Stratigraphy of benthic foraminifera in Lägerdorf/Holstein

Benthic foraminifera were investigated in the standard section for the white Chalk of NW Germany, Lägerdorf/Holstein, ranging from middle Coniacian to lower Maastrichtian. Several differences were found between observed stratigraphic ranges of index species and previous literature data. Consequently a new biozonation was established based on benthic foraminifera. Index species include classical marker species as well as species formerly classified as additional faunal elements. The new zonation combines 20 foraminifera-zones which are accurately related to the macrofossil faunal-zones and allows a better calibration of microfossil ranges. While many first and last appearance data of benthic index foraminifera are nearly isochronous within the NW German Basin or adjacent basins, some of the species are slightly time transgressive. To quantity the development and changes in foraminiferal faunal composition over the long time interval covered by the Lägerdorf-section, innovation-rates (new appearing species per million years) were calculated. Significant peaks with up to 25.5 new species per million years are observed in the lower part of the Upper-Santonian, in the uppermost Lower-Campanian and the uppermost Upper-Campanian. These peaks are coincident with the major regressions in the upper part of the Upper-Cretaceous. They also proof correlations to changes in the macrofossil assemblages. Reactions of benthic foraminifera in relation to sea level fluctuations are discussed.