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The global variation in the iron isotope composition of marine hydrogenetic ferromanganese deposits: Implications for seawater chemistry?

Earth and Planetary Science Letters

By:
, , ,
DOI: 10.1016/j.epsl.2004.05.010

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Abstract

The iron (Fe) isotope compositions of 37 hydrogenetic ferromanganese deposits from various oceans have been analysed by MC-ICPMS; they permit the construction of a global map of Fe isotopic values. The isotopic compositions range between -1.2 and -0.1??? in ??57FeIRMM14. Averages for the Atlantic and the Pacific are -0.41 and -0.88???, but their standard deviations are identical (0.27, 1 ??) and the data very largely overlap. No correlation is found with Pb or Nd isotope compositions and there is no evidence that the observed oceanic Fe isotopic heterogeneity is directly controlled by variations in continental sources. The small quantities of Fe that can be introduced from hydrothermal sources render as unlikely the possibility that the isotopic variations reflect variable proportions of continental and hydrothermal Fe, as recently proposed. The more likely explanation is that the variations are induced locally within the ocean. The exact sources of fractionation remain unclear. Likely possibilities are the dissolution and reprecipitation processes that liberate Fe from sediments during anoxic events, dissolution in surface waters or processes occurring during growth of the crusts. ?? 2004 Elsevier B.V. All rights reserved.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
The global variation in the iron isotope composition of marine hydrogenetic ferromanganese deposits: Implications for seawater chemistry?
Series title:
Earth and Planetary Science Letters
DOI:
10.1016/j.epsl.2004.05.010
Volume
224
Issue:
1-2
Year Published:
2004
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Earth and Planetary Science Letters
First page:
91
Last page:
105
Number of Pages:
15