Occurrence and significance of Cenomanian belemnites in the lower Danubian Cretaceous Group (Bavaria, southern Germany)

Abstract

The belemnite records of the lower Danubian Cretaceous Group (DCG, northeastern Bavaria, southern Germany) are compiled, taxonomically described and placed within the new integrated stratigraphic framework of the group. Three specimens from the lower Regensburg Formation (Saal Member) south of Regensburg can be assigned to Neohibolites cf. ultimus (d’Orbigny) and are dated as late Early Cenomanian (Mantelliceras dixoni Zone). Eight specimens represent Praeactinocamax plenus (Blainville) and occur in an event (plenus Event) in the lower Eibrunn Formation (Regensburg area) or basal Regensburg Formation (Roding area in the Bodenwöhrer Senke). Biostratigraphy and carbon stable isotopes suggest that the belemnite horizon with P. plenus in the DCG has strictly the same chronostratigraphic position (mid-Late Cenomanian, middle Metoicoceras geslinianum Zone) as elsewhere in Central and NW Europe. The lithostratigraphic units of the lower Danubian Cretaceous Group (i.e., the Regensburg and Eibrunn formations), however, are characterized by a pronounced diachronism based on their time-transgressive (i.e., onlapping) deposition during the Cenomanian–Early Turonian transgression. The distribution of P. plenus around the Mid-European Island can be easily explained by migration around the positive area without the necessity of a marine strait across the Bohemian Massif.