Redefining the Devonian–Carboniferous Boundary: An Overview of Problems and Possible Solutions

Abstract

The discussion regarding where the Devonian–Carboniferous boundary (DCB) should be placed has a long tradition. The current boundary criterion and the GSSP at La Serre have long been criticised, and research work during the last two decades has highlighted several problems. The discoveries of supposed Carboniferous taxa in Devonian strata (including the guide fossil) and taxonomic problems with the conodont lineage used to define the DCB have recently revived the discussion, not only about the suitability of the GSSP section, but also about the criterion itself. Several diverging approaches exist for the definition of the DCB, but none of them offers an easy solution. Future work must focus on detailed biostratigraphic work on different groups and should respect stratigraphic stability for the DCB. The profound changes in the latest Devonian–earliest Carboniferous biosphere culminated in the Hangenberg Event, evidence for which is found below (but not too far from) the DCB. It is easily recognizable in many sections without specific knowledge of the taxonomy of a specific fossil group. Hence, the Hangenberg interval offers an alternative for a reasonably accurate placement of the DCB, which is sufficient for many geologists, and the extinctions and appearances around the level offer great potential for detailed biostratigraphic zonations and thus for a precise definition of the DCB.