Chemostratigraphy of the lower Danubian Cretaceous Group (Cenomanian–lower Turonian, Bavaria, SE Germany)—A new carbon isotope reference curve and inter-basinal correlation

Abstract

Core section KB 06-2020, drilled north of Regensburg (SE Germany), covering the lower Danubian Cretaceous Group, has been logged in detail and sampled for chemostratigraphic investigation throughout the Cenomanian–lower Turonian. Resting unconformably on Upper Jurassic carbonates, the succession includes the Regensburg (lower Cenomanian–middle upper Cenomanian), the Eibrunn (Cenomanian–Turonian boundary interval), the Winzerberg (lower Turonian; Reinhausen and Knollensand members) and the Kagerhöh formations (middle Turonian, Eisbuckel and Pulverturm members only). The correlation of carbon stable-isotope trends from core section KB 06-2020 with the expanded Dover section (southern England) and the Bad Abbach section (south of Regensburg) provides evidence for a diachronous, NE-directed onlap of the Cretaceous strata onto the Bohemian Massif. Several Cenomanian carbon isotope events have been recognised (Mid-dixoni, P/B Break, Monument as well as the b1 and b2 peaks) while the selective absence of events above conspicuous sedimentary unconformities provides evidence for stratigraphic gaps associated with sea-level falls. A significant positive carbon isotope excursion in the Cenomanian–Turonian boundary interval, Oceanic Anoxic Event 2 (OAE 2), has been recorded in the Eibrunn Formation. Correlation with the European reference section from Eastbourne (southern England), Pont d'Issole (southern France), and the regional Grub section provides evidence of a rather complete development of OAE 2 in the Danubian Cretaceous Basin. The δ13C curve obtained from core section KB 06-2020 is proposed as a regional reference curve. Additionally, the Plenus Cold Event (PCE) is recognisable in the oxygen stable-isotope data.