Sediment Cores from the Arctic and Subarctic Seas

Abstract

The cores from the Norwegian and Greenland seas demonstrate the essential similarity between depositional processes in those seas and in the Atlantic. As in the Atlantic, there is clear evidence of the importance of slumping and of turbidity currents in redistributing sediments and in modifying the depositional record during postglacial time. In contrast, sediment believed to have been deposited during the last ice age is predominantly of glacial marine facies. Spitsbergen and the general region of the Barents Sea are the most probable sources of the ice-rafted material. The fluctuations in numbers of tests of Globigerina pachyderma in cores from the Arctic Ocean indicate a climatically controlled variation in the thickness and continuity of the ice cover of the Arctic Ocean. From our study of coiling direction in Globigerina pachyderma we have found that a northward shift of the 7.2 C isotherm took place at the end of the last ice age, and that the isotherm has never extended into the Norwegian Sea during the last 70,000 years. The evidence in the cores indicates that the net movement of floating ice must have been from north to south in the eastern half of the Norwegian Sea, in contrast to the south-to-north current now flowing there. The evidence indicates that there was a confluence of ice drifting from the northeast and ice drifting from the southeast off the coast of Norway at about latitude 62[degree] N.