Molybdenum behavior during early diagenesis

Insights from Mo isotopes

Rebecca L.Poulson Brucker, James McManus, Silke Severmann, William M. Berelson

Research output: Contribution to journalArticle

93 Citations (Scopus)

Abstract

We present molybdenum isotope and concentration data from 14 sites in the eastern Pacific from the central California to the Peru margin. The environments studied have been chosen to represent a broad range in oxidation-reduction (redox) potential, which provide a framework for the behavior of this redoxsensitive element. Manganese-rich hemipelagic sediments from the eastern tropical Pacific have a mean characteristic Mo isotope signature (δ98/95Mo =-0.49 ± 0.04%, two times the standard deviation of the mean (2 SDOM) with n = 14) that reflects fractionation between ocean water and authigenic Mo associated with Mn oxides. Authigenic Fe-Mo-S deposits from reducing continental margin settings also have a characteristic Mo isotopic signature (δ98/95Mo = 1.64 ± 0.04%, 2 SDOM with n = 136). Both of these values are in contrast to highly sulfidic (>11 μM H2Saq) restricted basin environments, which contain Mo isotope values analytically indistinguishable from seawater. In terms of the Mo isotope composition, the modern oceanic Mo sink is dominated by continental margin "type" environments where δ98/95 = ̃1.6% and Mn-rich sediments where δ98/95Mo = approximately-0.5%, with a minor contribution from euxinic settings where H2Saq > 11 μM.

Original languageEnglish (US)
Article numberQ06010
JournalGeochemistry, Geophysics, Geosystems
Volume10
Issue number6
DOIs
StatePublished - Jun 1 2009

Fingerprint

Molybdenum
molybdenum
Isotopes
diagenesis
isotopes
isotope
continental shelves
sediments
molybdenum isotopes
signatures
continental margin
Peru
Sediments
sinks
fractionation
manganese
margins
standard deviation
oceans
redox potential

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

Keywords

  • Diagenesis
  • Isotopes
  • Molybdenum

Cite this

Brucker, Rebecca L.Poulson ; McManus, James ; Severmann, Silke ; Berelson, William M. / Molybdenum behavior during early diagenesis : Insights from Mo isotopes. In: Geochemistry, Geophysics, Geosystems. 2009 ; Vol. 10, No. 6.
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Molybdenum behavior during early diagenesis : Insights from Mo isotopes. / Brucker, Rebecca L.Poulson; McManus, James; Severmann, Silke; Berelson, William M.

In: Geochemistry, Geophysics, Geosystems, Vol. 10, No. 6, Q06010, 01.06.2009.

Research output: Contribution to journalArticle

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AB - We present molybdenum isotope and concentration data from 14 sites in the eastern Pacific from the central California to the Peru margin. The environments studied have been chosen to represent a broad range in oxidation-reduction (redox) potential, which provide a framework for the behavior of this redoxsensitive element. Manganese-rich hemipelagic sediments from the eastern tropical Pacific have a mean characteristic Mo isotope signature (δ98/95Mo =-0.49 ± 0.04%, two times the standard deviation of the mean (2 SDOM) with n = 14) that reflects fractionation between ocean water and authigenic Mo associated with Mn oxides. Authigenic Fe-Mo-S deposits from reducing continental margin settings also have a characteristic Mo isotopic signature (δ98/95Mo = 1.64 ± 0.04%, 2 SDOM with n = 136). Both of these values are in contrast to highly sulfidic (>11 μM H2Saq) restricted basin environments, which contain Mo isotope values analytically indistinguishable from seawater. In terms of the Mo isotope composition, the modern oceanic Mo sink is dominated by continental margin "type" environments where δ98/95 = ̃1.6% and Mn-rich sediments where δ98/95Mo = approximately-0.5%, with a minor contribution from euxinic settings where H2Saq > 11 μM.

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