THE LATE QUATERNARY SEDIMENTARY RECORD IN SCORESBY SUND, EAST GREENLAND

Until recently, little was known about the Quaternary marine sedimenta ry record in East Greenland. Geophysical and geological investigations in Scoresby Sund were undertaken to characterize the nature and chron ology of this record. Seismic records show that almost 70% of the oute r fjord system is covered by about 10 m of unlithified sediments, maki ng direct correlation with the Quaternary records on land and the adja cent continental margin difficult. These acoustically unstratified sed iments are scoured by icebergs above 550 m water depth. Almost 90% of core material is massive diamicton of Holocene age, deposited mainly f rom iceberg rafting and turbid meltwater. Sedimentation rates are 0.1- 0.3 m 1000 yr(-1). Thicker accumulations of unlithified Quaternary sed iments in Scoresby Sund occur as sediment ridges and in two other majo r depocentres. A low sediment ridge runs across the mouth of Scoresby Sund, and is interpreted as an end moraine of Late Weichselian Flakker huk stadial age. The very restricted sediment thickness suggests that grounded ice filled the fjord during the Flakkerhuk and an ice shelf w as not present. High inputs of ice rafted debris to the continental ma rgin at about 18 000 BP indicate this as a probable age for the morain e. During the Allerod Interstadial, ice probably retreated from the ou ter fjord system, since massive diamictons similar to those of Holocen e age are present at the base of most cores. A major depocentre of aco ustically stratified sediments at the head of Hall Bredning is interpr eted to represent ice proximal deposits from a glacier margin extendin g across the fjord. It is adjacent to dated moraines on land and is in ferred to be of Milne Land stadial age (about 10 000 BP). A similar ag e is interpreted for acoustically laminated sediments and a moraine al the entrance of Vikingebugt, on the south side of Scoresby Sund. Date d kame terraces in the inner fjord system indicate that ice retreated to its present position 6-7000 years ago.