The 8200 cal. yr BP event reflected in the Arctic fjord, Van Mijenfjorden, Svalbard

Abstract

Detailed stratigraphic investigations of a high-resolution sediment core from the Arctic fjord, Van Mijenfjorden, Svalbard, reveal significant reductions in benthic foraminiferal δ18O of 0.4‰ and 0.2—0.3‰ dated to c. 8200 and 8450 cal. yr BP, respectively. These reductions, combined with changes in the benthic foraminiferal fauna and IRD, indicate substantial changes in the hydrography of the fjord, such as freshening of the bottom water, enhanced sea ice distribution and reduced biogenic production. The age and duration (~100 years) of the youngest event is directly in phase with the 8200 cal. yr anomaly in the δ18O record GISP2 and NGRIP of the Greenland Ice Sheet. The changes around 8450 cal. yr BP compare well to the timing of the initial freshwater drainage of the proglacial Lake Agassiz. Therefore the proxy record of Van Mijenfjorden lends support to the theory, explaining the 8200 cal. yr BP event as a cumulative response to a freshwater-forced reduction in the meridional overturning circulation in the North Atlantic. A reduction in the meridional overturning circulation (MOC) may have changed the oceanic inflow to the fjord towards reduced influence of Atlantic Water and increased the dominance of fresher Arctic Water.