HOLIVAR2006 Abstracts
Palaeoenvironmental record from the southern Baltic Sea based on a high-resolution Optically Stimulated Luminescence (OSL) chronology.
Marloes Kortekaas1,2, Andrew S. Murray2 and Svante Björck1
1GeoBiosphere Science Centre, Quaternary Sciences, Lund University, Sölvegatan 12, SE-22362, Sweden
2Nordic Laboratory for Luminescence Dating, Department of Earth Sciences, Aarhus University, Risø National Laboratory, DK-4000 Roskilde, Denmark
Contact: Marloes Kortekaas (Marloes.Kortekaas@geol.lu.se)
The post-glacial history of the Baltic Sea is characterised by large water level and salinity changes related to opening and closing of the connections between the Baltic basin and North Atlantic. The shallow spill ways that connect the Baltic Sea to the North Atlantic imply that relatively small ocean variability can cause major changes in the circulation system within the Baltic basin. At present, westerly storms play a major role in pushing salt water from the North Atlantic into the Baltic basin.
Previous studies on palaeoenvironmental changes in the southern Baltic were mainly conducted in coastal settings with abundant organic material for 14C dating. Many of these records are, however, discontinuous due to the large water level fluctuations. In contrast, in the 45 m deep Arkona basin, the sediment record is thought to be continuous. Few studies have been carried out in this region, partly because low organic carbon content and the lack of macrofossils impeded the dating of these sediment records.
We report on investigations of a 10.86 m long sediment core from the centre of the Arkona basin covering the last 14 kyr. We have investigated palaeoenvironmental proxies for water level, salinity, and anoxia as indicators of the North Atlantic linkage. Chronological control is based mainly on Optically Stimulated Luminescence (OSL) ages. Internal tests of luminescence characteristics confirm the suitability of the material for OSL dating and the resulting OSL chronology compares satisfactorily with the more restricted set of radiocarbon ages on shells. Stratigraphic marker horizons have now been directly dated and this new chronology provides us new insights into the Holocene palaeoenvironmental changes in the Baltic Sea. We discuss the possible recording of the 8.2 kyr cold event in the Baltic basin.