Munster Basin Explained

Munster Basin
Period:Devonian
Type:Sedimentary basin
Prilithology:Old Red Sandstone[1]
Country:Ireland

The Munster Basin is a late Middle to Upper Devonian age extensional (rift) sedimentary basin in the south-west of Ireland.[2] [3] The basin fill comprises fluvial Old Red Sandstone (ORS) magnafacies[4] [5] [6] with minor silicic volcanic[7] and mafic sub-volcanic[8] centres. The depocentre of the basin is located between the MacGillycuddy's Reeks and the Kenmare River on the Iveragh peninsula where the succession is at least ca. 6 km thick.[5] The non-marine ORS is conformably succeeded by latest Devonian coastal plain and shallow marine clastic deposits (the Toe Head Sandstone and Old Head Sandstone Formations, and equivalents), followed by shallow to deeper marine Carboniferous sandstones, mudstones and limestones of the South Munster Basin.[9] During the Late Palaeozoic Variscan (or Hercynian) orogeny the deposits in the basin were subjected to compressional deformation that resulted in pressure solution cleavage formation, buckle folding and contractional faulting[10] [11] under very low-grade metamorphic conditions.[12]

The oldest deposits found in the Munster Basin belong to the Valentia Slate Formation from which a silicic air-fall tuff bed (the Keel-Enagh Tuff) was radiometrically dated as 384.9 ± 0.7 Ma, which can be linked to local miospore biostratigraphic records.[13] In combination, this corresponds to a late Givetian chronostratigraphic age on recent Devonian time scales.[14] The general Late Devonian age of the basin fill is also given by miospore[15] [16] and fish fossil records.[17]

Notes and References

  1. Book: Friend. P.F.. New Perspectives on the Old Red Sandstone. 2000. Geological Society of London. Bath. 978-1862390713. Williams. B.P.J..
  2. Capewell, J.G. (1965) The Old Red Sandstone of Slieve Mish, Co. Kerry. Proceedings of the Royal Irish Academy, 64B, 155-171.
  3. http://www.dcenr.gov.ie/Natural/Exploration+and+Mining+Division/Geology+and+Mineral+Potential/ Department of Communications, Energy and Natural Resources:Natural Resources - Geology and Mineral Potential
  4. Graham, J.R. (1983) Analysis of the Upper Devonian Munster Basin, an example of a fluvial distributary system. In: Collinson, J.D. & Lewin, J. (eds) Modern and Ancient Fluvial Systems. International Association of Sedimentologists, Special Publication, 6, 473-483.
  5. Williams, E.A., Bamford, M.L.F., Cooper, M.A., Edwards, H.E., Ford, M., Grant, G.G., MacCarthy, I.A.J., McAfee, A.M. & O'Sullivan, M.J. (1989) Tectonic controls and sedimentary response in the Devonian-Carboniferous Munster and South Munster Basins, south-west Ireland. In: Arthurton, R.S., Gutteridge, P. & Nolan, S.C. (eds) The Role of Tectonics in Devonian and Carboniferous Sedimentation in the British Isles. Occasional Publications of the Yorkshire Geological Society, 6, 123-141.
  6. MacCarthy, I.A.J. (1990) Alluvial sedimentation patterns in the Munster Basin, Ireland. Sedimentology, 37, 685-712.
  7. Avison, M. (1984) Contemporaneous faulting, and the eruption and preservation of the Lough Guitane Volcanic Complex, Co. Kerry. Journal of the Geological Society of London, 141, 501-510.
  8. Graham, J.R., Russell, K.J. & Stillman, C.J. (1995) Late Devonian magmatism in west Kerry and its relationship to the development of the Munster Basin. Irish Journal of Earth Sciences, 14, 7-23.
  9. MacCarthy, I.A.J. (1987) Transgressive facies in the South Munster Basin, Ireland. Sedimentology, 34, 389-422
  10. Cooper, M.A., Collins, D., Ford, M., Murphy, F.X. & Trayner, P.M. (1984) Structural style, shortening estimates and the thrust front of the Irish Variscides. In: Hutton, D.H.W. & Sanderson, D.J. (eds) Variscan Tectonics of the North Atlantic Region. Geological Society, London, Special Publication, 14, 167-175.
  11. Cooper, M.A., Collins, D., Ford, M., Murphy, F.X., Trayner, P.M. & O'Sullivan, M.J. (1986) Structural evolution of the Irish Variscides. Journal of the Geological Society, London, 143, 53-61.
  12. Blackmore, R. (1995) Low-grade metamorphism in the Upper Palaeozoic Munster Basin, southern Ireland. Irish Journal of Earth Sciences, 14, 115-133.
  13. Williams, E.A., Sergeev, S.A., Stössel, I., Ford, M. & Higgs, K.T. (2000) U-Pb zircon geochronology of silicic tuffs and chronostratigraphy of the earliest Old Red Sandstone in the Munster Basin. In: Friend, P.F. & Williams, B.P.J. (eds), New Perspectives on the Old Red Sandstone, Geological Society of London, Special Publication, 180
  14. Kaufmann, B. (2006) Calibrating the Devonian Time Scale: A synthesis of U–Pb ID–TIMS ages and conodont stratigraphy. Earth-Science Reviews, 76, 175-190.
  15. Higgs, K. & Russell, K.J. (1981) Upper Devonian microfloras from southeast Iveragh, County Kerry, Ireland. Geological Survey of Ireland Bulletin, 3, 17-50.
  16. Higgs, K.T., MacCarthy, I.A J. & O'Brien, M.M. (2000) A mid-Frasnian marine incursion into the southern part of the Munster Basin: evidence from the Foilcoagh Bay Beds, Sherkin Formation, south-west County Cork, Ireland. In: Friend, P.F. & Williams, B.P.J. (eds), New Perspectives on the Old Red Sandstone, Geological Society of London, Special Publication, 180.
  17. Russell, K. J. (1978) Vertebrate fossils from the Iveragh Peninsula and the age of the Old Red Sandstone. Journal of Earth Sciences, Royal Dublin Society, 1, 151-162.

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