Palynology of the Dinantian Lower Border Group of the Solway Basin

Abstract

SUMMARY Miospore assemblages from the upper part of the Lower Border Group in Tarras Water, near Langholm, Dumfries and Galloway, are assigned to the Lycospora pusilla (Pu) Zone and the Knoxisporites triradiatus–K. stephanephorus (TS) Zone. Comparisons with similar assemblages from strata dated on their foraminiferal and/or conodont content suggest that the Tarras Water assemblages are early Visean, ranging from Chadian to Holkerian in age. Re-examined samples from the Bewcastle and Cambeck beds in the Bewcastle Anticline of Northumberland are assigned to the upper part of the Pu Zone and to the TS Zone respectively, suggesting that they are of Arundian and Holkerian age. Lycospores are more abundant in assemblages from the more marine Bewcastle sequence than in assemblages from Langholm sequence farther west. Such marked lateral changes of facies result in an eastward and northward reduction in numbers of stratigraphically useful fossils, creating uncertainty over dating and correlation of the Lower Border Group in this area. The present work suggests that the recently published correlations between sections in the Langholm–Newcastleton and Bewcastle areas may need to be revised. Several species that were not previously known from Britain or north-west Europe, but which may be of stratigraphical value, have been recorded. Two new species are described: Neoraistrickia variabilis sp. nov. and Schopfites claytonii sp. nov.