The transition from glacimarine to marine conditions during the last deglaciation in eastern Skagerrak

The paleoceanographic and paleoenvironmental evolution is described in the eastern Skagerrak. Separable stratigraphic units in seismic profiles and twelve piston cores document a changing balance between erosion and accumulation since the latest deglaciation. Sediment supply and water depth but also whether the water mass is stratified or not are the important parameters in the processes controlling the depositional environment. The cores can be divided into two main units: a lower, well consolidated and clay-rich glacimarine mud with low organic content, and a silty, sandy, marine mud with relatively high organic content. The boundary between these two main units consists of an erosional surface, overlain by a coarse-grained lag. The deposition of the lower glacimarine mud started directly after deglaciation, at about 18.0 kyr BP. A major change in the sedimentation conditions at about 9.0 kyr BP led to a change from depositional to erosional conditions. The erosion has presumably removed a great part of the earlier deposits, creating the erosional surface which is present in the entire study area. Several dated samples above and below the erosional surface indicate a hiatus of about 10 kyr. In the south, the conditions changed again at about 5.0 cal kyr BP, allowing accumulation of the marine mud, while in the northern part erosive conditions continue to prevail. In the northern part, the marine mud is only deposited in limited areas, preferably sheltered areas along the coast.