The timing and properties of deep water exchange between the Nordic Seas and open North Atlantic during the last 20,000 years

• Main Authors: Thornally, David J., Barker, Stephen, Bauch, Henning A., Elderfield, Henry, Skinner, Luke, Yu, Jimin
• Format: Conference Object
• Language: unknown
• Published: 2012
• Subjects: Greenland; Greenland-Scotland Ridge; Iceland; Nordic Seas; North Atlantic; Northeast Atlantic
• Online Access: https://oceanrep.geomar.de/id/eprint/20675/

PP43C-06 Deepwater formation in the North Atlantic is an essential component of the overturning circulation of the Atlantic Ocean, which helps regulate global climate. Paleoceanographic studies have revealed that deep water formation in the North Atlantic was altered during the last ice age as compared with today; although the circulation of the North Atlantic during the subsequent deglaciation remains poorly constrained. In order to understand the mechanisms by which deglaciation proceeded, it is crucial that we further investigate the timing and nature of North Atlantic circulation changes. Much of the uncertainty surrounding the circulation of the deglacial Northeast Atlantic centres on the cause of mid-depth low benthic δ18O recorded during Heinrich Stadial 1, and episodic incursions of an extremely 14C-depleted (i.e., poorly ventilated) water mass in the Northeast Atlantic. Existing proxy data are insufficient to unambiguously resolve the cause of these ‘anomalies’ and models typically fail to reconstruct such variability. To investigate the cause of these events, we have reconstructed deep water temperature, δ18O, δ13C and Δ14C at sites in the Northeast Atlantic and deep Norwegian Seas over the past 20ka. Using our multi-proxy datasets from north and south of the Greenland-Scotland ridge we robustly constrain the timing and properties of water mass exchange across the Iceland-Scotland Ridge. We deconvolve the temperature and seawater δ18O signals contained within the benthic δ18O records and examine the source and subsequent spreading of highly 14C-depleted water.