Chemostratigraphy and stratigraphic distribution of keeled planktonic foraminifera in the cenomanian of the North German basin

Abstract

The record of keeled planktonic foraminifera during the Cenomanian in boreal epicontinental basins is discon-tinuous. Micropalaeontologic and bulk carbonate carbon and oxygen isotope investigations from two cores in the centre of the North German Basin (NGB, Wunstorf, Lower Saxony) showed keeled praeglobotruncanids and rotaliporids to exclu-sively appear during three stratigraphic intervals of varying duration in the lower and middle Cenomanian. Our new high-resolution carbon isotope (δ13Ccarb) composite curve shows that keeled foraminifera are absent during the Mid-Cenomanian Event (MCE) I. In the aftermath of MCE I, keeled planktonic foraminifera are present throughout. The data are correlated to previously published sequence stratigraphic models for the NGB. The presence/absence of keeled planktonic foraminifera in the epicontinental NGB is believed to be controlled by sea level and according environmental conditions in the epiconti-nental basin.