Study of millennial scale paleoclimatic and paleoceanographic changes in conjunction with variations in the East Greenland Current during the late Quaternary

Abstract

Sediment core HH13-089GC (497 cm), collected from the continental slope off Scoresby Sund, East Greenland has been investigated in order to study paleoclimatic and paleoceanographic changes in the area in conjunction with variations in the East Greenland Current during the late Quaternary. The results are based on a multiproxy analysis of the sediment core, including faunal investigations of planktic- and benthic foraminifera, grain size analysis and IRD, stable oxygen- and carbon isotope analysis, and magnetic susceptibility. The grain size of sortable silt was also analysed for the reconstruction of bottom current dynamics. An age model was established using AMS radiocarbon dates, in addition to ages for marine isotope stage boundaries from the global climate curve (Lisiecki and Raymo, 2005), interpreted by oxygen isotope stratigraphy. The stratigraphic interpretation and proxy results reviled the presence of marine isotope stages 1 – 5, and possibly the MIS 6/5 boundary. The isotope analysis was carried out on the planktic foraminifera N. pachyderma, and showed some excursions from the global curve, suggesting that certain climatic events where overridden by local/regional meltwater events. Retreats and advances of the Greenland Ice Sheet during the last ~ 130 000 years have been indicated by several major pulses of increased supply of IRD. Maximum values were reached during MIS 2 (~ 28 800 – 14 300 yrs. BP), which also includes the Last Glacial Maximum. Some of the major pulses are believed to be related to Heinrich Events based on their characteristics, ages, and correlation with the NGRIP ice core record and other marine records from the North Atlantic. All peaks in the IRD record correlated with the Greenland Stadials recorded in the NGRIP ice core record. The sortable silt record showed an interesting pattern, and was found to have a positive correlation with the climatic oscillations recorded in the NGRIP ice core record, and several magnetic susceptibility records from the North Atlantic. The sortable silt correlations indicated a relationship between large atmospheric climate variations and bottom current activity; where Greenland Interstadials correlated with increased current activity and high magnetic susceptibility, and Greenland Stadials correlated with reduced current activity and low magnetic susceptibility. The planktic and benthic foraminiferal records provided important paleoceanographic information, such as variations in surface productivity and ventilation, events of surface freshening, influence of warmer surface/sub-surface waters, sea ice coverage, nutrient supply, and energy changes in the bottom environment.