Hostname: page-component-586b7cd67f-gb8f7 Total loading time: 0 Render date: 2024-12-03T19:16:33.221Z Has data issue: false hasContentIssue false
  • English
  • Français

Field and biostratigraphic evidence for an unconformity at the base of the Eycott Volcanic Group in the English Lake District

Published online by Cambridge University Press:  01 May 2009

David Millward  and
Stewart G. Molyneux
David Millward
Affiliation:
British Geological Survey, Windsor Court, Windsor Terrace, Newcastle upon Tyne NE2 4HB, U.K.
Stewart G. Molyneux
Affiliation:
British Geological Survey, Keyworth, Nottingham NG12 5GG, U.K.
Get access Rights & Permissions [Opens in a new window]

Abstract

The Eycott Volcanic Group of the Lake District Lower Palaeozoic inlier consists of basaltic and andesite and and andesite sheets and associated, mainly coarse, volcaniclastic rocks. The volcanic rocks have been regarded previously as interdigitated with, and equivalent in age to, mudrocks of the upper part of the Skiddaw Group (Tremadoc–Llanvirn). Microfloral evidence has been quoted in support of this interpretation, but has not been substantiated by re-assessment of the critical data. Furthermore, a recent examination of the base of the Eycott Volcanic Group has shown that it rests with angular unconformity on the Skiddaw Group. Skiddaw Group rocks beneath the unconformity range in age from possible late Cambrian to early Llanvirn. The lowest part of the Eycott Volcanic Group, the Over Water Formation, consists of siltstones and tuffaceous sandstones yielding a diverse microflora, and is intercalated with two andesite sheets interpreted herein as sills. Since the currently accepted Llanvirn age for the Eycott Volcanic Group cannot be confirmed, the volcanism may have been penecontemporaneous with the Llandeilo–Caradoc Borrowdale Volcanic Group episode. There are implications for a pre-volcanic tectonic deformation episode.

Type
Articles
Information
Geological Magazine , Volume 129 , Issue 1 , January 1992 , pp. 77 - 92
Copyright
Copyright © Cambridge University Press 1992

