Foraminifers in upper Viséan–lower Serpukhovian limestones (Mississippian) from South Wales: regional correlation and implications for British foraminiferal zonal schemes

Abstract

Foraminiferal assemblages have been recorded in sections from the Gower Peninsula and North Crop in South Wales, of Holkerian (Stormy Limestone Formation), late Asbian to lower late Brigantian (Oxwich Head Limestone Formation) and late Brigantian (Oystermouth Formation) age. The absence of lower Asbian foraminifers in the studied successions is confirmed. These formations and biostratigraphic boundaries are correlated with those in northern England, where similar foraminiferal assemblages are recorded. It is considered that Loeblichia paraammonoides does not occur in Wales. Its record is based on a misidentification of L . ammonoides and its presence in Britain is questioned. The distribution of Bibradya in Britain seems to be restricted to the late Asbian. Archaediscus at angulatus stage and ancestral forms of Palaeotextularia are confirmed in the uppermost Holkerian. Ancestral forms of Koskinobigenerina and Climacammina recorded below the upper Asbian and lower Brigantian, respectively, are considered to be misidentifications. Archaediscus at tenuis stage recorded from the Oystermouth Formation can form a plausible marker for the equivalent Three Yard Limestone and Four Fathom Limestone members in northern England. The acme of discoidal archaediscids is equivalent to the Four Fathom Limestone Member. In contrast to a ready comparison with foraminiferal microfaunas from northern England, comparison with North Wales is problematic. Nevertheless, it would appear that most assemblages previously cited as early Asbian, would now likely be reassigned to the late Asbian, similar to the observations in South Wales.