Abstract
Neodymium isotopic composition and rare earth element concentrations in the deep and intermediate Nordic Seas: Constraints on the Iceland Scotland Overflow Water signature
LEGOS, Observatoire Midi Pyrénées, 14 avenue E. Belin, Toulouse, 31400 France
LEGOS, Observatoire Midi Pyrénées, 14 avenue E. Belin, Toulouse, 31400 France
Neodymium isotopic composition and rare earth element concentrations were measured in seawater samples from eleven stations
in the Nordic Seas. These data allow us to study how the Iceland Scotland Overflow Water (ISOW) acquires its neodymium signature
in the modern ocean. The waters overflowing the Faroe Shetland channel are characterized by
Nd = −8.2 ± 0.6, in good agreement with the only other data point, published 19 years ago. In the Greenland and Iceland Seas
the water masses leading to the formation of the ISOW display lower neodymium isotopic composition, with
Nd around −11 and −9, respectively. Since no water masses in the Nordic Seas are characterized by
Nd > −8, the radiogenic signature of the ISOW likely reflects inputs from the highly radiogenic Norwegian Basin basaltic margins
(Jan-Mayen, Iceland, Faroe, with
Nd ≈ +7). In addition to the neodymium isotopic composition, the rare earth element patterns suggest that these inputs occur
via the remobilization (which includes resuspension and dissolution) of sediments deposited on the margins. Whereas the neodymium
isotopic composition behaves conservatively in the oceans in the absence of lithogenic inputs, and can be used as a water
mass tracer, these results emphasize the role of interactions, between sediments deposited on margins and seawater, in the
acquisition of the neodymium isotopic composition of water masses. These results should allow a better use of this parameter
to trace the present and the past circulation in the North Atlantic.
Received 9 April 2004; accepted 20 September 2004; published 6 November 2004.
Citation: (2004), Neodymium isotopic composition and rare earth element concentrations in the deep and intermediate Nordic Seas: Constraints on the Iceland Scotland Overflow Water signature, Geochem. Geophys. Geosyst., 5, Q11006, doi:10.1029/2004GC000742.
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