Inter-regional sequence-stratigraphical synthesis of the Plänerkalk, Elbtal and Danubian Cretaceous groups (Germany): Cenomanian–Turonian correlations around the Mid-European Island

Abstract

Sequence-stratigraphical case studies of lower Upper Cretaceous shelf successions deposited in the periphery of the Mid-European Island (MEI) have been undertaken to precisely date sedimentary unconformities and corresponding depositional sequences, to test their inter-regional correlation, and to relate the observed stratigraphical architectures to a tectonic or eustatic control. In total, ten 3rd-order sequence-bounding unconformities (SB) have been identified in Cenomanian–Turonian sections from the Münsterland (MCB), Lower Saxony (LSB), Saxonian (SCB) and Danubian Cretaceous basins (DCB). SB Ce 1–3 are of early, mid- and late early Cenomanian age, while SB Ce 4 has been recognized in the uppermost middle and SB Ce 5 in the mid-upper Cenomanian strata. SB Tu 1 has been placed in the early–middle Turonian boundary interval and SB Tu 2 is a mid-middle Turonian unconformity. Sequence boundaries SB Tu 3–5 are of earliest late, mid-late and latest Turonian age, respectively. These inter-regional unconformities define depositional sequences DS Ce 1–5, DS Ce–Tu 1 and DS Tu 2–4 that are stacked into a 2nd-order cycle with a major onlap phase during the Cenomanian and early Turonian, culminating in a late middle Turonian 2nd-order maximum flooding. SB Ce 3 and Ce 5 as well as SB Tu 2 and Tu 4 represent major unconformities associated with eurybatic sea-level falls and subsequent rises of significant amplitude based on their stratigraphical and sedimentological signatures. Plate margin deflection or plate buckling are rather unlikely causes of the inferred sea-level changes given the considerable distance (>500 km) between the investigated basins and the long-distance persistence of the unconformities in identical stratigraphical positions. Inversion tectonics, however, influenced sedimentation from the mid-Turonian, increasing subsidence of marginal troughs along basin-bounding future thrust faults. However, careful intra- and inter-basinal correlations allow recognition of these tectonic signals. The present sequence-stratigraphic synthesis is in good agreement with recently published Cretaceous eustatic charts and thus provides a strong case for the inter-regional nature of early Late Cretaceous unconformities and corresponding depositional sequences in Europe, supporting a predominant eustatic control on Cenomanian–Turonian sequence architectures.