I. D. Somerville, C. N. Waters, 2011. "Western Ireland", A Revised Correlation of Carboniferous Rocks in the British Isles, C. N. Waters, I. D. Somerville, N. S. Jones, C. J. Cleal, J. D. Collinson, R. A. Waters, B. M. Besly, M. T. Dean, M. H. Stephenson, J. R. Davies, E. C. Freshney, D. I. Jackson, W. I. Mitchell, J. H. Powell, W. J. Barclay, M. A. E. Browne, B. E. Leveridge, S. L. Long, D. McLean
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The Carboniferous rocks of western Ireland extend from the Ox Mountains in south Co. Mayo, south to Galway Bay, east to the western margin of the Dublin Basin Co. Roscommon (Chapter 21) and west to Clew Bay and Clare Island (Fig. 54). Tournaisian rocks of mostly continental or marginal marine facies, Visean rocks of mostly marine limestone, and Namurian predominantly marine and fluvio-deltaic siliciclastic rocks crop out in the region; the entire succession belongs to the Mississippian Subsystem. In western Ireland, late Tournaisian and Visean (Chadian-Asbian) aged shelf limestones occur within structurally-controlled basins, many of which are extensions of structures in the adjacent NW region (see Chapter 19). In the Castlebar area of south Co. Mayo, the Castlebar Syncline represents a SW extension of the Ballymote Syncline, bounded to the north by the Ox Mountains Inlier and to the south by the Belhavel Fault (Long et al. 2004).
Across most of the region the Tournaisian succession rests unconformably upon Devonian and older strata. However, in the east Galway area, the Tournaisian succession is thicker and contains more marine rocks representing an earlier arrival of the trangression from the south and rests conformably upon Devonian strata.