Early Holocene palaeoceanography and deglacial chronology of Disko Bugt, West Greenland

Abstract

Two new cores from Disko Bugt, a large marine embayment in West Greenland, are used to assess the deglacial chronology and palaeoceanography of the area during the early Holocene. Deglaciation of the main part of Disko Bugt is directly dated for the first time to a minimum of ca 10.2 ka cal. BP. By this time the Jakobshavn Isbrae ice stream had retreated to the eastern margins of Disko Bugt. Initial deglaciation took place before the relatively warm West Greenland Current (WGC) was initiated. A strengthening in the WGC is identified from ca 9.2 ka cal. BP accompanied by retreat of the ice stream to a shallow bank immediately west of the present day Jakobshavn Isfjord. While in this position the calving and melting ice stream produced large volumes of sediment and meltwater. The large volumes of meltwater prevented the relatively warm waters of the WGC reaching the eastern margins of Disko Bugt. The ice stream remained grounded on this bank for over a thousand years until ca 7.9 ka cal. BP when reduced sedimentation rates and an increase in boreal fauna point to its retreat inside the present day fjord system.