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Site U1554 is located on Björn drift, on the eastern flank of the Reykjanes Ridge in the North Atlantic Ocean. The Reykjanes Ridge flanks host a series of crustal V-shaped ridges (VSRs) and V-shaped troughs (VSTs) (Figure F1), whose origins and relation with Iceland mantle plume temperature variations are debated. Site U1554 is located on VST 2b, identifiable in the free-air gravity anomaly map and the reflection seismic profile (Figure F2). It sits on ocean crust with an age of 12.7 Ma estimated from magnetic anomalies and plate reconstruction models. The Reykjanes Ridge flanks are also the site of major drift deposits: Björn and Gardar drifts on the eastern flank of the ridge and Eirik drift on the eastern flank of the Greenland margin. These rapidly accumulated contourite drift sediments have the potential to record variations in past climate and ocean circulation on millennial timescales. The sedimentation rate of the drifts can serve as a proxy for deep water current strength, providing information on oceanic gateways to the Norwegian Sea and their potential ties to Iceland mantle plume behavior.
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This content will become publicly available on May 5, 2026
Onset of strong Iceland-Scotland overflow water 3.6 million years ago
North Atlantic Deep Water (NADW), the return flow component of the Atlantic Meridional Overturning Circulation (AMOC), is a major inter-hemispheric ocean water mass with strong climate effects but the evolution of its source components on million-year timescales is poorly known. Today, two major NADW components that flow southward over volcanic ridges to the east and west of Iceland are associated with distinct contourite drift systems that are forming off the coast of Greenland and on the eastern flank of the Reykjanes (mid-Atlantic) Ridge. Here we provide direct records of the early history of this drift sedimentation based on cores collected during International Ocean Discovery Programme (IODP) Expeditions 395C and 395. We find rapid acceleration of drift deposition linked to the eastern component of NADW, known as Iceland–Scotland Overflow Water at 3.6 million years ago (Ma). In contrast, the Denmark Strait Overflow Water feeding the western Eirik Drift has been persistent since the Late Miocene. These observations constrain the long-term evolution of the two NADW components, revealing their contrasting independent histories and allowing their links with climatic events such as Northern Hemisphere cooling at 3.6 Ma, to be assessed.
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- Award ID(s):
- 2238290
- PAR ID:
- 10591695
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Springer Nature
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 16
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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