Rugose coral associations from the late Visean (Carboniferous) of Ireland, Britain and SW Spain

摘要

Eight Upper Visean rugose coral associations (RCA 1-8) have been identified, involving 37 genera and 55 species /species groups, from Ireland, Britain and SW Spain. Three of the associations: Aulophyllum-Dibunophyllum (RCA 1), Siphonodendron-Diphyphyllum-Actinocyathus (RCA 4) and Koninckophyllum-Siphonodendron-Siphonophyllia (RCA 6) occur mostly in the Brigantian, and four: Palaeosmilia-Axophyllum-Clisiophyllum (RCA 2), Siphonodendron-Solenodendron (RCA 3), Dibunophyllum-Axophyllum-Siphonodendron (RCA 5) and Lithostrotion- Siphonodendron (RCA 7) are typical of the Asbian. RCA 8 (Cyathaxonia-Rylstonia-Rotiphyllum) is not biostratigraphically important, as it contains long-ranging genera. Three associations (RCA 1, 7, 8) have generally low diversity (2-3 genera); four (RCA 2, 3, 5 & 6) moderate diversity (4-5 genera); and only RCA 4 (particularly RCA 4B) has high diversity (6-11 genera). Four associations are dominated by colonial corals (RCA 3, 4, 6 & 7); RCA 7 has abundant cerioid Lithostrotion, the others are dominated by fasciculate Siphonodendron; RCA 3 and RCA 4 often form biostromes. Six of the associations are characteristic of shallow-water shelf environments (RCA 1, 2, 4, 5, 6 & 7), with RCA 7 characterised by an in situ wave-resistant coral framework (bioherm). RCA 3 is a deeper water shelf assemblage and RCA 8 is a mainly deeper slope/ramp association of solitary rugosans in a basinal setting, but also occurs rarely in shallow-water lagoons.