Calcareous nannoplankton from the ‘Boreal’ Late Albian of NW Germany (Kirchrode I borehole): its biostratigraphy and cyclicity

One hundred and sixty samples from the continuously cored Kirchrode I research borehole were examined for calcareous nannoplankton. A total of 106 coccolith taxa were identified. The state of preservation varied from poor to good, mostly moderately good. The coccolith assemblages were assigned to the Eiffellithus turriseiffelii Zone (CC9) and Prediscosphaera columnata Zone (CC8) of the Upper Albian [Sissingh, Geol. en Mijnb., 56 (1977) 37]. A count of the taxa was made at 5 m intervals and in certain sections at 1 m intervals. tudy focuses on the dating of the sequence with calcareous nannofossils and the determination of the fluctuations in the abundance of calcareous nannofossils. The cyclicity found in the changes in their abundance was correlated with cycles determined for the changes in the calcium carbonate content of the sediment.