Carboniferous, Northern Ireland

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Mitchell, W I (ed.). 2004. The geology of Northern Ireland-our natural foundation. Geological Survey of Northern Ireland, Belfast.

W I Mitchell

Introduction

Position of the continents in the early Carboniferous (c. 350Ma (1)) (P947814)
Position of the continents in the late Carboniferous (c. 300Ma (17)). (P947838)
Distribution and classification of Carboniferous rocks in Northern Ireland. (P947927)
Geological map of Northern Ireland showing the Carboniferous outcrop. (P947815)

At the end of the Devonian, Ireland lay on the southern margin of Laurentia that stretched from the Appalachians, northeast across Britain into Fennoscandia [1] (P947814). Coastal alluvial plains merged into shallow tropical waters at the edge of an inhospitable desert landscape. Although marine conditions had reached the southern tip of Ireland at the Devonian-Carboniferous boundary (c.355Ma) the succeeding 10Ma passed before the transgression reached the north of Ireland in the late Tournaisian [2]. This is only the first event in the turbulent 65Ma history of the Carboniferous in Northern Ireland (c.355–290Ma). Throughout the succession there is evidence of intermittent tectonic activity. Northern Ireland was not an area of quiet sedimentation, as previously envisaged, but straddled a zone of dextral strike-slip comparable to the Midland Valley of Scotland and the Maritimes Basin in Atlantic Canada [3]. Thus, by the end of the Carboniferous, when the Variscan Orogeny had reached a maximum intensity, all of Ireland was now land and the Variscan Mountains stretched across the northern part of the country (P947838).

Carboniferous rocks in Northern Ireland were deposited close to the northern margin of the "Northern Province" [4] and reflect the proximity of land at all times. Their cumulative thickness of 7000 m is represented mainly by Lower Carboniferous (Tournaisian, Viséan and early Namurian) rocks in Co. Fermanagh, the Fintona Block, peripheral sections at Coalisland and isolated basins such as Newtownstewart (P947927). The most continuous outcrop and succession extends from Co. Fermanagh and south Co. Tyrone into north Co. Armagh (P947815). The Carboniferous outcrop in the eastern part of Northern Ireland is reduced to outliers at Ballycastle, Cultra, Castle Espie and Carlingford Lough.

Litho- and biostratigraphy
Eastern Carboniferous outliers of Ballycastle, Cultra, Castle Espie and Carlingford
Ballycastle
Cultra
Castle Espie
Carlingford
Co. Londonderry
Fintona Block
Tempo-Lisbellaw Segment
Kilskeery Group (Table 7.5)
Milltown Segment
Greenan Sandstone Formation (Table 7.1)
Slievebane Group (Table 7.6)
Co. Armagh
Tyrone Group
Armagh Group
East Co. Tyrone
Tyrone Group (Table 7.7)
Armagh Group
Leitrim Group
Millstone Grit
Coal Measures
Newtownstewart Outlier
Co. Fermanagh-south Co. Tyrone
Derrygonnelly-Marble Arch-Cuilcagh Mountain
Tyrone Group
Leitrim Group
Lisnaskea
Tyrone Group
Leitrim Group
Fivemiletown-Clogher-Aughnacloy-Benburb
Fivemiletown-Clogher
Tyrone Group
Aughnacloy
Benburb
Kesh-Omagh
Omagh Sandstone Group
Tyrone Group
Palaeogeographical and environmental reconstruction
Late Courceyan (CM Biozone)
Chadian (Pu Biozone)
Arundian
Holkerian
Early Asbian
Late Asbian
Brigantian–Arnsbergian
Late Namurian-Westphalian A/B
Late Carboniferous-Early Permian

References

  1. Osborne, R, and Tarling, D H. 1995. The Historical Atlas of the Earth (A Visual Exploration of the Earth’s Physical Past). Viking. Penguin Books Ltd., London.
  2. Clayton, G, and Higgs, K. 1979. The Tournaisian marine transgression in Ireland. Journal of Earth Sciences of the Royal Dublin Society 2, 1–10.
  3. Calder, J H. 1998. The Carboniferous evolution of Nova Scotia. In: Blundell, D J, and Scott, A C. (eds.). Lyell: the Past is the Key to the Present. Publication of the Geological Society, London, No. 143, 261–302.
  4. Sevastopulo, G D, and Wyse Jackson, P N. 2001. Carboniferous (Dinantian). In: Holland, C. H. (ed.). The Geology of Ireland. Dunedin Academic Press, Edinburgh.