fortey, N. J. 1989. Low grade metamorphism in the Lower Ordovician Skiddaw Group of the Lake District, England. Proceedings of the Yorkshire Geological Society 47, 325–37.Google Scholar
Frey, M. 1969. A mixed-layer paragonite/phengite of low-grade metamorphic origin. Contributions to Mineralogy and Petrology 24, 63–5.CrossRefGoogle Scholar
Hughes, R. A., Cooper, A. H. & Stone, P. 1993. The structural evolution of the Skiddaw Group (English Lake District) on the northern margin of eastern Avalonia. Geological Magazine 130, 621–9.Google Scholar
Kisch, H. J. 1987. Correlation between indicators of very low-grade metamorphism. In Low Temperature Metamorphism (ed. Frey, M.), pp. 227–304. Glasgow: Blackie & Sons.Google Scholar
Kisch, H. J. 1991. Development of slaty cleavage and degree of very low-grade metamorphism: a review. Journal of Metamorphic Geology 9, 735–50.Google Scholar
Kneller, B. C. 1991. A foreland basin on the southern margin of Iapetus. Journal of the Geological Society, London 148, 207–10.CrossRefGoogle Scholar
Kneller, B. C., King, L. M. & Bell, A. M. 1993. Foreland basin development and tectonics on the NW margin of Eastern Avalonia. Geological Magazine 130, 691–7.Google Scholar
Kubler, B. 1968. Evaluation quantitative du métamorphisme par la cristallinité de l'illite. Bulletin du Centre de Recherche Pau-SNPA 2, 385–97.Google Scholar
Lawrence, D. J. D., Webb, B. C., Young, B. & White, D. E. 1986. The geology of the Late Ordovician and Silurian Rocks (Windermere Group) in the area aroundKentmere and Crook. British Geological Survey Report 18, no. 5, 32 pp.Google Scholar
Lee, M. K. 1986. A new gravity survey of the Lake District and three-dimensional model of the granite batholith. Journal of the Geological Society, London 143, 425–36.Google Scholar
Lee, M. K., Pharaoh, T. C. & Soper, N. J. 1990. Structural trends in central Britain from images of gravity and aeromagnetic fields. Journal of the Geological Society, London 147, 241–58.CrossRefGoogle Scholar
Li, G., Jiang, W.-T. & Peacor, D. R. 1992. Metastable intermediate Na–K micas in hydrothermally altered metabasites and metamorphosed pelites from Wales. Geological Society of America, Abstracts with Programs, A72.Google Scholar
Merriman, R. J., Roberts, B. & Peacor, D. R. 1990. A transmission electron microscope study of white mica crystallite size distribution in a mudstone to slate transitional sequence, North Wales, UK. Contributions to Mineralogy and Petrology 106, 27–40.Google Scholar
Millward, D. & Molyneux, S. G. 1992. Field and biostratigraphic evidence for an unconformity at the base of the Eycott Volcanic Group in the English Lake District. Geological Magazine 129, 77–92.CrossRefGoogle Scholar
Millward, D., Moseley, F. & Soper, N. J. 1978. The Eycott and Borrowdale Volcanic Rocks. In The Geology of the Lake District (ed. Moseley, F.), pp. 99–120. Yorkshire Geological Society Occasional Publication no. 3.Google Scholar
Molyneux, S. G. & Rushton, A. W. A. 1988. The age of the Watch Hill Grits (Ordovician), English Lake District: structural and palaeogeographical implications. Transactions of the Royal Society of Edinburgh: Earth Sciences 79, 43–69.CrossRefGoogle Scholar
Oliver, G. J. H. 1988. Arenig to Wenlock regional meta-morphism in the paratectonic Caledonides of the British Isles: a review. In The Caledonian-Appalachian orogen (eds Harris, A. L. and Fettes, D. J.), pp. 347–63. Geological Society of London, Special Publication no. 38.Google Scholar
Oliver, G. J. H., Smellie, J. L., Thomas, L. J., Casey, D. M., Kemp, A. E. S., Evans, L. J., Baldwin, J. R. & Hepworth, B. C. 1984. Early palaeozoic metamorphic history of the Midland Valley, the Southern Uplands-Longford Down massif and the Lake District, British Isles. Transactions of the Royal Society of Edinburgh, Earth Sciences 75, 259–73.Google Scholar
