The influence of sea-level changes on Eocene coastal wetlands during greenhouse conditions at the southern edge of the proto-North Sea in Northern Germany

The sedimentary succession of the Helmstedt Lignite Mining District at Schöningen in northern Germany includes the upper Paleocene to lower Eocene Schöningen Formation and the middle Eocene Helmstedt Formation. It covers the entire Paleogene greenhouse phase including the long-term Early Eocene Climatic Optimum (EECO) and short-term events such as the Paleocene-Eocene Thermal Maximum (PETM/ETM1) and its gentle demise almost continuously in an estuarine situation at the southern edge of the proto-North Sea. Due to the interaction between changes in sea level, salt withdrawal in the subsurface and climate-related changes in runoff from the hinterland the area was subject to frequent changes between marine and terrestrial conditions, repeatedly leading to peat formation. A new robust stratigraphic framework for the succession is based on a combination of biostratigraphy, eustatic sea-level changes and carbon isotope data.

The more than 200 m thick succession with 13 up to 15 m thick lignites offers a rare opportunity to study Paleocene–Eocene near-coastal ecosystems and to trace the effects of long- and short-term climate change on the diversity and composition of the plant communities across 10 million years during the Paleogene greenhouse. As far as known, the estuarine succession at Schöningen is worldwide unique with respect to duration and continuity. The aim of an ongoing project is to study the response of the vegetation in this paralic environment to climate change by applying pollen and spores as proxies.