Ice Sheet and Ocean Interactions, Margin of the East Greenland Ice Sheet (14 Ka to Present): Diatom Evidence

Abstract

Seven marine sediment cores were collected from the Kangerdlugssuaq Trough off the southeast coast of Greenland. The trough cuts across the continental shelf from the fjord mouth to the upper slope in Denmark Strait and provides a sedimentary environment sheltered from the East Greenland Current flowing along the shelf. The cores have been 14C dated (accelerator mass spectroscopy dates) and analyzed for diatom accumulation rates and changes in floral composition. It was found that the shelf probably was not glaciated by grounded ice but occupied by an ice shelf and/or permanent sea ice between 14,000 years B.P. and the present. Average retreat rates of glacial/permanent sea ice were circa 60 m/yr between circa 13,500 and 11,000 years B.P. The retreat rates increased to about 150 m/yr between 11,000 to 10,000 years B.P. The increase is unexpected because this correlates with Fairbanks' (1989) projected low glacial meltwater discharge for the same time which is coeval with the Younger Dryas. Several events of sea surface warming/cooling took place on the outer shelf from 12,000 to 9000 years B.P. followed by cooling to the present, with a possible warming between 3000–4000 years BP. On the inner shelf pulses of warm/cool surface water occurred from 9000 to 6000 years B.P., which was succeeded by surface water cooling until present.