Petterson, M. G., Beddoe-Stephens, B., Millward, D. & Johnson, E. W. 1992. A pre-caldera plateau-andesite field in the Borrowdale Volcanic Group of the English Lake District. Journal of the Geological Society, London 149, 889–906.Google Scholar
Roberts, B., Merriman, R. J. & Pratt, W. 1991. The influence of strain, lithology and stratigraphical depth on white mica (illite) crystallinity in mudrocks from the vicinity of the Corris Slate Belt, Wales: implications for the timing of metamorphism in the Welsh Basin. Geological Magazine 128, 633–45.Google Scholar
Roberts, B., Morrison, C. & Hirons, S. 1990. Low grade metamorphism of the Manx Group, Isle of Man: a comparative study of white mica ‘crystallinity’ techniques. Journal of the Geological Society, London 147, 271–77.Google Scholar
Roberts, D. E. 1976. Cleavage formation in the Skiddaw Slates of the Northern Lake District, England. Geological Magazine 113, 377–82.Google Scholar
Roberts, D. E. 1977. The structure of the Skiddaw Slates in the Blencathra–Mungrisedale area, Cumbria. Geological Journal 12, 33–58.Google Scholar
Rundle, C. C. 1979. Ordovician intrusions in the English Lake District. Journal of the Geological Society, London 136, 29–38.Google Scholar
Shepherd, T. J., Beckinsale, R. B., Rundle, C. C. & Durham, J. 1976. Genesis of Carrock Fell tungsten deposits, Cumbria: fluid inclusion and isotopie study. Transactions of the Institution of Mining and Metallurgy (Section B: Applied Earth Science) 85, 63–74.Google Scholar
Simpson, A. 1967. The stratigraphy and tectonics of the Skiddaw Slates and the relationship of the overlying Volcanic Series in part of the Lake District. Geological Journal 5, 391–418.Google Scholar
Soper, N. J. 1970. Three critical localities on the junction of the Borrowdale Volcanic rocks with the Skiddaw Slates in the Lake District. Proceedings of the Yorkshire Geological Society 37, 461–93.Google Scholar
Soper, N. J. & Kneller, B. C. 1990. Cleaved microgranite dykes of the Shap swarm in the Silurian of NW England. Geological Journal 25, 161–70.Google Scholar
Soper, N. J. & Roberts, D. E. 1971. Age of cleavage in the Skiddaw Slates in relation to the Skiddaw aureole. Geological Magazine 108, 293–302.Google Scholar
Soper, N. J., Webb, B. C. & Woodcock, N. H. 1987. Late Caledonian (Acadian) transpression in north-west England: timing, geometry and geotectonic significance. Proceedings of the Yorkshire Geological Society 46, 175–92.CrossRefGoogle Scholar
Soper, N. J. & Woodcock, N. H. 1990. Silurian collision and sediment dispersal patterns in southern Britain. Geological Magazine 127, 527–42.CrossRefGoogle Scholar
Wadge, A.J. 1972. Sections through the Skiddaw–Borrowdale unconformity in eastern Lakeland. Proceedings of the Yorkshire Geological Society 39, 179–98.Google Scholar
Wadge, A. J., Gale, N. H., Beckinsale, R. D. & Rundle, C. C. 1978. A Rb-Sr isochron age for the Shap granite. Proceedings of the Yorkshire Geological Society 42, 297–305.CrossRefGoogle Scholar
Webb, B. C. & Cooper, A. H. 1988. Slump folds and gravity slide structures in a Lower Palaeozoic marginal basin sequence (the Skiddaw Group), north-west England. Journal of Structural Geology 10, 463–72.CrossRefGoogle Scholar
Webb, P. C. & Brown, G. C. 1984. Lake District granites: heat production and related geochemistry. BGS Geothermal Resources Programme, 66 pp.Google Scholar
Weber, K. 1967. Notes on the determination of illite crystallinity. Neues Jahrbuch für Mineralogie 6, 267–76.Google Scholar