Abyssal origin for the early Holocene pulse of unradiogenic neodymium isotopes in Atlantic seawater ...

• Main Authors: Howe, JNW, Piotrowski, AM, Rennie, VCF
• Format: Article in Journal/Newspaper
• Language: English
• Published: Geological Society of America 2016
• Subjects: 3709 Physical Geography and Environmental Geoscience; 37 Earth Sciences; 3703 Geochemistry; 3705 Geology; 3706 Geophysics; 14 Life Below Water; Labrador Sea; North Atlantic Deep Water; North Atlantic; Northwest Atlantic
• Online Access: https://dx.doi.org/10.17863/cam.4565; https://www.repository.cam.ac.uk/handle/1810/260334

Abstract The neodymium isotopic composition of authigenic phases of deep-sea sediment cores can be interpreted as reflecting past changes in water-mass mixing proportions if end-member water-mass compositions are constrained through time. Here we present three new records spanning 2480 to 4360 m depth in the North Atlantic Ocean that show seawater Nd isotope values in the early to mid-Holocene that are more radiogenic than values from the abyssal northwest Atlantic. This finding indicates that that the end-member composition of North Atlantic Deep Water was more stable within its core than it was at abyssal depths. The spatial distribution of the unradiogenic neodymium isotope values observed in the North Atlantic suggests a bottom source, and therefore that they were unlikely to have been due to the production of intermediate-depth Labrador Sea Water. We infer that the unradiogenic authigenic Nd isotope values were most likely derived from a pulse of poorly chemically weathered detrital material that was ...