Elsevier

Chemical Geology

Volume 47, Issues 1–2, 30 November 1984, Pages 113-133
Chemical Geology

Research paper
Metal variations in divergent plate-boundary sediments from the Pacific

https://doi.org/10.1016/0009-2541(84)90102-5Get rights and content

Abstract

One hundred and three deep-sea sediments have been recovered on traverses along the East Pacific Rise (EPR), between 3° and 20°S, and the Galápagos Rift System (GRS), between 86° and 102°W. Analyses of 23 elements by instrumental neutron activation revealed that Co, Zn, As and Sb covary with Fe, suggesting probable adsorption of these metals from seawater onto Fe-oxyhydroxides. As was found to be significantly higher in EPR sediments, probably due to hydrothermal As input. Sb and Zn are especially enriched in the sediments of the easternmost traverse of the GRS, near the hydrothermal mounds area. Chemical gradients of some metals with depth in the sediments were found. In particular, U enrichment occurs in sediments from the EPR at ∼13°S, and Zn and Sb enrichment with depth is observed in the sediments near the hydrothermal mounds area. Rare-earth elements (REE) contents of sediments are low compared to pelagic clay, but EPR sediments have slightly higher REE than GRS sediments. Trivalent REE correlate with Fe and the same is observed for Ce. GRS sediments have, however, higher Ce contents suggesting, probably, an additional, biogenic input for Ce in equatorial Pacific regions. A number of EPR and GRS sediments have significant Au (10–20 ppb), and some of the sediments have relatively high Ag (up to 13 ppm).

References (39)

  • E.D. Goldberg et al.

    Geochemistry of Pacific pelagic sediments

    Geochim. Cosmochim. Acta

    (1958)
  • P. Lonsdale

    Deep-tow observations at the Mounds Abyssal Hydrothermal Field, Galapagos Rift

    Earth Planet. Sci. Lett.

    (1977)
  • V. Marchig et al.

    Iron-rich metalliferous sediments on the East Pacific Rise: prototype of undifferentiated metalliferous sediments on divergent plate boundaries

    Earth Planet. Sci. Lett.

    (1982)
  • M.A. Meylan et al.

    Metalliferous deepsea sediments

  • D.Z. Piper

    Origin of metalliferous sediments from the East Pacific Rise

    Earth Planet. Sci. Lett.

    (1973)
  • F.L. Sayles et al.

    Ferromanganoan sediments in the equatorial East Pacific

    Earth Planet. Sci. Lett.

    (1973)
  • W. Schmitz et al.

    Hydrothermal serpentine in a Hess Deep sediment core

    Mar. Geol.

    (1982)
  • H. Bäcker

    Lagerstättenbildung an divergenten Plattengrenzen

    Erzmetall

    (1982)
  • J.L. Bischoff et al.

    Geochemistry of deep-sea sediments from the Pacific Manganese Nodule Province: Domes Sites A, B, and C

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