Integrated stratigraphy, facies patterns and palaeogeography of the lower Elbtal Group: a re-evaluation of the Cenomanian transgression in Saxony, Germany

Until very recently, it was generally assumed that the marine flooding of the Saxonian Cretaceous Basin (SCB) was largely related to the naviculare Transgression of the early Late Cenomanian. However, based on the detailed investigation of 39 Cenomanian sites at surface and subsurface, and considering new macrobiostratigraphic data and existing palynological facts, a completely revised integrated stratigraphic framework and palaeogeographic reconstructions of the lower Elbtal Group are presented (Niebuhr & Wilmsen 2023, ZDGG 174, DOI: 10.1127/zdgg/2023/0376). Demonstrably, Cretaceous sedimentation started already in the early Early Cenomanian, indicated by the contemporaneous onlap of non-marine (Niederschöna Formation) and marine strata (Oberhäslich Formation). The Cenomanian transgressions advanced from the north, at first following the course of roughly south–north-discharging palaeovalleys of a fluvial palaeodrainage system. Sequence stratigraphic analyses demonstrate the presence of four complete, unconformity-bounded Cenomanian depositional sequences (DS) and a fifth one, DS Ce-Tu 1, which started in the mid-Late Cenomanian and lasted into the Early Turonian. The depositional sequences comprise five major transgressive phases that overstepped each other, culminating in an earliest Turonian climax of the 2^nd-order Cenomanian transgressive hemicycle. The maximum thickness (100–120 m) equates to the accommodation generated by eustasy and regional subsidence during the entire 6-myr-long Cenomanian age (sedimentation rate ≤20 m/myr). Thickness changes within the lower Elbtal Group can quite simply be related to pre-transgression topography and sequence stratigraphic onlap patterns. Thus, the new stratigraphic and palaeogeographic framework of the lower Elbtal Group also demonstrates that tectonic inversion in the SCB was essentially a post-Cenomanian process.