HISTORY OF A STABLE ICE MARGIN—EAST GREENLAND DURING THE MIDDLE AND UPPER PLEISTOCENE

Abstract

The East Greenland record of glaciation and environmental change is based on a combination of onshore and offshore studies. Glaciological work on contemporary outlet glaciers provides background for interpreting the glaciation styles of the past. The Scoresby Sund fjord system, the single largest outlet of the Inland Ice in East Greenland, and the adjacent continental shelf and slope, were the main working areas. The regionality of these results was tested with onshore and offshore work on sites further to the north in the East Greenland fjord zone. The record spans the period since Isotope Stage 7 (ca 240 ka). The most extensive glaciation phases were the Lollandselv and Scoresby Sund glaciations (Isotope Stages 7 and 6). The Langelandselv interglaciation (Isotope Substage 5e) comprises shallow marine sediments at more than 20 sites onshore, and Cibicides wuellerstorfii carrying sediments on the continental slope. Summer temperatures were 2–3° warmer than the Holocene optimum, and there was vigorous advection of warm Atlantic water into the fjords. The warm period seems to be accompanied by a eustatic sea-level rise of ca 20 m. During the Weichselian there were three major glacier advances, the Aucellaelv, Jyllandselv, and Flakkerhuk stades (Isotope Substages 5d, ?5b, and Stages 3–2). All three advances mark a shift from one topographically determined stable position to another. In each phase the glaciers occupied almost the same space in the fjord basins and had their fronts on the inner shelf. But the glacial regime and duration was different. The Aucellaelv stade lasted ca 10 ka, and the regime resembled that of present day outlet glaciers 600 km further to the north. The Flakkerhuk stade lasted for ca 50 ka, but left only thin and sporadic till, as well as glaciolacustrine sediments in ice-dammed river valleys. The regime was polar, similar to present day glaciers in Antarctica. Its culmination, the last glacial maximum, in the period between 22 and 14 ka, is shown by a maximum in IRD deposition on the continental slope. After 12 ka, and before 10 ka, the outer fjord basins in the southern fjord zone had been abandoned by the glaciers, and at ca 9.5 ka the last resurgence, the Milne Land stade, had ended.