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An Acadian mountain front in the English Lake District: the Westmorland Monocline

Published online by Cambridge University Press:  01 May 2009

B. C. Kneller  and
A. M. Bell
B. C. Kneller
Affiliation:
Department of Earth Sciences, The University, Liverpool L69 3BX, U.K.
A. M. Bell
Affiliation:
Department of Earth Sciences, The Open University, Milton Keynes MK7 6BT, U.K.
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Abstract

The structure of the southern and central English Lake District is that of a southeast-facing monocline, named here the Westmorland Monocline. This 10 km wide zone of highly cleaved, southeast-dipping rocks separates gently dipping, poorly cleaved Borrowdale Volcanic Group to the north from extensively folded but regionally subhorizontal Windermere Group (foreland basin) rocks to the south. The monocline formed early in the local Acadian deformation sequence, and accommodates at least 8 km of uplift. It coincides with the steep concealed margin of the Lake District batholith. A major northwest-dipping shear zone is revealed in the deepest levels now exposed within the monocline, in the Skiddaw Group rocks of the Black Combe inlier.

The monocline has the characteristics of a mountain front, providing significant tectonic elevation across a foreland-dipping panel of rocks, with no hinterland-dipping thrust visible at the surface. We interpret the uplift as the consequence of a southeast-vergent thrust with a gently northwest-dipping ramp beneath the central Lake District, continuing southeastwards as a flat detachment beneath the Windermere Group. A displacement up the ramp of about 20 km is accommodated by backthrusting within the monocline and by shortening within the Windermere Group of the hangingwall southeast of the monocline. The tip lies beyond the limit of the Lower Palaeozoic inlier, beneath Carboniferous cover.

Type
Articles
Information
Geological Magazine , Volume 130 , Issue 2 , March 1993 , pp. 203 - 213
Copyright
Copyright © Cambridge University Press 1993

