GEOCHEMICAL JOURNAL
Online ISSN : 1880-5973
Print ISSN : 0016-7002
ISSN-L : 0016-7002
18 巻 , 6 号
選択された号の論文の6件中1~6を表示しています
  • Ian M. Lange, H. Roy Krouse
    1984 年 18 巻 6 号 p. 269-280
    発行日: 1984/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    Sulfur isotopic analyses on vein pyrite and associated sulfides in a short section of a vein in the Intermediate Zone, Butte, Montana, show remarkable isotopic uniformity. The standard deviation (0.5 ‰) and range of pyrite values (1.4 to 3.9 ‰) are attributed to ore formation in a fO2-pH regime where the isotopic composition was insensitive to large changes in the physico-chemical conditions. The δ34S of the hydrothermal solution responsible for pyrite deposition is estimated to be +3.1 ‰. Large per mil differences and textural relationships between pyrites and associated copper and zinc sulfides show that the different sulfides were not deposited simultaneously and/or in isotopic equilibrium. Disseminated wall rock pyrites are depleted in 34S by as much as 2.4 ‰ relative to the adjacent vein and veinlets. The isotopic relationship between vein and disseminated pyrites may be due to a number of phenomena including diffusional fractionation, the effects of wall rock on the physico-chemical properties of the solution but are probably largely due to the interaction of pre-Main Stage and Main Stage hydrothermal processes. Delineation of these mechanisms is confounded by the presence of many veinlets in the wall rock.
  • Akira Shimoyama, Kaoru Harada
    1984 年 18 巻 6 号 p. 281-286
    発行日: 1984/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    Amino acids found in two carbonaceous chondrites (C2) from Antarctica, namely the Yamato-793321 and the Belgica-7904, were at the level of sub-namo moles per gram sample. These quantities are very small for C2 chondrites. The carbon and nitrogen contents of these two meteorites were suitable for C2 chondrites and, therefore, those two chondrites were unusually depleted in amino acids. This finding is new and there are two plausible explanations for the depletion. One is low temperature and/or aqueous metamorphisms of the two meteorites on their parent bodies, and the other is leaching of water extractable portions of the two meteorites by Antarctic water.
  • Mitsuru Ebihara, Yuji Nakamura, Hiroshi Wakita, Hajime Kurasawa, Tadas ...
    1984 年 18 巻 6 号 p. 287-295
    発行日: 1984/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    Abundances of trace elements including rare earth elements (REE) were determined by instrumental neutron activation analysis for twenty three Tertiary volcanic rocks of northeast Japan. Positive correlations were confirmed in the following couples of elements: Hf-La, K-La, Th-La and Fe-Sc. Unlike Quaternary volcanic rocks, Tertiary volcanic rocks show no definite correlation between the inclination of REE patterns and the distance of sampling sites from the estimated volcanic front of the Tertiary. The presence of low alkali tholeiites with relatively flat REE patterns in the Japan Sea side suggests that Tertiary volcanism is qualitatively different from Quaternary one.
  • C. Fouillac, A. Criaud
    1984 年 18 巻 6 号 p. 297-303
    発行日: 1984/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    The anions HCO3- and CO32- could play a major complexing role for trace metals in CO2 rich thermomineral water. The aim of this paper is to provide a complete thermochemical data set concerning the aqueous complexes of some divalent metal complexes (Fe, Mn, Ni, Co, Cu, Pb, Zn, Cd) with the ligands HCO3- and CO32-. When not previously determined experimentally, stability constants and enthalpies of formation of the complexes were estimated at 25°C from empirical correlations or theoretical approaches. The distribution of the trace metal species in typical water samples is given, indicating that the importance of complexes with bicarbonate cannot be neglected in that type of water.
  • Yoshiyuki Tatsumi, Shun Nakano
    1984 年 18 巻 6 号 p. 305-314
    発行日: 1984/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    K/Hf ratios of rocks from 39 Quaternary volcanoes in NE Japan have been examined. In most volcanoes, the ratio remains constant throughout the process of magmatic differentiation, suggesting that the ratios in volcanic rocks represent those in primary magmas produced in the upper mantle. The observed lateral variation of the ratios, increasing toward the back-arc side could be influenced by two factors. The first possibility could be the result of systematic differences in the degree of partial melting, decreasing toward the back-arc side, during which process minor minerals such as zircon, sphene, perovskite, and rutile buffer the concentration of Hf in the liquid produced; the second possibility is the result of differences in K/Hf ratios of fluid phases added to the mantle wedge from the downgoing lithosphere in which serpentine and phlogopite decompose beneath fore- and back-arc regions, respectively.
  • Hisayuki Inoue, Yukio Sugimura
    1984 年 18 巻 6 号 p. 315-320
    発行日: 1984/12/20
    公開日: 2008/04/08
    ジャーナル フリー
    In September 1982 and June 1983, diurnal variations in the 13C/12C ratio and concentration of atmospheric CO2 were studied. The concentration and δ13C value of CO2 turn to be maximum just before dawn and minimum during daytime. This dirnal variations are caused through the simple mixing of two different isotopic CO2 species, which are CO2 in the ambient air and CO2 from biosphere. The carbon isotopic ratio of CO2 derived from biosphere is estimated to be -22 to -23‰ with respect to PDB standard. The estimated value is a little higher than the δ13C value attributed to the plant respiration. According to the observed δ13C value in soil air ranging from -11 to -16‰, the little higher value may be explainable as a consequence of addition of soil air CO2 into the surface air.
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