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  • Data  (3)
  • Dredge; DRG; Marara; NIXO10; NOAA and MMS Marine Minerals Geochemical Database; NOAA-MMS; NX10-CL; Pacific Ocean; TECHNO 07  (3)
  • 1975-1979  (3)
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  • Data  (3)
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  • 1975-1979  (3)
Year
  • 1
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    Unknown
    Radionuclides in Manganese nodules (1978)
    PANGAEA
    In:  Supplement to: Guichard, Francois; Reyss, Jean-Louis; Yokoyama, Y (1978): Growth rate of manganese nodule measured with 10Be and 26Al. Nature, 272(5649), 155-156, https://doi.org/10.1038/272155a0
    Details
    Publication Date: 2023-08-28
    Description: Manganese nodules are considered to have accumulated in general very slowly: surface layers of nodules contain a large excess of 230Th, more than would be produced by uranium decay. The decrease of excess 230Th with depth within a nodule is generally interpreted to be due to the radioactive decay, and nodule accumulation rates were then estimated from this to be a few mm/Myr. How then do these nodules escape from burial by associated marine sediments which accumulate 3 orders of magnitude faster than the nodules? One possible explanation is that the radionuclides of interest were not incorporated in the nodule matrix during its growth but were adsorbed later. Subsequent inward diffusion of the radionuclides might result in an apparent radioactive decay. We have tested this hypothesis by measuring simultaneously two radionuclides of different half lives. If the gradients of the radionuclides are really due to the radioactive decay, then, assuming a constant growth rate for a nodule, we expect the profile of the shortlived nuclide to be steeper (because of its faster decay) than that of the longlived nuclide.
    Keywords: Dredge; DRG; Marara; NIXO10; NOAA and MMS Marine Minerals Geochemical Database; NOAA-MMS; NX10-CL; Pacific Ocean; TECHNO 07
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Expected Availability
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    DATA PANGAEA
  • 2
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    Unknown
    TECHNO encrustation description and analysis (1979)
    PANGAEA
    In:  Supplement to: Lalou, Claude; Ku, Teh-Lung; Brichet, Evelyne; Poupeau, G; Romary, P (1979): TECHNO encrustation, Part I: Radiometric studies. In: Lalou C. & Sorensen, B.M. (Eds), La Genèse Des Nodules de Manganèse. Centre Océanologique de Bretagne, Gif-sur-Yvette, France, 261-269, hdl:10013/epic.46220.d031
    Details
    Publication Date: 2023-08-28
    Description: The distribution of radioactivities in a large polymetallic encrustation (TECHNO) sampled from the Pacific sea floor has been studied in great detail. The study includes measurements of the long-lived U and Th decay series isotopes, alpha-particle tracks and SUP-10 Be and SUP-26 Al (Results on the latter two cosmonuclides have been reported by Guichard, Reyss and Yokoyama, 1978). The data are discussed in terms of their implication on age dating of the sample. Two interpretations of the data are presented leading to vastly different time scales for the formation of the sample. Here the opinion is divided among the authorship. One group, as well as Guichard et al (1978), favours the million-years scale and the other favors scale measured in thousands of years. The principal pros-and-cons aspects of the two views are mentioned.
    Keywords: Dredge; DRG; Marara; NIXO10; NOAA and MMS Marine Minerals Geochemical Database; NOAA-MMS; NX10-CL; Pacific Ocean; TECHNO 07
    Type: Dataset
    Format: application/zip, 4 datasets
    Location Call Number Expected Availability
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    DATA PANGAEA
  • 3
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    Unknown
    Structure and chemistry of TECHNO encrustations (1979)
    PANGAEA
    In:  Supplement to: Lalou, Claude; Brichet, Evelyne; Jehanno, Celestine (1979): TECHNO encrustation, Part II: Structural and Chemical study. In: Lalou C. & Sorensen, B.M. (Eds), La Genèse des Nodules de Manganèse. Centre Océanologique de Bretagne, Gif-sur-Yvette, France, 271-280, hdl:10013/epic.46220.d032
    Details
    Publication Date: 2023-08-28
    Description: Using as a starting point the results giving 'traditional' growth rates as determined by the decrease of radioelements (part I) and the hypothesis of rapid formation, the different mineralogical, structure and chemical characteristics of the sample have been studied to try to understand the possible mode of formation of this encrustation. A rapid formation would account for (1) the very peculiar structure of the sample composed of oriented botryoids and the bundle-like structure of the outermost oxide layer; (2) the fact that this sample represents a substitution of a preexisting hyaloclastite; (3) the different chemical gradients, mainly iron, thorium and uranium; (4) the fact that this sample which cannot have been maintained at the sediment-water interface by bioturbation is not covered by a great thickness of sediments. On the other hand, an unsolved problem remains: Why different radionuclides used for dating give growth rates of the same order of magnitude and different 'exposition ages'.
    Keywords: Dredge; DRG; Marara; NIXO10; NOAA and MMS Marine Minerals Geochemical Database; NOAA-MMS; NX10-CL; Pacific Ocean; TECHNO 07
    Type: Dataset
    Format: application/zip, 2 datasets
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    DATA PANGAEA
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