Upper Cretaceous shallow-marine deposits of the southwestern Münsterland (northwest Germany) influenced by synsedimentary tectonics

During the Late Cretaceous global sea level rise, marine nearshore sedimentary rocks were deposited in the Münsterland (northwest Germany). Thirteen borehole cores recently drilled in the southwestern part of the Münsterland have supplied new data on the lithostratigraphy and facies patterns of these deposits. By combining biostratigraphy (planktonic/benthic foraminifera, calcareous nannofossils), gamma ray data and lithological observations from the drill cores and form auxilliary chipped drillings a detailed correlation scheme of the Cenomanian-Campanian succession has been established. The successions studied show considerable variations in thickness and lithology over an area of 850 square kilometres. The western part of the study area is dominated by a homogeneous sequence of glauconitic sandstones and marlstones (greensands). Eastwards, the lithology becomes more variable and marls predominate, particularly in Coniacian and lower-middle Santonian strata. The new findings allow for a revision of the current lithological scheme used for Upper Cretaceous deposits in the western part of northern Germany. A major result is the evidence for synsedimentary tectonics as a driving force for the formation of an intrabasinal structural high which has been derived from spatial facies and thickness patterns of lower Turonian deposits. The Late Cretaceous synsedimentary inversion tectonics is examined in two examples, yielding a maximum movement rate of 0.1 mm/year for the early Santonian. Local geological mapping activities within the study area have provided a stripped map of the Cretaceous cover and a base Cretaceous subsurface contour map.