Late Viséan buildups at Kingscourt, Ireland: possible precursors for Upper Carboniferous bioherms

Abstract

Two late Viséan (Asbian-early Brigantian) buildup complexes occur in the Kingscourt Outlier in Ireland, near the top of the Mullaghfin Formation, a shallow-water, grainstone unit. These massive buildups at Ardagh and Cregg accumulated on the margins of a carbonate platform bordering a deep-water basin. Both have a buildup facies of fine-grained, peloid-rich, algal lime mudstones and wackestones, interbedded with coarser grained intraclastic, skeletal packstones and grainstones (interbuildup facies). Microbial structures are well developed in the buildup facies, principally domal stromatolites, thrombolites and oncoidal fabrics of cyanophytes ( Ortonella and Girvanella ) with encrusting formainifers ( Aphralysia and Textrataxis ). Algal structures include rhodoliths ( Solenopora ) and fragments of Ungdarella and stacheiids, with less abundant chlorophytes ( Koninckopora ); in the interbuildup facies, Koninckopora is more abundant. Near the top of the Ardagh buildup is an unusual development of phylloid algal boundstone composed of the possible ancestral coralline red alga Archaeolithophyllum . This boundstone also contains encrusting bryozoans and foraminifers, and directly overlies abundant Brigantian in situ fasciculate rugose corals. This upper unit appears to be associated with a rapid shallowing event, which stimulated the development of a wave-resistant rigid framework. Laterally, bedded intraclastic skeletal packstones and grainstones, with thin interbedded clays and shales, pass into the lower part of the massive Ardagh buildup, but appear to onlap and drape the upper part of the buildup. Buildup clasts occur within the interbuildup facies and proximal flank facies, indicating synsedimentary cementation. Late Viséan buildups of the Ardagh type highlight an important period of diversification of colonial rugose corals and calcareous algae associated with the development of widespread shallow-water carbonate platforms worldwide. This allowed the emergence of new algal groups, particularly the red algae ( Archaeolithophyllum and Ungdarella ) and the palaeoberesellid green algae ( Kamaenella ), which subsequently dominated Upper Carboniferous wave-resistant bioherms.

Mississippian coral assemblages from the Khenifra area, Central Morocco: Biostratigraphy, biofacies, palaeoecology and palaeobiogeography

“…This is, however, a rich coral assemblage for microbial-mounds. It does have comparability to the Ardagh mound, Ireland, especially in the upper part of that mound (RCA6) where Brigantian colonial corals are abundant (Somerville et al, 1996;Somerville, 1997;Rodríguez and Somerville, 2007).…”

Mississippian (Early Carboniferous) stromatolite mounds in a fore-reef slope setting, Laibin, Guangxi, South China

“…It is only just after the beginning of the early Viséan stage that there was a resurgence of skeletal metazoan in the reef biome (Adams 1984;Dix and James 1987;Bancroft et al 1988;Webb 1989Webb , 1998Webb , 1999Webb , 2005Horbury 1992;Mundy 1994;Ahr and Stanton 1994). Mississippian carbonate buildups are known in eastern Australia (Jull 1968;Webb 1989Webb , 1998Webb , 1999Shen 2002;Shen andWebb 2005, 2008), western Newfoundland of Canada (Dix and James 1987), Europe (Adams 1984;Bancroft et al 1988;Horbury 1992;Lauwers 1992;Somerville et al 1992Somerville et al , 1996Somerville 2003;Pickard 1992Pickard , 1996Mundy 1994;Bridges et al 1995;Kirkham 2005;Aretz and Chevalier 2007), North Africa (Pareyn 1959;Bourque et al 1995;Madi et al 1996); northern Arkansas, New Mexico, Virginia and Texas of USA (Webb 1987;Ahr 1989;Christopher 1990;Ahr and Stanton 1994), Urals of Russia (Antoshkina 1998;Skompski et al 2001), and Japan (Ota 1968;…”

Pendleian (early Serpukhovian) marine carbonates from SW Spain: sedimentology, biostratigraphy and depositional model

“…Moreover, Archaeolithophyllum lamellosum Wray (Figure 9) is a typical Pennsylvanian species, but it occasionally occurs in the Serpukhovian in Poland (Skompski 1996), France (Vachard and Aretz in press) and Archaeolithophyllum sp. in the Brigantian of Ireland (Somerville et al 1996). The appearance of these foraminifera permits that the base of the San Antonio section be assigned to Zone 17 and the top to Zone 18.…”