4 High latitude paleoceanographic discoveries from Scientific Ocean Drilling (IODP, ODP, DSDP)

Scientific Ocean Drilling has retrieved thousands of meters of sediment cores from the high latitude oceans.  This session provides the opportunity to present the results of work to understand Cenozoic climate and oceanographic changes.

Sunday, 22 March 2026
8:00 AM - 12:00 PM
CCC, Room 27

Reconstructing North Atlantic Deep Water Variability Under Pliocene Warm Climates: Evidence from IODP Site U1564

Paper number: 4-3
Program: Technical Sessions
Time: 8:45 AM – 9:05 AM

Authors

Abstract

The early–mid Pliocene (~5.3–3 Ma) represents a key warm interval in Earth’s climate history, preceding major Northern Hemisphere glaciation. Global temperatures were ~2–4 °C higher than today (e.g., Dowsett et al., 2010; Haywood et al., 2016), atmospheric CO₂ was comparable to modern levels (e.g., Badger et al., 2013), and ice sheets in Greenland and West Antarctica were substantially reduced (e.g., Dolan et al., 2015; Berends et al., 2019), contributing to elevated sea levels. Past proxy and model studies suggest that the Atlantic Meridional Overturning Circulation (AMOC) was stronger during these warm intervals, potentially amplifying global heat transport (e.g., Raymo et al., 1996; Zhang et al., 2021). However, direct constraints on North Atlantic bottom-current velocity for this period remain scarce.

 

We present a continuous ~4.5–3 Ma record of deep-water flow strength from Gardar Drift sediments at IODP Site U1564 (59.9°N, 23.3°W; 2208 m), a major pathway for Iceland–Scotland Overflow Water (ISOW), the principal lower branch of North Atlantic Deep Water (NADW). Using sortable silt grain-size measurements and ln(Zr/Rb) ratios, we reconstruct variations in ISOW vigor across two major warm intervals: the Pliocene Climate Optimum (~4.4–4 Ma) and the mid-Pliocene Warm Period (~3.3–3 Ma). These data provide the first high-resolution velocity reconstructions from the Gardar Drift for this interval, revealing shifts in deep-water export from the Nordic Seas and the behavior of AMOC under sustained warm climate conditions. The results clarify the sensitivity of NADW formation during past warm periods and offer a paleoceanographic framework for evaluating potential future changes in AMOC strength.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411166

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