Molybdenum isotopes in hydrothermal manganese crust from the Ryukyu arc system

Implications for the source of molybdenum

Kosuke T. Goto, Gen Shimoda, Ariel Anbar, Gwyneth Gordon, Yumiko Harigane, Ryoko Senda, Katsuhiko Suzuki

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

A high concentration of molybdenum (Mo) is a striking feature of modern marine hydrothermal manganese (Mn) crusts from both low- and high-temperature hydrothermal systems; however, the origin of that Mo is poorly constrained. In this study, we analyzed Mo isotopic composition (δ<sup>98/95</sup>Mo) in a Mn crust collected from the Ryukyu arc system, and assessed the possible use of δ<sup>98/95</sup>Mo to constrain the origin of Mo in hydrothermal Mn crusts. Along with Mo isotope analysis, we also measured the abundance of major and trace elements and the Re-Os isotopic composition. The Mn crust sample had a high Mn content (42%-47%) and was low in Fe (0.2%-0.5%). Among the manganophile elements (Co, Ni, Cu, Zn, and Mo), only Mo showed high concentrations (>550ppm). We also found low contents of Os (~35ppt) with an isotopic composition of <sup>187</sup>Os/<sup>188</sup>Os=~1.00. These results are consistent with previously reported chemical compositions of hydrothermal Mn crusts. δ<sup>98/95</sup>Mo values in the sample ranged from -0.56‰ to -0.66‰, which are ~2.7‰ lighter than the present-day seawater δ<sup>98/95</sup>Mo but similar to those in modern hydrogenous Fe-Mn crusts and Mn nodules. Although current data do not preclude the possible contribution of hydrothermally derived Mo, the light δ<sup>98/95</sup>Mo values can be explained by isotope fractionation associated with a change in coordination number during the adsorption of Mo from seawater onto Mn oxides. We suggest that the δ<sup>98/95</sup>Mo data are useful for constraining the source of Mo in hydrothermal Mn crusts.

Original languageEnglish (US)
Pages (from-to)91-99
Number of pages9
JournalMarine Geology
Volume369
DOIs
StatePublished - Nov 1 2015

Fingerprint

Molybdenum
Manganese
molybdenum
Isotopes
manganese
isotope
crust
isotopic composition
Chemical analysis
Seawater
Manganese nodules
seawater
manganese nodule
manganese oxide
Trace Elements
Fractionation
hydrothermal system
fractionation
chemical composition
trace element

Keywords

  • Hydrothermal manganese crust
  • Manganophile element
  • Molybdenum isotope
  • Osmium isotope
  • Ryukyu arc system

ASJC Scopus subject areas

  • Oceanography
  • Geochemistry and Petrology
  • Geology

Cite this

Molybdenum isotopes in hydrothermal manganese crust from the Ryukyu arc system : Implications for the source of molybdenum. / Goto, Kosuke T.; Shimoda, Gen; Anbar, Ariel; Gordon, Gwyneth; Harigane, Yumiko; Senda, Ryoko; Suzuki, Katsuhiko.

In: Marine Geology, Vol. 369, 01.11.2015, p. 91-99.

Research output: Contribution to journalArticle

Goto, Kosuke T. ; Shimoda, Gen ; Anbar, Ariel ; Gordon, Gwyneth ; Harigane, Yumiko ; Senda, Ryoko ; Suzuki, Katsuhiko. / Molybdenum isotopes in hydrothermal manganese crust from the Ryukyu arc system : Implications for the source of molybdenum. In: Marine Geology. 2015 ; Vol. 369. pp. 91-99.
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abstract = "A high concentration of molybdenum (Mo) is a striking feature of modern marine hydrothermal manganese (Mn) crusts from both low- and high-temperature hydrothermal systems; however, the origin of that Mo is poorly constrained. In this study, we analyzed Mo isotopic composition (δ98/95Mo) in a Mn crust collected from the Ryukyu arc system, and assessed the possible use of δ98/95Mo to constrain the origin of Mo in hydrothermal Mn crusts. Along with Mo isotope analysis, we also measured the abundance of major and trace elements and the Re-Os isotopic composition. The Mn crust sample had a high Mn content (42{\%}-47{\%}) and was low in Fe (0.2{\%}-0.5{\%}). Among the manganophile elements (Co, Ni, Cu, Zn, and Mo), only Mo showed high concentrations (>550ppm). We also found low contents of Os (~35ppt) with an isotopic composition of 187Os/188Os=~1.00. These results are consistent with previously reported chemical compositions of hydrothermal Mn crusts. δ98/95Mo values in the sample ranged from -0.56‰ to -0.66‰, which are ~2.7‰ lighter than the present-day seawater δ98/95Mo but similar to those in modern hydrogenous Fe-Mn crusts and Mn nodules. Although current data do not preclude the possible contribution of hydrothermally derived Mo, the light δ98/95Mo values can be explained by isotope fractionation associated with a change in coordination number during the adsorption of Mo from seawater onto Mn oxides. We suggest that the δ98/95Mo data are useful for constraining the source of Mo in hydrothermal Mn crusts.",
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T2 - Implications for the source of molybdenum

AU - Goto, Kosuke T.

AU - Shimoda, Gen

AU - Anbar, Ariel

AU - Gordon, Gwyneth

AU - Harigane, Yumiko

AU - Senda, Ryoko

AU - Suzuki, Katsuhiko

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AB - A high concentration of molybdenum (Mo) is a striking feature of modern marine hydrothermal manganese (Mn) crusts from both low- and high-temperature hydrothermal systems; however, the origin of that Mo is poorly constrained. In this study, we analyzed Mo isotopic composition (δ98/95Mo) in a Mn crust collected from the Ryukyu arc system, and assessed the possible use of δ98/95Mo to constrain the origin of Mo in hydrothermal Mn crusts. Along with Mo isotope analysis, we also measured the abundance of major and trace elements and the Re-Os isotopic composition. The Mn crust sample had a high Mn content (42%-47%) and was low in Fe (0.2%-0.5%). Among the manganophile elements (Co, Ni, Cu, Zn, and Mo), only Mo showed high concentrations (>550ppm). We also found low contents of Os (~35ppt) with an isotopic composition of 187Os/188Os=~1.00. These results are consistent with previously reported chemical compositions of hydrothermal Mn crusts. δ98/95Mo values in the sample ranged from -0.56‰ to -0.66‰, which are ~2.7‰ lighter than the present-day seawater δ98/95Mo but similar to those in modern hydrogenous Fe-Mn crusts and Mn nodules. Although current data do not preclude the possible contribution of hydrothermally derived Mo, the light δ98/95Mo values can be explained by isotope fractionation associated with a change in coordination number during the adsorption of Mo from seawater onto Mn oxides. We suggest that the δ98/95Mo data are useful for constraining the source of Mo in hydrothermal Mn crusts.

KW - Hydrothermal manganese crust

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KW - Osmium isotope

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