New foraminifers in the Visean/Serpukhovian boundary interval of the Lower Limestone Formation, Midland Valley, Scotland

Abstract

The biostratigraphy of the upper part of the Mississippian Lower Limestone Formation in the Midland Valley, Scotland is revised using foraminiferal assemblages. This formation was previously assigned exclusively to the upper part of the Brigantian Substage (upper Cf6δ, P2 or latest Visean), whereas the succeeding Limestone Coal Formation (barren of foraminifers and conodonts) was assigned to the Pendleian Substage (lower Cf7, E1 or early Serpukhovian). The foraminifers, in particular those recorded from the Second Hosie and Top Hosie limestones and their lateral equivalents (Anvil and MacDonald limestones), are comparable to Serpukhovian assemblages from the Ukraine and Russia. Consequently, the Visean/Serpukhovian stage boundary is repositioned at the base of the Second Hosie Limestone. This assignment of the Second Hosie Limestone to the Pendleian is reinforced by the first occurrence of the ammonoid Emstites (Cravenoceras), although it occurs 1 m below the Top Hosie Limestone. Pendleian foraminiferal assemblages from northern England, its geographically closest equivalent, are similar but not well enough known for a detailed comparison. A few similarities are found between the foraminiferal assemblages from the Midland Valley and those from southwest Spain and North African basins. Faunas from the Second and Top Hosie limestones and their lateral equivalents allow us to propose an assemblage zone, valid for regional correlations within the British Isles, and the faunas can be potentially used as Serpukhovian markers for western Paleotethyan basins. Two new genera and species are described, Praeplectostaffella anvilensis n. gen. n. sp. and Praeostaffellina macdonaldensis n. gen. n. sp., and two new species, Tubispirodiscus hosiensis n. sp. and Euxinita pendleiensis n. sp.

Late Viséan–Serpukhovian foraminiferans and calcareous algae from the Adarouch region (central Morocco), North Africa

“…efremovi is a large species, and with better development of the pseudochomata than in Euxinita efremovi. It is rather similar to specimens recorded by the authors in the Pendleian (Early Serpukhovian) from the Midland Valley in Scotland (Cózar et al 2008). Both species attributed to 'Biseriella?'…”

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

“…A similar case is observed for Claracrusta and Fasciella crustosa, (Cózar, 2004;Cózar andSomerville, 2004, 2005;Cózar et al, 2008a;Vachard and Cózar, 2010).…”

Foraminiferal, calcareous algal and problematica assemblages from the Mississippian Lower Limestone Formation in the Midland Valley, Scotland

“…In the northern Pennines, eight calcareous microfossil assemblages were recognised for the stratigraphic interval spanning the late Asbian 'Basement Group' of the (Có zar et al 2008a), which allows the proposal of two new assemblages, Assemblages 9 and 10 (described below). Black areas represent non-depositional sequences, limestone names in grey areas represent the limestone horizons that were not sampled for this study.…”

“…Rare elements of these assemblages are: Climacammina sp., Endothyranopsis sphaerica ( Fig. 6e) [=Betpakodiscus, see taxonomic discussion in Có zar et al 2008a]. 6k), Tubispirodiscus and Draffania biloba, as well as the first occurrence of Miliolata foraminiferans, Calcivertella (Fig.…”

“…9b) are more common. 9f), denominated as Euxinita pendleiensis (in Có zar et al 2008a), together with Praeplectostaffella. Highlighted are Tubispirodiscus simplicissimus and Endostaffella shamordini (Fig.…”