CHARACTERIZING SURFACE WATER CHANGES ON EIRIK AND GARDAR DRIFTS THROUGH PLANKTONIC FORAMINIFERAL SPECIES COUNTS

The North Atlantic region plays a critical role in climate change. Research through geochemical and sedimentological marine proxies have shown that the last glacial interval was different than today (Broecker, 1991; Hunter et al., 2007; Channel et al., 2014, and others). Shifts in circulation have been observed during abrupt millennial-scale climate events that punctuated 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 the North Atlantic Ocean are crucial to understanding the mechanisms that control and initiate climate events.

This study is a paleontological, sedimentological and geochemical analysis 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 Last Glacial Maximum 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 records and percent coarse fraction records previously generated. The purpose of this study is to generate a comparable record between cores 13JPC and 15JPC 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 two intervals of diatom mats with high sedimentation rates and little to no foraminiferal assemblages present indicate that core 13JPC is missing the YD. Comparisons of oxygen isotopic data to another core (11JPC; 56°14’N, 27°39’W; Gardar Drift) and 15JPC are consistent with this hypothesis. Further work is needed in order to provide more insight into these trends and other future observations between these cores.