HOLOCENE EVOLUTION OF DISKO BUGT, WEST GREENLAND

The wide ice-free margin of the west coast of Greenland (between 150 and 200km wide) supports a rich array of glacial landforms. Numerous radiocarbon dates, mostly on molluscs contained in raised glacio-marine deposits, provide a chronology of advance and retreat of the Greenland ice sheet since the last glacial maximum. A prominent element of this deglacial history is the widespread ‘Fjord Stage’ moraine. This is dated to c. 9.3ka cal. BP and formed in response to either a short lived climatic deterioration or because of topographic controls on ice sheet retreat. In this paper we use data derived from offshore gravity cores to explore the correlation between terrestrial models of deglaciation and the oceanographic record of environmental change in Disko Bugt.

Foraminiferal and sedimentological data show a clear oceanographic change dated 9.4 – 8.9 ka cal BP which is similar in age to the ‘Fjord Stage’. This event is marked by a switch from colder water foraminifera to a warmer assemblage, more similar to the present day, which may relate to the incursion of the relatively warm and saline West Greenland Current into Disko Bugt. The switch to warmer conditions at the time when the terrestrial evidence points to climate cooling is contradictory. Our work suggests that the ‘Fjord Stage’ in Disko Bugt occurred later than previously thought (as also suggested by new relative sea-level data collected from the south of the bay). Under this scenario, the oceanographic evidence we report most probably records the influx of warmer water following the retreat of the ice sheet to the eastern shores of Disko Bugt during the early Holocene.