Using Foraminiferal Nd Isotope Records to Test the Paradigm for Deglacial Atlantic Deepwater Variability

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Deepwater export from the northern North Atlantic to the ocean interior is widely believed to have decreased significantly during cold events of the last deglaciation (Heinrich Event 1 and the Younger Dryas). Motivated by recent debate on the topic, the proposed work will produce a novel reconstruction of Atlantic deglacial circulation based on well-dated records of neodymium isotope composition spanning the last ~25,000 years. These records will be developed from analyses of planktonic foraminifera from three depth transects in the western Atlantic (north, tropical, south). In combination with benthic oxygen and carbon isotope measurements, the neodymium isotope records will be used to 1) constrain potential end-member changes, 2) determine water mass variability in the upper, mid-depth, and deep Atlantic, and 3) evaluate the current paradigm of deglacial deepwater variability. This work will advance the understanding of ocean circulation dynamics related to abrupt climate change. The project will support cross-disciplinary collaboration between a senior scientist and an early-career investigator at Woods Hole Oceanographic Institution. Undergraduate and high school students will be trained in laboratory techniques. In addition, ten high school students from diverse backgrounds will be engaged through a one-week internship facilitated by the PI in collaboration with a local high school teacher.