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.
The data for the paleoenvironmental study was obtained on the basis of complex analysis of short sediment cores retrieved in the Arcona, Bornholm, and Gdansk Basins of the Baltic Sea. The cores were collected using a short gravity sediment corer (Niemistö type). The upper layers (0-5 cm) of sediment cores were stained with the 80% ethanol solution of rose Bengal following the protocol (Schönfeld et al., 2012, doi:10.1016/j.marmicro.2012.06.001) and were used only for the microfossil analysis. The rests of the cores (below the 5 cm) were continuously sampled with the 1 cm step and were used for the loss on ignition (LOI), microfossil, X-ray fluorescence (XRF), and grain-size analyzes. For the micropaleontological analysis the samples were sieved through >63 μm mesh using tap water. Benthic foraminifera shells and inner organic linings were counted in a wet state following the (Brodniewicz, 1965; Binczewska et al., 2018, doi:10.1111/bor.12267).
Here, the Cd/Ca and Pb/Ca ratios in the two benthic foraminifera species Elphidium excavatum and Ammonia tepida are presented in order to assess the impact of enhanced anthropogenic heavy metal input in historical times on these foraminifera. The foraminifera shells were picked from sediment core GeoB 4801-1, that was collected from the Helgoland mud area, German Bight, southern North Sea, during RV Meteor cruise M40/0. The obtained elemental records span the last ~300 years (for the stratigraphy of this core see Boxberg et al. 2021, https://doi.org/10.1007/s00367-019-00592-0). Element compositions were obtained by ICP-MS at the MARUM, Bremen.