Facies changes in the Upper Devonian and Lower Carboniferous of South Cork, Ireland - a reassessment

Abstract

The North Ringabella section, critical to an understanding of the sub-carbonate facies changes in south Co. Cork, is redescribed. Three successive formations are detailed: the alluvial West Cork Sandstone Fm. (800+ m), the shallow-marine Coomhola Fm. (96+ m) and the fault-based Kinsale Fm. (340+ m), here a pro-delta and shallow-marine sequence. This is overlain by the calcareous Courtmacsherry Fm. The Devonian/Carboniferous boundary occurs about the base of the Kinsale Fm. Comparison with adjacent sections reveals a complex transgressive-regressive interplay. Four cycles are recognised. The first, in the Late Devonian, was affected by differential subsidence and was initially localised. The second, at the base of the Carboniferous, abruptly cut across earlier deltaic depositional patterns. Further delta growth in the Cork Harbour area was terminated by the third transgression, while the fourth marked the end of deltaic activity and the formation of a low-energy platform area around Cork Harbour upon which carbonate reefs ('Carboniferous Limestone') were subsequently developed