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References

Arthurton, R. S., Johnson, E. W. & Mundy, D. J. C. 1988. Geology of the country around Settle. Memoir of the British Geological Survey, Sheet 60 (England and Wales).Google Scholar
Arthurton, R. S. & Wadge, A. J. 1981. Geology of the country around Penrith. Memoir of the Institute of Geological Sciences, Sheet 24 (England and Wales).Google Scholar
Bell, A. M. 1981. Strain factorizations from lapilli tuff, English Lake District. Journal of the Geological Society 138, 463–74.CrossRefGoogle Scholar
Bott, M. H. P. 1974. The geological interpretation of a gravity survey of English Lake District and the Vale of Eden. Journal of the Geological Society 130, 309–31.CrossRefGoogle Scholar
Bott, M. H. P. 1978. Deep structure. In The Geology of the Lake District (ed. Moseley, F.), pp. 25–40. Yorkshire Geological Society, Occasional Publication no. 3.Google Scholar
Boulter, C. A. & Soper, N. J. 1973. Structural relationships of the Shap granite. Proceedings of the Yorkshire Geological Society 39, 365–9.CrossRefGoogle Scholar
Branney, M. J. 1988. The subaerial setting of the Ordovician Borrowdale Volcanic Group, English Lake District. Journal of the Geological Society 145, 887–90.CrossRefGoogle Scholar
Branney, M. J. 1991. Eruption and depositional facies of the Whorneyside Tuff Formation, English Lake District: an exceptionally large-magnitude phreatoplinian eruption. Geological Society of America Bulletin 203, 886–97.2.3.CO;2>CrossRefGoogle Scholar
Branney, M. J. & Soper, N. J. 1988. Ordovician volcanotectonics in the English Lake District. Journal of the Geological Society 145, 367–76.CrossRefGoogle Scholar
Capewell, J. G. 1955. The post-Silurian, pre-marine Carboniferous rocks of the eastern side of the English Lake District. Quarterly Journal of the Geological Society of London 111, 23–46.CrossRefGoogle 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 145, 523–40.CrossRefGoogle Scholar
Elliott, D. 1976. The motion of thrust sheets. Journal of Geophysical Research 81, 949–63.CrossRefGoogle Scholar
Firman, R. J. & Lee, M. K. 1986. The age and structure of the English Lake District batholith and its probable influence on subsequent sedimentation, tectonics and mineralisation. In Geology in the Real World-The Kingsley Dunham Volume (eds Nesbitt, R. W. and Nichol, I.), pp. 117–27. London: Institution of Mining and Metallurgy.Google Scholar
Freeman, B., Klemperer, S. L. & Hobbs, R. W. 1988. The deep structure of northern England and the Iapetus suture zone from BIRPS deep seismic reflection profiles. Journal of the Geological Society 145, 727–40.CrossRefGoogle Scholar
Furness, R. R. 1965. The petrography and provenance of the Coniston Grits east of the Lune valley, Westmorland. Geological Magazine 102, 252–60.CrossRefGoogle Scholar
Hatcher, R. D. Jr,. 1988. The third synthesis: Wenlock to mid-Devonian (end of Acadian orogeny). In The Caledonian-Appalachian Orogen (eds Harris, A. L. and Fettes, D. J.), pp. 499–504. Special Publication, Geological Society of London no. 38.Google Scholar
Hudleston, P. J. 1973. Fold morphology and some geometrical implications of theories of fold development. Tectonophysics 16, 1–46.CrossRefGoogle Scholar
Ingham, J. K. & McNamara, K. J. 1978. The Coniston Limestone Group. In The Geology of the Lake District (ed. F. Moseley), pp. 121–9. Yorkshire Geological Society, Occasional Publication no. 3.Google Scholar
Kneller, B. C. 1990 a. The Wenlock rocks of Sheet 38. British Geological Survey Technical Report WA/90/64.Google Scholar
Kneller, B. C. 1990 b. The Ludlow rocks of Sheet 38 (Ambleside). British Geological Survey Technical Report WA/90/62.Google Scholar
Kneller, B. C. 1991. A foreland basin on the southern margin of Iapetus. Journal of the Geological Society 148, 207–10.CrossRefGoogle Scholar
Kneller, B. C, Edwards, D. A., McCaffrey, W. A. & Moore, R. M. 1991. Oblique reflection of turbidity currents. Geology 14, 250–2.2.3.CO;2>CrossRefGoogle Scholar
Kneller, B. C. & Soper, N. J. 1990. Geology of SD39SE and SD39SW. British Geological Survey Technical Report WA/90/65.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 around Kentmere and Crook. Report of the British Geological Survey 18, no. 5.Google Scholar
Lee, M. K. 1989. Upper crustal structure of the Lake District from modelling and image processing of potential field data. British Geological Survey Technical Report WK/89/1.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 147, 241–58.CrossRefGoogle Scholar
McKerrow, W. S. 1988. The development of the Iapetus Ocean from the Arenig to the Wenlock. In The Caledonian-Appalachian Orogen (eds Harris, A. L. and Fettes, D. J.), pp. 405–12. Special Publication, Geological Society of London no. 38.Google Scholar
Millward, D. & Molyneux, S. D. 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
Molyneux, S. G. 1988. Micropalaeontological evidence for the age of the Borrowdale Volcanic Group. Geological Magazine 125, 541–2.CrossRefGoogle Scholar
Molyneux, S. G. & Rushton, A. W. A. 1984. Discovery of Tremadoc rocks in the Lake District. Proceedings of the Yorkshire Geological Society 45, 123–7.CrossRefGoogle Scholar
Moseley, F. & Millward, D. 1982. Ordovician vulcanicity in the English Lake District. In Igneous Rocks of the British Isles (ed. Sutherland, D. S.), pp. 83–111. London: Wiley.Google Scholar
Oliver, G. J. H. 1988. Arenig to Wenlock regional metamorphism in the Paratectonic Caledonides. In The Caledonian-Appalachian Orogen (eds Harris, A. L. and Fettes, D. J.), pp. 347–63. Special Publication, Geological Society of London no. 38.Google Scholar
Pidgeon, R. T. & Aftalion, M. 1978. Co-genetic and inherited zircon U-Pb systems in granites of Scotland and England. In Crustal Evolution in Northwest Britain and Adjacent Regions (eds Bowes, D. R. and Leake, B. E.), pp. 183–248. Geological Journal Special Issue no. 10.Google Scholar
Rickards, R. B. 1988. Base of the Silurian in the Lake District and Howgill Fells, Northern England. Bulletin of the Museum of Natural History (Geology) 43, 53–7.Google Scholar
Simpson, A. 1967. The stratigraphy and tectonics of the Skiddaw Slates and the relationship of the overlying Borrowdale Volcanic Series in part of the Lake District. Geological Journal 5, 391–418.CrossRefGoogle Scholar
Soper, N. J. & Higgins, A. K. 1990. Models for the Ellesmerian mountain front in North Greenland: a basin margin inverted by basement uplift. Journal of Structural Geology 12, 83–97.CrossRefGoogle Scholar
Soper, N. J. & Kneller, B. C. 1990. Cleaved microgranite dykes of the Shap swarm in the Silurian of north-west England. Geological Journal 25, 161–70.CrossRefGoogle Scholar
Soper, N. J. & Moseley, F. 1978. Structure. In The Geology of the Lake District (ed. Moseley, F.), pp. 45–67. Yorkshire Geological Society, Occasional Publication no. 3.Google Scholar
Soper, N. J. & Numan, N. M. S. 1974. Structure and stratigraphy of the Borrowdale Volcanic rocks of the Kentmere area, English Lake District. Geological Journal 9, 147–66.CrossRefGoogle 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.CrossRefGoogle 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 42, 297–305.Google Scholar
Vann, I. R., Graham, H. R. & Hayward, A. B. 1986. The structure of mountain fronts. Journal of Structural Geology 8, 215–28.CrossRefGoogle Scholar
Wadge, A. J. 1978. Lower Ordovician rocks. In The Geology of the Lake District (ed. Moseley, F.), pp. 68–78. Yorkshire Geological Society, Occasional Publication no. 3.Google Scholar
Wadge, A. J., Nutt, M. J. C. & Skevington, D. 1972. Geology of the Tarn Moor tunnel in the Lake District. Bulletin of the Geological Survey of Great Britain 41, 55–73.Google Scholar
Webb, B. C. & Cooper, A. H. 1988. Slump folds and gravity slide structures in a Lower Palaeozoic marginal basin sequence (the Skiddaw Group), NW England. Journal of Structural Geology 10, 463–72.CrossRefGoogle Scholar