MONITORING WATER MASS CHANGES IN THE NORTH ATLANTIC THROUGH MARINE PROXIES AT EIRIK AND GARDAR DRIFTS

The North Atlantic region plays a major role in climate change. Research has shown through geochemical and sedimentological marine proxies that the last glacial interval was notably different than today (Broecker, 1991; Hunter et al., 2007; Channel et al., 2014, and others). Changes in circulation have been observed during abrupt millennial-scale climate events that marked the last deglacial interval, such as Heinrich-1 (H1), the Younger Dryas (YD), and the Bølling-Allerød (BA; i.e., Hodell et al., 2009; 2015; Muschitiello et al., 2019). Understanding the surface and deep-water systems in this region are critical to understanding the mechanisms that control and initiate climate events.

This study is a paleontological, sedimentological and geochemical site survey of cores 15JPC (Eirik Drift; 2240m) and 13JPC (Gardar Drift; 3082cm). Downcore planktonic foraminiferal species counts were conducted to investigate rapid climate and water mass changes since the LGM to present. These cores were selected for their expanded sections from the last deglacial period, downstream proximity to deep-water sources such as Denmark-Scotland Overflow Water (DSOW) and Iceland-Scotland Overflow Water (ISOW) and high sedimentation rates. 13JPC has recently obtained 7 AMS ¹⁴C dates for better age control, planktonic δ¹⁸O and δ¹³C records, ice-rafted detritus counts, and calculated sedimentation rates. 15JPC additionally has benthic and planktonic δ¹⁸O and δ¹³C and percent coarse fraction records previously generated. The purpose of this study is to generate a comparable record between cores 13JPC and 15JPC in order to evaluate variations in water mass contributions since the LGM.

Initial results show the expected trends of cold-water species, Neogloboquadrina pachyderma (sinistral), dominating the record at core 15JPC while warm water species, Globigerina bulloides dominate warmer events and throughout core 13JPC. Observations of increased percent coarse fraction, IRD values, and high sedimentation rates at 13JPC during the YD were compared with increased δ¹³C values of benthic species, P. wuellerstorfi at 15JPC. This is interpreted as deep water being in a conveyor “on” mode during the YD. Results are consistent with this hypothesis at both 15JPC and 13JPC. Further work is needed in order to provide more insight into these trends and other future observations between these cores.