Foraminiferal biostratigraphy of the post-mid-Miocene in the Danish Central Trough, North Sea

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Abstract The formatiniferal content of ditch cutting samples from three exploration wells in the Danish North Sea has been investigated in the sections above the mid-Miocene marker. The wells are Cleo-1, situated at the edge of the Central Trough, and Kim-1 and M-10 situated in the central part of the trough, in the northern and the southern part, respectively. Based on analysis of the benthic foraminiferal faunas, the strata in the boreholes are subdivided in accordance with the standard North Sea zonation. The interpretations of the faunal assemblages indicate the oldest strata to be deposited in an open marine, outer shelf environment. Up-hole through the wells, the content of planktonic species diminishes gradually; the benthic assemblages indicate shallowing water depth reaching an inner shelf to littoral environment. This is interpreted to reflect the filling of the North Sea Basin through the Middle to Late Miocene when sedimentation mainly occurred in the north. In Early Pliocene the sedimentation centre had shifted to the south whereas in Late Pliocene a hiatus is found in the south and northeast and sedimentation only took place in the northwest in the basin centre. The faunas in the Pleistocene deposits indicate an inner shelf to littoral environment, with periods of reduced salinity and non-marine sedimentation.