Almost 90% of 39 m of core material recovered from Scoresby Sund and the adjacent East Greenland shelf is massive diamicton, interpreted to be formed predominantly by the release of iceberg rafted debris and reworking by iceberg scouring. There is also likely to be a contribution from suspension settling of fines derived from glaciofluvial sources. Model calculations suggest that the 14C derived Holocene sedimentation rate of 0.1‐0.3 m 1000 yr−1 in Scoresby Sund can be accounted for mainly by iceberg rafting of debris. A further 4% of core material is of gravel or coarse sand lenses, interpreted to reflect iceberg dumping of debris. Intensive iceberg scouring, which reworks sea floor sediments, is observed on acoustic records from over 30 000 km2 of the Scoresby Sund fiord system and the adjacent East Greenland shelf (69‐72°N and 75°N). The rate of iceberg production from Greenland Ice Sheet outlet glaciers, and iceberg drift tracks on the shelf, suggests that iceberg rafting and scouring may be important over a significant proportion of the 500 000 km2 area above the shelf break. The relatively extensive modern occurrence of massive diamicton, formed by iceberg rafting and scouring, together with suspension settling of fines, suggests that it may also be a significant facies in the glacier‐influenced geological record. The recognition in the geological record of the massive diamicton facies described above may also indicate the former presence of fast flowing ice sheet outlet glaciers.

No abstract

Until recently, little was known about the Quaternary marine sedimentary record in East Greenland. Geophysical and geological investigations in Scoresby Sund were undertaken to characterize the nature and chronology of this record. Seismic records show that almost 70% of the outer fjord system is covered by about 10 m of unlithified sediments, making direct correlation with the Quaternary records on land and the adjacent continental margin difficult. These acoustically unstratified sediments are scoured by icebergs above 550 m water depth. Almost 90% of core material is massive diamicton of Holocene age, deposited mainly from iceberg rafting and turbid meltwater. Sedimentation rates are 0.1 ‐0.3 m 1000 yr‐1. Thicker accumulations of unlithified Quaternary sediments in Scoresby Sund occur as sediment ridges and in two other major depocentres. A low sediment ridge runs across the mouth of Scoresby Sund, and is interpreted as an end moraine of Late Weichselian Flakkerhuk stadial age. The very restricted sediment thickness suggests that grounded ice filled the fjord during the Flakkerhuk and an ice shelf was not present. High inputs of ice rafted debris to the continental margin at about 18 000 BP indicate this as a probable age for the moraine. During the Allerød Interstadial, ice probably retreated from the outer fjord system, since massive diamictons similar to those of Holocene age are present at the base of most cores. A major depocentre of acoustically stratified sediments at the head of Hall Bredning is interpreted to represent ice proximal deposits from a glacier margin extending across the fjord. It is adjacent to dated moraines on land and is inferred to be of Milne Land stadial age (about 10 000 BP). A similar age is interpreted for acoustically laminated sediments and a moraine at the entrance of Vikingebugt, on the south side of Scoresby Sund. Dated kame terraces in the inner fjord system indicate that ice retreated to its present position 6–7000 years ago.

Abstraet Based on preliminary results of sedimentological and organic geochemical investigations, distinct changes in the composition of siliciclastic and biogenic components occured in sediments from the East Greenland Continental Slope and Shelf and Scoresby Sund during the latest Pleistocene to Holocene times. These changes probably reflect the (? early/) late Weichselian glacial to Holocene interglacial transition, i.e., the decay of continental iee masses and sea-ice cover, causing major changes in supply of terrigenous matter and surface-water productivity. Flux rates of coarse-grained ice-rafted debris (IRD) distinctly decreased on the continental slope/shelf during the deglaciation interval. During the last 10,000 years, major amounts of IRD were trapped in the Scoresby Sund system. In comparison to modern interglacial conditions, surface-water productivity was significantly lower during the last glacial.