Influence of the Mediterranean outflow on the isotopic composition of neodymium in waters of the North Atlantic

Journal Article · Wed Jul 20 04:00:00 EDT 1983 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JC088iC10p05997· OSTI ID:5677980

Piepgras, D J; Wasserburg, G J

The isotopic composition of neodymium in the water column of the eastern North Atlantic near the Strait of Gibraltar has been determined for several depths. The data show outflow results in a significant shift in epsilon/sub Nd/(0) toward more radiogenic values of /sup 143/Nd//sup 144/Nd in the water column at a 1000-m depth. This corresponds to a depth in the neighborhood of the salinity maximum associated with the Mediterranean outflow. The core of the Mediterranean outflow gives epsilon/sub Nd/(0) = -9.8, as compared to epsilon/sub Nd/(0)roughly-equal-12 in overlying and underlying waters. From mixing considerations we estimate that pure Mediterranean waters have epsilon/sub Nd/(0)roughly-equal-6. Possible sources of this relatively radiogenic Nd could be from drainage of young continental terranes or the intection of remobilized Nd from deep-sea sediments that have a young radiogenic volcanic component. New data from a depth profile in the western Atlantic is presented. Comparison of Nd data for the eastern North Atlantic with that for the western North Atlantic shows fundamental differences in the water column structures for epsilon/sub Nd/(0). While both regions show a pronounced maximum in epsilon/sub Nd/(0), the western basin maximum occurs at the near surface rather than at 1000 m. In addition, deep waters of the eastern basin are found to be more radiogenic than the western basin. These differences indicate several sources of isotopically distinct Nd in the North Atlantic. The deep waters of the North Atlantic (>1000 m) have the lowest values of epsilon/sub Nd/(0) measured in the oceans. We believe that the source of these low epsilon/sub Nd/(0) values, which we associate with North Atlantic deep water, is either from freshwater drainage off the Precambrian shields of North America and Asia into the Arctic Ocean or from the injection of ''older,'' continentally derived REE from deep-sea sediments.

• Research Organization: The Lunatic Asylum of the Charles Arms Laboratory, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125
• OSTI ID: 5677980
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 88:C10; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580500* -- Oceanography-- (1980-1989)
ALPHA DECAY RADIOISOTOPES
ATLANTIC OCEAN
ELEMENTS
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FLUID FLOW
INTERMEDIATE MASS NUCLEI
ISOTOPE RATIO
ISOTOPES
MEDITERRANEAN SEA
METALS
NEODYMIUM
NEODYMIUM 143
NEODYMIUM 144
NEODYMIUM ISOTOPES
NUCLEI
RADIOISOTOPES
RARE EARTH NUCLEI
RARE EARTHS
SEAS
STABLE ISOTOPES
SURFACE WATERS
YEARS LIVING RADIOISOTOPES