Irish Serpukhovian revisited

Abstract

In this study of Mississippian rocks in Ireland, it is now recognized, based on faunal evidence, that several upper Viséan limestone formations which were previously excluded from the Serpukhovian now belong, in part, to the lower two substages of the Serpukhovian. A reassessment of previous foraminiferal determinations, together with new foraminiferal data, has confirmed that rocks equivalent to the Tarusian and Steshevian substages are present in several sections. In the Slievenaglasha Formation and Magowna Formation (County Clare) and Deer Park Formation (County Meath), Tarusian and Steshevian foraminiferal assemblages are thus recorded. In the Clogrenan Formation (County Carlow), Carganamuck Limestone Formation (County Armagh) and Rockdale Limestone Formation (County Tyrone), Tarusian foraminiferal assemblages are recorded in the upper beds of thick limestone successions. Key foraminiferal and algal taxa characterize each assemblage, which have been correlated with equivalent Serpukhovian strata in the north of England and Scotland. A three‐stage evolution is recognized in archaediscid foraminifers: from Neoarchaediscus gregorii, followed by Neoarchaediscus postrugosus form 1, and N. postrugosus form 2, with Neoarchaediscus postrugosus form 1 used to define the base of the Serpukhovian. The recognition of Tarusian and Steshevian foraminiferal assemblages implies that areas of shallow‐water platform carbonate sedimentation in Ireland during the upper Viséan (Brigantian) persisted into the Early Serpukhovian.

A late Asbian (Mississippian) stratotype for England: Trowbarrow Quarry, Cumbria, UK

“…However, we suggest that Asteroarchaediscus first occurs in the Brigantian in Britain and Ireland (Fewtrell et al . 1981; Riley 1993; Cózar & Somerville 2021 a , 2021 b ), although the concept of Asteroarchaediscus for these authors is not exactly the same (see the discussion in Cózar & Somerville, 2020). Also, near the base of the Cf6γ2a assemblage occur rare ‘ Millerella ’ (Fig.…”

“…Foraminiferal assemblages are a continuation of the Humphrey Head Limestone Member, where there are some new occurrences of Neoarchaediscus species ( N. parvus , N. incertus ) (see the position of those species in the Janny Wood section in Cózar & Somerville 2021 a ) but with a predominance of large Archaediscus (Cózar & Somerville 2004). The best marker for the recognition of the Alston Formation in Trowbarrow Quarry is the problematic Algospongia Claracrusta catenoides (Homann, 1972) Vachard in Vachard & Montenant, 1981 (Fig.…”

Middle to Late Mississippian and Early Pennsylvanian foraminiferal zonal scheme of South China—a case study from the Youjiang Basin: biostratigraphical and palaeobiogeographical implications

“…The assemblage is correlated with the MFZ15 of Belgium due to the occurrence of Climacammina (Poty et al 2006), although the first Janischewskina is certainly older in China. In Britain and Ireland, Climacammina first occurs in the uppermost part of the lower Brigantian in the Assemblage 6 (upper), immediately below the Viséan-Serpukhovian boundary (Cózar & Somerville 2016, 2021a, 2021b. This Assemblage 6 corresponds to the level where the conodont Lochriea ziegleri has been recorded from Britain and Ireland (see Sevastopulo & Barham 2014;Barham et al 2015;Cózar & Somerville 2021a), although successions in Britain likely present the oldest appearance of this conodont (Cózar et al 2019;Nikolaeva et al 2020).…”

Foraminifers and conodonts in the Danlu section, South China: implications for the Viséan–Serpukhovian boundary (Mississippian)

“…5W, X). Brenckleina is notably recorded from the late Serpukhovian, but rarely, it has been reported from the upper part of the Steshevian (Poletaev et al 1991) or in intermediate positions of this substage from Tian Shan, England, Ireland and Spain (Kulagina et al 1992; Cózar & Somerville, 2014; 2016, 2021 b ; Cózar et al 2016). In contrast, E .…”

“…There, Neoarchaediscus postrugosus (Reitlinger) and other Tarusian foraminiferal markers have been found far below the Ardvarney Limestone Member, where the P2a subzone was located (Sevastopulo & Barham, 2014). According to the ammonoids, the FOD of L. ziegleri would correspond to the base of the Tarusian, whereas foraminifers suggest a Steshevian Substage (Cózar & Somerville, 2021 b ). At Kilnamona, by contrast, its FOD has been well constrained to levels of the E1a subzone, within the middle part of the Steshevian (Fig.…”