Foraminifers of the Viséan–Serpukhovian boundary interval in Western Palaeotethys: a review

Abstract

A detailed revision of foraminiferal zonal schemes in sections throughout Europe and North Africa for the Viséan–Serpukhovian boundary interval suggests that several foraminiferal taxa might have the potential to form reliable markers throughout the Palaeotethys. This would support the currently investigated boundary definition based on the First Appearance Datum of the conodont Lochriea ziegleri. However, correlation of these foraminiferal markers in the Western Palaeotethys region has encountered several problems, partly arising from taxonomic issues, but mainly because of apparent discrepancies between the First Occurrence Data (FOD). Analysis of the available foraminiferal data has revealed that some taxa show marked delays in their FODs, due to the timing of westward dispersal within the Palaeotethys, emanating from a probable source in eastern Russia. As a result of this investigation, two dispersal routes have been identified, a northern branch and a southern branch. In general, the displacements within the southern branch occurred more rapidly than in the northern branch. In addition to different dispersal routes, separation of the main foraminiferal markers in stratigraphical sections from different regions can result from isolation of shallow‐water facies of the inner platform from those of relatively deeper‐water settings in the outer platform, the latter showing more consistent foraminiferal FODs. The differences in palaeobathymetry and associated energy levels have enabled two foraminiferal zonal schemes to be distinguished for the Viséan–Serpukhovian boundary interval in the Western Palaeotethys, one for the inner platform and a second one for the outer platform.

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.…”

“…The first occurrence of J. typica is also located in the Five Yard Limestone of northern England (Cózar & Somerville 2004). These are typical markers of the late Brigantian Assemblage 7 in Britain (Cózar et al 2008;Cózar & Somerville 2013, but also from the Serpukhovian in Western Europe (Cózar et al 2019). It is noteworthy for the occurrence of Praeostaffellina sp.…”

“…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).…”

“…7b, f, g, m). Most of these above-mentioned taxa were recorded in levels equivalent to the early Serpukhovian (e.g., Cózar et al 2019), and the occurrence of J. typica and Climacammina are more commonly recorded from the Five Yard Limestone, to which the Eelwell Limestone is correlated. This limestone contains the same foraminiferal Assemblage 7 as that of the Lower Skateraw (East Lothian), and St Monans Little/Charlestown Main limestones and Seafield Tower Limestone (East Fife) (Fig.…”

Irish Serpukhovian revisited

“…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).…”