EGU23-547
https://doi.org/10.5194/egusphere-egu23-547
EGU General Assembly 2023
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Climatic and environmental changes in the North Sea Basin during the Early Miocene 

Julie Margrethe Fredborg1,2, Ainara Sistiaga3, Emil Munck Soltau1, Karen Dybkjær2, Stefan Piasecki2, Erik Skovbjerg Rasmussen2, Nicolas Thibault1, and Kasia Kamilla Sliwinska2
Julie Margrethe Fredborg et al.
  • 1Department of Geoscience and Natural Resources Management (IGN), University of Copenhagen, Øster Voldgade 10, 1350 Copenhagen K, Denmark
  • 2Department of Geo-energy and Storage, Geological Survey of Denmark and Greenland (GEUS), Øster Voldgade 10, 1350 Copenhagen K, Denmark.
  • 3Globe institute, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K, Denmark

The Miocene Climatic Optimum (~17 to 14 Million years ago) has recently gained attention as a future climate analogue. However, the number of climatic records from the northern high and middle latitudes is very limited, so the global impact across this climatic transition is still poorly understood. The most northernly located site penetrating a nearly complete Miocene succession is located in the eastern North Sea Basin (Sdr. Vium borehole, Denmark). This research provides a multi proxy investigation performed on the Lower Miocene part of the succession. The studied interval corresponds with the time leading up to the onset of the Miocene Climatic Optimum. 

A total of 44 samples have been studied for their relative abundances of major palynological groups (dinocysts, acritarchs, spores, non-saccate pollen, saccate pollen and freshwater algae) and for the dinocyst/pollen ratio. In addition, 11 selected palynological samples were studied for their content of  dinocyst and acritarch taxa (counting a minimum of 200 specimens per sample).

 77 samples constitute the basis of a HH-XRF based chemical analysis. Furthermore, the n-alkanes of 8 samples have been analysed in order to assess their potential within a paleoenvironmental context. 

This study provides an updated age model (derived from dinocysts) and sequence stratigraphy of the Burdigalian (Early Miocene) succession of the Sdr. Vium core. The studied interval belongs to the Sumatradinium hamulatum Zone, the Cordosphaeridium cantharellus Zone and the Exochosphaeridium insigne Zone.  

XRF analysis combined with palynology improved the existing sequence stratigraphical framework of the studied site. Furthermore, the low resolution record of the n-alkanes show a good correlation between high content of the C23-25 and position of sequence boundaries.  

The changes in the relative abundance of warm-water dinocysts as well as alkenone-derived sea surface temperature suggest a brief interval of colder sea surface conditions just prior to the onset of the Miocene Climatic Optimum.  

 

How to cite: Fredborg, J. M., Sistiaga, A., Soltau, E. M., Dybkjær, K., Piasecki, S., Rasmussen, E. S., Thibault, N., and Sliwinska, K. K.: Climatic and environmental changes in the North Sea Basin during the Early Miocene , EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-547, https://doi.org/10.5194/egusphere-egu23-547, 2023.