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Allen, P. M. & Cooper, D. C. 1986. The stratigraphy and composition of the Latterbarrow and Redmain sandstones, Lake District, England. Geological Journal 21, 59–76.CrossRefGoogle Scholar
Arthurton, R. S. & Wadge, A. J. 1981. Geology of the Country around Penrith. Memoir, Geological Survey of Great Britain, England & Wales Sheet 24, 177 pp.Google Scholar
Branney, M. J. 1988. The subaerial setting of the Ordovician Borrowdale Volcanic Group, English Lake District. Journal of the Geological Society, London 145, 887–90.CrossRefGoogle Scholar
Branney, M. J. & Suthren, R. J. 1988. High-level peperitic sills in the English Lake District: distinction from block lavas, and implications for Borrowdale Volcanic Group stratigraphy. Geological Journal 23, 171–87.CrossRefGoogle Scholar
Burmann, G. 1968. Diacrodien aus dem unteren Ordo-vizium. Paläontologische Abhandlungen, Abteilung B 2, 637–60.Google Scholar
Burmann, G. 1970. Weitere organische Mikrofossilien aus dem unteren Ordovizium. Paläontologische Abhandlungen, Abteilung B 3 (3–4), 289–332.Google Scholar
Colbath, G. K. 1979. Organic-walled microphytoplankton from the Eden Shale (Upper Ordovician), Indiana, USA. Palaeontographica, Abteilung B 171, 1–38.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.CrossRefGoogle Scholar
Cramer, F. H., Allam, B., Kanes, W. H. & Diez, M. del C. R. 1974. Upper Arenigian to lower Llanvirnian acritarchs from the subsurface of the Tadla Basin in Morocco. Palaeontographica Abteilung B 145, 182–90, pls 27–28.Google Scholar
Cramer, F. H. & Diez, M. del C. R. 1977. Late Arenigian (Ordovician) acritarchs from Cis-Saharan Morocco. Micropaleontology 23, 339–60.CrossRefGoogle Scholar
Cramer, F. H., Kanes, W. H., Diez, M. del C. R. & Christopher, R. A. 1974. Early Ordovician acritarchs from the Tadla Basin of Morocco. Palaeontographica Abteilung B 146, 57–64.Google Scholar
Dean, W. T. & Martin, F. 1978. Lower Ordovician acritarchs and trilobites from Bell Island, Eastern Newfoundland. Bulletin of the Geological Survey of Canada no. 284, 35 pp.CrossRefGoogle Scholar
Deunff, J. 1954. Veryhachium, genre nouveau d'Hystrichosphères du Primaire. Compte rendu sommaire des séances de la Société géologique de France 13, 305–7.Google Scholar
Deunff, J. 1959. Microorganismes planctoniques du Primaire armoricain. I. Ordovicien du Veryhac'h (Presqu'île de Crozon). Bulletin de la Société géologique et minéralogique de Bretagne (nouvelle série), for 1958, (2), 1–41.Google Scholar
Deunff, J. 1964. Systématique du microplancton fossile à Acritarches. Révision de deux genres de l'Ordovicien inférieur. Revue de Micropaléontologie 7, 119–124.Google Scholar
Deunff, J., Górka, H. & Rauscher, R. 1974. Observations nouvelles et précisions sur les Acritarches à large ouverture polaire du Paléozoïque inférieur. Geobios 7, 5–18.CrossRefGoogle Scholar
Downie, C. 1959. Hystrichospheres from the Silurian Wenlock Shale of England. Palaeontology 2, 56–71.Google Scholar
Downie, C. 1984. Acritarchs in British stratigraphy. Geological Society of London Special Report no 17.Google Scholar
Downie, C. & Soper, N. J. 1972. Age of the Eycott Volcanic Group and its conformable relationship to the Skiddaw Slates in the English Lake District. Geological Magazine 109, 259–68.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 Britain, England & Wales Sheet 23.Google Scholar
Edwards, D. & Burgess, N. D. 1990. Plants. In Paleobiology – a Synthesis (eds Briggs, D. E. G. and Crowther, P. R.), pp. 60–4. Oxford: Blackwells Scientific Publishers.Google Scholar
Eisenack, A. 1965. Die Mikrofauna der Ostseekalke. 1. Chitinozoen, Hystrichosphären. Neues Jahrbuch für Geologie und Paläontologie Abhandlungen 123, 115–48.Google Scholar
Eisenack, A., Cramer, F. H. & Diez, M. Del C. R. 1976. Katalog der fossilen Dinoflagellaten, Hystrichosphären und verwandten Mikrofossilien. Band IV, Acritarcha, 2, Teil. Stuttgart: E. Schweizerbart'sche Verlagsbuchhandlung.Google Scholar
Fitton, J. G. & Hughes, D. J. 1970. Volcanism and Plate Tectonics in the British Ordovician. Earth and Planetary Science Letters 8, 223–8.CrossRefGoogle Scholar
Fortey, R. A., Beckly, A. J. & Rushton, A. W. A. 1990. International correlation of the base of the Llanvirn Series, Ordovician System. Newsletters on Stratigraphy 22, 119–42.CrossRefGoogle Scholar
Gray, J., Massa, D. & Boucot, A. J. 1982. Caradocian land plant microfossils from Libya. Geology 10, 197–201.2.0.CO;2>CrossRefGoogle Scholar
Green, J. F. N. 1917. The age of the chief intrusions of the Lake District. Proceedings of the Geologists' Association 28, 1–30.CrossRefGoogle Scholar
Ingham, J. K., McNamara, K. J. & Rickards, R. B. 1978. The Upper Ordovician and Silurian Rocks. In Geology of the Lake District (ed. F., Moseley), pp. 121–45. Yorkshire Geological Society, Occasional publication No. 3.Google Scholar
Jardiné, S., Combaz, A., Magloire, L., Peniguel, G. & Vachey, G. 1974. Distribution stratigraphique des Acritarches dans le Paléozoïque du Sahara Algérien. Review of Palaeobotany and Palynology 18, 99–129.CrossRefGoogle Scholar
