GEOCHEMICAL JOURNAL
Online ISSN : 1880-5973
Print ISSN : 0016-7002
ISSN-L : 0016-7002
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Volume 4, Issue 1
Displaying 1-4 of 4 articles from this issue
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  • Some geochemical characteristics of recent glacial sediments
    David C. Burrell, Neal R. O'Brien
    1970 Volume 4 Issue 1 Pages 1-13
    Published: 1970
    Released on J-STAGE: April 08, 2008
    DOIhttps://doi.org/10.2343/geochemj.4.1
    JOURNAL FREE ACCESS
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    Mineralogical studies of recent glacial sediments within an active glacial fiord have shown distinctive sub-arctic characteristics and remarkable uniformity both over wide areas and with depth. Such sediments are thus most suitable for the study of pore water-sediment relationships. For the major cations, the ion exchange capacity of the coexisting sediment is shown to be the principal parameter controlling the composition of the interstitial water, and these ions demonstrate some different exchange features at depth compared with surface samples. Trace metal concentrations appear to be unrelated to the major ions of the various phases. The proposed relationships are shown for a representative piston core profile.
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  • Mössbauer study of synthetic calcium-rich pyroxenes
    Yoshito Matsui, Yonezo Maeda, Yasuhiko Syono
    1970 Volume 4 Issue 1 Pages 15-26
    Published: 1970
    Released on J-STAGE: April 08, 2008
    DOIhttps://doi.org/10.2343/geochemj.4.15
    JOURNAL FREE ACCESS
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    In the calcium-rich pyroxenes Fe2+ ion in the M1 positions gives rise to the inner Mössbauer doublet, and Fe2+ in M2 to the outer doublet. The Fe2+-Mg order over the M1 and M2 positions was found unexpectedly weak, being close to the complete disorder at about 1, 200°C. A four-line spectrum was observed in Di50Hd50 prepared by usual sintering technique at 1, 150°C. This may be due to the local disorder of Fe2+ and Ca. The disordered configuration seems to be metastable, and the reaction towards the ordered structure to be extremely sluggish.
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  • Sulfur and oxygen isotopic geochemistry of sulfate in the black ore deposits of Japan
    Hitoshi Sakai, Susumu Osaki, Masanobu Tsukagishi
    1970 Volume 4 Issue 1 Pages 27-39
    Published: 1970
    Released on J-STAGE: April 08, 2008
    DOIhttps://doi.org/10.2343/geochemj.4.27
    JOURNAL FREE ACCESS
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    The sulfur isotopic values of barite, gypsum and anhydrite from the typical strata-bound submarine ore deposits (black ore deposits) of Miocene age in Japan have a narrow range of +21 to 24‰ with respect to the meteoritic sulfur. However, the oxygen isotopic values (in SMOW) vary from +5 to +19‰ and have a general tendency to increase in the order: barite < anhydrite ≈ alabaster < secondary gypsum (satin spar and selenite). The sulfate minerals from the late Paleozoic cupriferrous iron sulfide ore deposits of the Yanahara and Besshi mines are similar in the sulfur isotopic values (+11 to +15‰) to inferred Permian sea water sulfate, whereas the oxygen isotopic values have a wide range of variation. The observed sulfur isotopic pattern is most Likely due to a submarine hydrothermal system in which sulfate of marine origin (connate or actual sea water) predominated over other sources of sulfur. The variable oxygen isotopic data of sulfate are explained by the oxygen isotopic exchange between sulfate and water during depositional and post-depositional processes. The sulfur and oxygen isotopic ratios of “hot sulfate” in the Wairakei and the Red Sea geothermal brines are consistent with this idea. The sulfates in secondary gypsum ores in the Noto mine are enriched in both 34S and 18O, suggesting that the alteration of the primary ores in this mine may have taken place under the influence of sulfate-reducing bacteria.
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  • Seawater sulfate as a possible determinant for sulfur isotopic compositions of some strata-bound sulfide ores
    Akira Sasaki
    1970 Volume 4 Issue 1 Pages 41-51
    Published: 1970
    Released on J-STAGE: April 08, 2008
    DOIhttps://doi.org/10.2343/geochemj.4.41
    JOURNAL FREE ACCESS
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    If some of the strata-bound sulfide ores result from deposition on the seafloor through submarine volcanic activity, it seems probable that the isotopic exchange reaction takes place between seawater sulfate and volcanically derived sulfur compounds, at least to some extent. Since the amount of sulfur from seawater would normally be much larger than that from volcanic source, it is expected that the isotopic compositions of sulfur-bearing species in this system are largely controlled by the seawater sulfate. A remarkable parallelism observed between sulfur isotopic compositions of ancient seawater sulfate and the strata-bound sulfide deposits of volcanic association throughout geologic time (SANGSTER, 1968) may most reasonably be explained with this hypothesis.
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