Reappraisal of Arundian–Asbian successions of the Great Scar Limestone Group across northern England

Abstract

The correlation of disparate mid- to late Visean platform carbonate successions of the Great Scar Limestone Group across northern England formerly relied heavily upon a coral and brachiopod biozonation scheme erected in the early twentieth century. This subsequently guided the development of a regional chronostratigraphic scheme some sixty years later that continues to be used to the present day, broadly coinciding with development of new lithostratigraphical nomenclatures, different for each distinct structural area. Correlation problems encountered within these lithostratigraphic units from study of their foraminiferal assemblages, as well as critical analysis of the stratotype sections for the Holkerian and Asbian substages, questions the veracity of the long-established coral and brachiopod biostratigraphy. This study appraises the lithostratigraphical and biostratigraphical relationships of late Arundian to late Asbian limestones across the Askrigg and Alston blocks, the Stainmore Trough and flanks of the Lake District Block. It considers the correlation and potential rationalization of lithostratigraphic units, comments on revisions to the definition of the Holkerian and Asbian substage stratotypes and the suitability of the various biostratigraphical guide fossils.