Hostname: page-component-6bf8c574d5-h6jzd Total loading time: 0.001 Render date: 2025-02-20T15:03:47.965Z Has data issue: false hasContentIssue false
  • English
  • Français

The significance of large-scale sedimentary structures in the Silurian succession of western Ireland

Published online by Cambridge University Press:  01 May 2009

D. Michael Williams  and
T. Nealon
D. Michael Williams
Affiliation:
Geology Department, University College, Galway, Ireland
T. Nealon
Affiliation:
Geology Department, University College, Galway, Ireland
Get access Rights & Permissions [Opens in a new window]

Abstract

Large-scale sedimentary structures are described from the Lough Muck Formation (Wenlock) of north Galway, Ireland. They consist of bed packages separated by truncation surfaces of varying orientations. They had previously been interpreted as rotational slumps generated on a shelf–slope interface. It is shown that the structures formed in a tidally influenced environment far removed from a slope. They bear strong similarities to structures described from other tidal channel environments and it is proposed that they represent deposition on aggradational margins of such channels. The supposed slope–shelf transition is therefore not present at this level in the Silurian succession and much of the Lough Muck Formation may be of a dominantly shallow-marine origin.

Type
Articles
Information
Geological Magazine , Volume 124 , Issue 4 , July 1987 , pp. 361 - 366
Copyright
Copyright © Cambridge University Press 1987

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, J. R. L. 1981. Lower Cretaceous tides revealed by cross-bedding with mud drapes. Nature 289, 579–81.CrossRefGoogle Scholar
Attewell, P. B. & Farmer, I. W. 1976. Principles of Engineering Geology. London: Chapman & Hall.Google Scholar
Banks, N. L. 1973. Innerelv Member: Late Precambrian marine shelf deposit, east Finnmark. Norges geologiske undersokelse 288, 7–25.Google Scholar
Clifton, H. E. 1983. Discrimination between subtidal and intertidal facies in Pleistocene deposits, Willapa Bay, Washington. Journal of Sedimentary Petrology 53, 353–69.Google Scholar
Collinson, J. D. & Thomson, D. B. 1982. Sedimentary Structures. London: George Allen & Unwin.Google Scholar
Cotter, E. 1985. Gravel-topped offshore bar sequences in the Lower Carboniferous of southern Ireland. Sedimentology 32, 195–214.CrossRefGoogle Scholar
De Mowbray, T. & Visser, M. J. 1984. Reactivation surfaces in subtidal channel deposits, Oosterschelde, southwest Netherlands. Journal of Sedimentary Petrology 54, 811–24.Google Scholar
Galloway, W. E. & Hobday, D. K. 1983. Terrigenous Clastic Depositional Systems. New York: Springer-Verlag.CrossRefGoogle Scholar
Gill, W. D. 1979. Syndepositional sliding and slumping in the west Clare Namurian basin, Ireland. Special Paper No. 4. Geological Survey of Ireland.Google Scholar
Jackson, M. P. A. & Hobday, D. K. 1980. Gravity sliding and clay diapirism in a Pleistocene shoreline sequence in Zululand, South Africa. American Journal of Science 280, 333–62.CrossRefGoogle Scholar
Johnson, H. D. 1977. Shallow marine sand bar sequences: an example from the late Precambrian of north Norway. Sedimentology 24, 245–70.CrossRefGoogle Scholar
Kreisa, R. D. & Moiola, R. J. 1986. Sigmoidal tidal bundles and other tide-generated sedimentary structures of the Curtis Formation, Utah. Geological Society of America Bulletin 97, 381–7.Google Scholar
Laird, M. G. 1968. Rotational slumps and slump scars in Silurian rocks, western Ireland. Sedimentology 10, 111–20.CrossRefGoogle Scholar
Laird, M. G. & Mckerrow, W. S. 1970. The Wenlock sediments of north-west Galway, Ireland. Geological Magazine 107, 297–317.CrossRefGoogle Scholar
Mckerrow, W. S. 1979. Ordovician and Silurian changes in sea level. Journal of the Geological Society of London 136, 137–45.CrossRefGoogle Scholar
Piper, D. J. W. 1970. A Silurian deep sea fan deposit in western Ireland and its bearing on the nature of turbidity currents. Journal of Geology 78, 509–22.Google Scholar
Piper, D. J. W. 1972. Sedimentary environments and palaeogeography of the late Llandovery and earliest Wenlock of north Connemara, Ireland. Journal of the Geological Society of London 128, 33–51.CrossRefGoogle Scholar
Reineck, H. E. & Singh, I. B. 1973. Depositional Sedimentary Environments. New York: Springer-Verlag.CrossRefGoogle Scholar
Siegenthaler, C. 1982. Tidal cross-strata and the sediment transport rate problem: a geologist's approach. Marine Geology 45, 227–40.Google Scholar