Kjellström, G. 1971. Ordovician Microplankton (Balti-sphaerids) from the Grotlingbo Borehole No. 1 in Gotland, Sweden. Sveriges Geologiska Undersökning Series C no. 655.Google Scholar
Konzalová-Mazancová, M. 1969. Acritarcha Evitt 1963 aus dem Unter-Ashgil Böhmens. Palaeontographica Abteilung B 125, 81–92.Google Scholar
Loeblich, A. R. & Tappan, H. 1969. Acritarch excystment and surface ultrastructure with descriptions of some Ordovician taxa. Revista Española de Micropaleon-tologia 1, 45–57.Google Scholar
Martin, F. 1969. Les acritarches de l'Ordovicien et du Silurien belges. Détermination et valeur stratigraphique. Mémoires de l'Institut Royal des Sciences naturelles de Belgique 160, 1–75.Google Scholar
Martin, F. 1982. Some aspects of late Cambrian and early Ordovician acritarchs. In The Cambrian-Ordovician Boundary: Sections, Fossil Distributions, and Correlations (eds Bassett, M. G. and Dean, W. T.), pp. 29–40. National Museum of Wales, Geological Series No 3.Google Scholar
Martin, F. & Dean, W. T. 1981. Middle and Upper Cambrian and Lower Ordovician Acritarchs from Random Island, Eastern Newfoundland. Bulletin of the Geological Survey of Canada no. 343, 43 pp.Google Scholar
Martin, F. & Dean, W. T. 1988. Middle and Upper Cambrian Acritarch and Trilobite Zonation at Manuels River and Random Island, Eastern Newfoundland. Bulletin of the Geological Survey of Canada no. 381, 91 pp.CrossRefGoogle Scholar
Millward, D., Moseley, F. & Soper, N.J. 1978. The Eycott and Borrowdale Volcanic Rocks. In Geology of the Lake District (ed. F., Moseley), pp. 99–120. Yorkshire Geological Society, Occasional publication No. 3.Google Scholar
Molyneux, S. G. 1987. The Arenig Series in South Wales: stratigraphy and palaeontology. II. Appendix. Acritarchs and Chitinozoa from the Arenig Series of Southwest Wales. Bulletin of the British Museum of Natural History (Geology) 41, 309–64.Google 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. 1990. Advances and problems in Ordovician palynology of England and Wales. Journal of the Geological Society, London 147, 615–18.CrossRefGoogle 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, Edinburgh: Earth Sciences 79, 43–69.Google Scholar
Moseley, F. 1975. Structural relations between the Skiddaw Slates and the Borrowdale Volcanics. Proceedings of the Cumberland Geological Society 3, 127–45.Google Scholar
Moseley, F. & Millward, D. 1982. Ordovician volcanicity in the English Lake District. In Igneous Rocks of the British Isles (ed. Sutherland, D. S.) pp. 93–111. London: Wiley.Google Scholar
Rasul, S. M. 1976. New species of the genus Vulcanisphaera (Acritarcha) from the Tremadocian of England. Micropaleontology 22, 479–84.CrossRefGoogle Scholar
Rasul, S. M. 1979. Acritarch zonation of the Tremadoc Series of the Shineton Shales, Wrekin, Shropshire, England. Palynology 3, 53–72.CrossRefGoogle Scholar
Richardson, J. B. 1985. Lower Palaeozoic sporomorphs: their stratigraphical distribution and possible affinities. Philosophical Transactions of the Royal Society of London, B 309, 201–5.Google Scholar
Richardson, J. B. 1989. Late Ordovician and Early Silurian cryptospores and miospores from northeast Libya. In Subsurface Palynostratigraphy of Northeast Libya (eds A., El-Arnauti, B., Owens and B., Thusu), pp. 89–109. Garyounis University, Benghazi, Libya.Google Scholar
Rundle, C. C. 1979. Ordovician intrusions in the English Lake District. Journal of the Geological Society, London 136, 29–38.CrossRefGoogle Scholar
Rushton, A. W. A. & Molyneux, S. G. 1989. The bio-stratigraphic age of the Ordovician Skiddaw Group in the Black Combe Inlier, English Lake District. Proceedings of the Yorkshire Geological Society 47, 267–76.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 46, 175–92.CrossRefGoogle Scholar
Timofeev, B. V. 1959. Drevneyshaya flora Pribaltiki i ee stratigraficheskoe znachenie. Trudy vsesoyuznogo neftyanogo nauchno-issledovate'skogo geologo-razve-dochnogo Instituta 129, 1–319Google Scholar
Turner, R. E. 1984. Acritarchs from the type area of the Ordovician Caradoc Series, Shropshire, England. Palaeontographica Abteilung B 190, 87–157, plates 1–15.Google Scholar
Vavrdová, M. 1972. Acritarchs from Klabava Shales (Arenig). Věstník Ústředního ústavu geologického 47, 79–86.Google Scholar
Wadge, A. J. 1972. Sections through the Skiddaw–Borrowdale unconformity in eastern Lakeland. Proceedings of the Yorkshire Geological Society 39, 179–98.CrossRefGoogle Scholar
Wadge, A. J. 1978. Classification and stratigraphical relationships of the Lower Ordovician Rocks. In The Geology of the Lake District (ed. F., Moseley), pp. 68–78. Yorkshire Geological Society, Occasional Publication No. 3.Google Scholar
Wadge, A. J., Nutt, M. J. C., Lister, T. R. & Skevington, D. 1969. A probable Didymograptus murchisoni zone fauna from the Lake District. Geological Magazine 106, 595–8.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), NW England. Journal of Structural Geology 10, 463–72.CrossRefGoogle Scholar