Nd isotope data for ODP Leg 208 holes

• Main Authors: Via, Rachael K, Thomas, Deborah J
• Format: Other/Unknown Material
• Language: English
• Published: PANGAEA 2006
• Subjects: 208-1262A; 208-1263A; 208-1264A; DRILL; Drilling/drill rig; Joides Resolution; Leg208; Ocean Drilling Program; ODP; Walvis Ridge; Southeast Atlantic Ocean; Greenland; North Atlantic Deep Water; North Atlantic; Norwegian Sea; Southern Ocean
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.724682; https://doi.org/10.1594/PANGAEA.724682

The flow of deep-water masses is a key component of heat transport in the modern climate system, yet the role of deep-ocean heat transport during periods of extreme warmth is poorly understood. The present mode of meridional overturning circulation is characterized by deep-water formation in both the North Atlantic and the Southern Ocean. However, a different mode of meridional overturning circulation operated during the extreme greenhouse warmth of the early Cenozoic, during which time the Southern Ocean was the dominant region of deep-water formation. The combination of general global cooling and tectonic evolution of the Atlantic basins over the past ~55 m.y. ultimately led to the development of a mode of overturning circulation characterized by both Southern Ocean and North Atlantic deep-water sources. The change in deep-water circulation mode may, in turn, have affected global climate; however, unraveling the causes and consequences of this transition requires a better understanding of the timing of the transition. New Nd isotope data from the southeastern Atlantic Ocean indicate that the initial transition to a bipolar mode of deep-water circulation occurred in the early Oligocene, ca. 33 Ma. The likely cause of significant deep-water production in the North Atlantic was tectonic deepening of the sill separating the Greenland-Norwegian Sea from the North Atlantic.