Thickness, distribution and depositional environment of Holocene sediments in the Norwegian part of the Skagerrak

Abstract

A regional seismic reflector separating an uppermost low-reflectivity Holocene unit from an acoustically layered, Lake Weichselian, glaciomarine unit below has been mapped in the Norwegian Skagerrak between Langesund and Egersund. The thickest Holocene deposits occur in the eastern part of the Skagerrak, with a generally decreasing thickness westwards. In the central part of the Norwegian Trench east of Lista, the Holocene soft clay is 7.5-15 m thick, while further west is generally less than 7.5 m thick. On the northern slope of the trench, east of Mandal, the thickness varies between 15 m and 35 m. West of Mandal, on the northern slope, Holocene sediments occur only within local basins.