Late Quaternary palaeoceanography in Disko Bugt, West Greenland

• Main Author: Park, Laura Anne
• Published: Durham University 2003
• Subjects: 551.461342
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421804

This thesis uses foraminiferal, sedimentological and isotope analysis from three piston cores from different depositional environments in Disko Bugt, West Greenland to understand the nature of the relationship between deglacial activity and palaeo-water mass circulation. It has increased the spatial and temporal resolution of marine multiproxy data in the region through the development of a tight radiocarbon chronology. High resolution sampling has furthered the understanding of modes of Holocene palaeoceanographic irculation in Disko Bugt and West Greenland,a nd linked them to likely operating mechanisms of change. Information about past variations in the strength of the dominant water current in West Greenland (the West Greenland Current - WGC), has been successful through the application of foraminiferal water mass indicator species and isotope techniques. New dating relating to the timing of the final retreat of Jakobshavns Isbrae, the most important ice stream draining the West Greenland Ice Sheet, has been determined through evidence of meltwater and sediment fluxes from the calving margin. The high resolution records produced in this thesis clearly document the rapid instability and subsequent retreat of the ice stream to be related to rapid atmospheric warming following the well-documented "8.2 event". Mid-Holocene climatic changes are recorded in the fjord mouth setting of Kangersuneq. Despite considerable dissolution processes operating in the fjord (which are in fact a product of climatic change themselves), a high resolution record of variable and declining warmth of the WGC is recorded from c. 6.3 ka cal BP, prior to the onset of full Neoglacial conditions around 4.1 ka cal BP. The maximum cooling during the Neoglacial period is clearly seen from c. 3.2 to 2.2 ka cal BP in two cores. A distinct warming of the WGC takes place around 2.2 ka cal BP, which can be linked to an increased component of Irminger Current Water. This is also seen in the records from East Greenland and the Nordic Seas. The foraminiferal assemblagesfr om one of the cores show evidence of a distinct climatic amelioration which is associated with the Medieval Warm Period. There is some evidence for a deterioration of oceanographic conditions which is linked to the onset of the Little Ice Age.