An evaluation of biostratigraphic markers across multiple geological sections in the search for the GSSP of the base of the Serpukhovian Stage (Mississippian)

Foraminiferal biostratigraphy of Brigantian-Arnsbergian limestones from eastern Scotland and Northumberland (northeast England)

“…However, foraminiferal assemblages from the Pendleian and Arnsbergian have never been defined. Indeed, some foraminifers present in this study show different stratigraphic ranges elsewhere in the Palaeotethys (e.g., Cózar et al 2019;Nikolaeva et al 2020), but their regional stratigraphic ranges in classical successions from England and Scotland seem to be a more appropriate approach for a detailed bed-by-bed correlation. Due to the different status of the carbonate units in the siliciclastic-dominant upper Viséan and Namurian cyclothemic successions, all the limestone beds formally defined as members within Alston and Stainmore formations (Northumberland) will be considered herein as 'limestone', to avoid any potential confusion in lithostratigraphic nomenclature.…”

“…In South Northumberland, new occurrences include Archaediscus at tenuis stage, which likely first occurs from the Four Fathom Limestone or Three Yard Limestone. Also present are Janischewskina delicata (Malakhova) and Janischewskina gibshmanae Cózar, Somerville, Sanz-López & Blanco-Ferrera, which previously had only been recorded in Britain from the Lower Felltop Limestone, much later that in most European basins (e.g., Gibshman 2003;Cózar et al 2019;Gibshman et al 2020;Nikolaeva et al 2020).…”

Irish Serpukhovian revisited

“…In several sections, notably the Clogrenan Formation, a succession of distinct evolutionary events can be recognized, with the FAD of N. gregorii , followed by N. postrugosus form 1, and N. postrugosus form 2. In Russia N. postrugosus is currently used as the marker taxon to define the base of the Serpukhovian (Gibshman, 2003; Kulagina, Stepanova, Kucheva, & Nikolaeva, 2011; Nikolaeva et al, 2020). What is particularly unique about most of the upper Viséan‐Serpukhovian successions in Ireland (except Cuilcagh Mountains and Ballycastle), is that they are represented by thick continuous limestone units, unlike most other coeval successions in northern Europe which are cyclothemic, with thin limestone beds alternating with thick clastic units, for example, Moscow Basin, Urals, Ukraine, Poland, northern England, and Scotland.…”

“…This implies that the base of the Serpukhovian should be relocated in slightly older levels, within the upper Viséan, than in the former parastratotype of the Serpukhovian in the Zabori'e Quarry of the Moscow Basin (Gibshman, 2003; Skompski et al, 1995). In the last few years, numerous publications have been dedicated to the search for Lochriea ziegleri around the world (see references in Cózar, Vachard, Aretz, & Somerville, 2019; Nikolaeva et al, 2020). However, the supposed synchronous first occurrence of this taxon is still a matter of discussion (e.g., Barham, Murray, Sevastopulo, & Williams, 2015; Cózar et al, 2019; Herbig, 2017; Nikolaeva et al, 2020; Sevastopulo & Barham, 2014).…”

“…In the last few years, numerous publications have been dedicated to the search for Lochriea ziegleri around the world (see references in Cózar, Vachard, Aretz, & Somerville, 2019; Nikolaeva et al, 2020). However, the supposed synchronous first occurrence of this taxon is still a matter of discussion (e.g., Barham, Murray, Sevastopulo, & Williams, 2015; Cózar et al, 2019; Herbig, 2017; Nikolaeva et al, 2020; Sevastopulo & Barham, 2014). A significant problem which complicates the study of the first appearance datum (FAD) of this taxon, is the lack of calibration in the international correlations of biozones and regional stages (now recognized as regional substages), used in many countries/basins, compared to the standard chronostratigraphic scale (see Davydov, Korn, Schmitz, Gradstein, & Hammer, 2012).…”