Glacial-interglacial circulation changes inferred from 231Pa/ 230Th sedimentary record in the North Atlantic region ...

• Main Author: Francois, Roger
• Format: Text
• Language: English
• Published: American Geophysical Union 2017
• Subjects: North Atlantic
• Online Access: https://dx.doi.org/10.14288/1.0078394; https://doi.library.ubc.ca/10.14288/1.0078394

Studies from the subtropical western and eastern Atlantic Ocean, using the 231Pa/230Th ratio as a kinematic proxy for deep water circulation, provided compelling evidence for a strong link between climate and the rate of meridional overturning circulation (MOC) over the last deglaciation. In this study, we present a compilation of existing and new sedimentary 231Pa/230Th records from North Atlantic cores between 1710 and 4550 m water depth. Comparing sedimentary 231Pa/230Th from different depths provides new insights into the evolution of the geometry and rate of deep water formation in the North Atlantic during the last 20,000 years. The 231Pa/230Th ratio measured in upper Holocene sediments indicates slow water renewal above ~2500 m and rapid flushing below, consistent with our understanding of modern circulation. In contrast, during the Last Glacial Maximum (LGM), Glacial North Atlantic Intermediate Water (GNAIW) drove a rapid overturning circulation to a depth of at least ~3000 m depth. Below ~4000 m, ...