The core section of HG 7025 Struppen-Siedlung: a new standard section for the facies transition zone of the Saxonian Cretaceous Basin (Lower Cenomanian–Upper Turonian, eastern Germany)

The sequence stratigraphic and facies analyses of the Lower Cenomanian to Upper Turonian core section HG 7025 provide a new standard section of the regional facies development and stratigraphic architecture in the so-called “Faziesübergangszone” (facies transition zone) of the Saxonian Cretaceous Basin. The section covers eight depositional sequences, divided by nine sequence-bounding sedimentary unconformities (SBs). The Lower Cenomanian depositional sequences DS Ce 1+2 and DS Ce 3 comprise the lower and upper fluvial Niederschöna Formation, separated by sequence boundary SB Ce 2. Above SB Ce 3, the Middle Cenomanian Wurmsandstein (DS Ce 4) displays the first marine influence in the succession. Intensifying this trend, the marine onlap continues during the early Late Cenomanian DS Ce 5, almost completely levelling the pre-existing paleo-topography. DS Ce 5 ends at SB Ce 5, representing a subaerial unconformity. Cenomanian marine onlap is completed by the plenus transgression during DS Ce-Tu 1, culminating in the lowermost Turonian Lohmgrund Horizon. The transition from Lower to Middle Turonian is marked by the regionally correlatable Bielatal Horizon of the Schmilka Formation (SB Tu 1). Both early Middle Turonian DS Tu 2 and Middle to early Late Turonian DS Tu 3 are defined by rapid sea-level rises and subsequent pronounced progradation phases. Separated by a subaerial unconformity (SB Tu 3), DS Tu 4 comprises a trans-/regressive cycle capped by SB Tu 4, marked by a sharp grain-size increase at the base of Sandstein c3. The Late Turonian DS Tu 5 is only represented by lowstand and early transgressive deposits.