Late- and post-glacial depositional environments in the Norwegian Trench, northern North Sea

The late Weichselian sequence in the northern part of the Norwegian Trench is composed of eight units. The two lowermost units are massive, firm to stiff diamictons, interpreted to have been deposited beneath ice-streams that in all likelihood reached the shelf edge. They are overlain by glaciomarine and normal-marine sediments deposited after 15000BP. The first phase of glacial retreat from the Norwegian Trench (15000–14800 BP) was very rapid and left a thin layer of proximal sediments on top of the tills. This was followed by a period with lower accumulation rates (14800–13600 BP), probably as a result of rapid source retreat and cold meltwater inhibiting dropstone fall-out. The end of this interval marks the change from ice-stream calving in cold water to melting on land. According to lithologic and isotopic data, the maximum rate of Fennoscan-dian ice-sheet disintegration took place around 12500 BP. The water temperatures declined significantly and rates of sedimentation and ice-rafting fell in association with the Younger Dryas period. The final retreat of the ice began as early as 10 500 BP, and the transition to normal-marine sedimentation is reflected by precipitation of iron oxide followed by pyrite, reduced sedimentation rates, and a change from terrigenous to biogenic sedimentation.