Assessing the palaeoceanographic and glaciological changes from the LGM to present in the Baltic Sea Basin and Baffin Bay, a multi-geochemical approach

Abstract

The application of multiple geochemical techniques provides a robust tool for analysis, especially in regard to the study of sediment cores affected by complicated provenance, oceanographic and glaciological dynamics over time.

A multi-geochemical approach utilising proxies such as osmium isotopes (187Os/188Os), biomarker, XRF, qXRD, REE, radiocarbon dating and sedimentological details was applied to sediment cores from Baffin Bay, the Baltic Sea and the Skagerrak. This approach was applied with the goal of further understanding the complicated ice sheet dynamics and palaeoceanographic changes since the Last Glacial Maximum around the core localities, and how these may have been influenced by changes in climate (e.g., the Younger Dryas), which has the potential to help provide context for future glaciological and oceanographical changes in response to climate shifts. The use of the 187Os/188Os system as a proxy for glaciological and changes in basin inflow/drainage was also further tested, being applied to cores in the Skagerrak and Baltic Sea for the first time.

Through using combinations of the geochemical techniques listed above, large scale changes in the Baltic Sea Basin’s history can be identified through the tracking of inflow and drainage events both inside and outside the basin. The first evidence in the central Skagerrak for the final drainage of the Baltic Ice Lake through south-central Sweden is found, and the transition of the freshwater Ancylus Lake into the brackish Littorina Sea stage are clearly depicted in the data from the central Baltic Sea. These techniques, however, are unable to differentiate the weak, short-lived marine incursions into the Baltic Basin during the Yoldia Sea stage from the varying influxes of freshwater due to melt of the Fennoscandian Ice Sheet. Further, in Baffin Bay, a radiogenic, felsic sediment source is recorded during the Baffin Bay Detrital Carbonate layers. The potential provenance of this is likely material transported by the Greenland Ice Sheet, although a Laurentide Ice Sheet source is not ruled out completely due to similar geologies between west Greenland and Baffin Island. Further, synchronous behaviour of ice sheets is recorded over BBDC1 coincident with the B lling-Aller d and Older Dryas, and asynchronous behaviour is recorded over BBDC0 coincident with the Younger Dryas showing a dynamic response from the ice sheets over both warmer and cooler climate periods.