ORIGIN OF CHALK DEPOSIT IN THE DANISH BASIN: LATE CRETACEOUS FROM THE STEVNS-2 CORE.
Chalk is a marine fine-grained sediment formed by the accumulation of coccoliths, calcitic remains of microscopic phytoplanktonic algae. We present results on the main processes and settings leading to the deposition of the chalk in the Stevns-2 core, eastern Denmark. This core penetrated 350 m of upper Campanian–Maastrichtian sediments and was studied at a very high resolution of 1:10. Here we show how changes in the sedimentology of the chalk are influenced by global and regional mechanisms. The facies evolution shows short-term cyclic patterns. The short-term cyclic trends from fine to coarse grain are interpreted as finning-upward depositional sequences, and may be related to 4th and 5th order sea level changes. Long-term sequences match well paleotemperature changes as delineated in bulk oxygen isotopes. This is interpreted as the interplay between paleoclimatic and relative sea level changes. Superimposed to these changes, some particular wackestone facies can be defined by their high content in bioclastic laminae. These laminae are interpreted as lag deposits formed by strong bottom currents. These currents could be related either to storms or contour bottom currents, or both. The occurrence and frequency of those wackestone rich in lag deposits can thus reflect changes in the intensity of storms and/or contour bottom currents throughout the late Campanian–Maastrichtian.
Boussaha, M., University of Copenhagen, Denmark, email@example.com
Thibault, N. R., University of Copenhagen, Denmark, firstname.lastname@example.org
Stemmerik, L., Natural History Museum of Denmark, Denmark, email@example.com
Time: 16:00 - 18:00
Location: Poster/Exhibit Hall
Presentation is given by student: Yes