GEOCHEMICAL JOURNAL
Online ISSN : 1880-5973
Print ISSN : 0016-7002
ISSN-L : 0016-7002
10 巻 , 2 号
選択された号の論文の8件中1~8を表示しています
  • L. H. Ahrens
    1976 年 10 巻 2 号 p. 51-58
    発行日: 1976/06/20
    公開日: 2008/04/08
    ジャーナル フリー
    The Cr distribution and the Cr-Mg relationship in terrestrial, meteoritic and lunar basalts have been examined. Meteoritic and lunar basalts contain on average, approximately the same amount of Cr which is an order of magnitude greater than that for terrestrial basalts. On the other hand, the statistical nature of the Cr distribution in each of the three sets of basalts differs distinctly. Cr and Mg correlate positively in meteoritic basalts and define a near-perfect straight line trend. Cr and Mg are also positively correlated in lunar basalts but with a much greater spread of values. The Cr-Mg meteorite line approximately bisects the spread of points of lunar basalts. Each Apollo mission site has a characteristic Cr-Mg relationship. An attempt by means of ionization potentials to predict the likelihood of CrII on the lunar surface has been inconclusive.
  • Keisuke Ito
    1976 年 10 巻 2 号 p. 59-64
    発行日: 1976/06/20
    公開日: 2008/04/08
    ジャーナル フリー
    A hypothesis is proposed that outer cores of the terrestrial planets consist of a eutectic melt between the inner core iron and the lower mantle oxide. MgO, a major consituent of the lower mantle, is estimated to be substantially soluble in iron melt at high pressures and high temperatures reached in the outer core. Mars does not have an outer core, and Venus has a much smaller outer core than the Earth. On an assumption that the overall chemistry (Fe/Oxide ratio) is the same among the terrestrial planets except Mercury, or an alternative assumption that the metallic-iron/total-mass ratio increases in the decreasing order of distance from the sun, from 0.20 for Mars to 0.25 for Earth and Venus, the eutectic composition is estimated to be 0.41 by the first assumption or 0.24 by the second one. The Earth, when it was hotter, did not have a solid inner core. When it cooled, iron and oxide coprecipitated from the eutectic melt, iron sank to form the inner core, and oxide floated to form the D'' region.
  • P. K. Kuroda
    1976 年 10 巻 2 号 p. 65-70
    発行日: 1976/06/20
    公開日: 2008/04/08
    ジャーナル フリー
    The difference in the xenon-iodine formation intervals for the magnetite samples from the carbonaceous chondrites Orgueil, Murchison and Karoonda is less than 0.7 million years and the chondrites Bjurböle and Arapahoe began to retain xenon a few million years after the magnetites. The isotopic composition of the trapped xenon in these meteorites is identical to that of the carbonaceous chondrite Murray.
  • C. B. Dissanayake
    1976 年 10 巻 2 号 p. 71-78
    発行日: 1976/06/20
    公開日: 2008/04/08
    ジャーナル フリー
    The bismuth contents of 19 rocks from the Skaergaard intrusion, determined by a sub-stoichiometric tracer isotope dilution method, range from 0.01 to 0.60 ppm. The chilled margnal gabbro contains 0.05 ppm Bi; the average bismuth content of the 7 analysed Lower Zone rocks from the Layered Series is 0.09ppm; of the 3 analysed (olivine-free) Middle Zone rocks 0.24ppm; of the 5 analysed ferrodiorites from the Upper Zone 0.26ppm. A melanogranophyre from the Upper Border Group contains 0.23 ppm, and two acid granophyres 0.24 and 0.60 ppm. Analysis for bismuth of separated cumulus minerals from 5 Layered Series rocks shows that about 70% of the total amount of the element found in a rock is present in the cumulus phases, the remainder in the mesostasis derived from the residual magmatic liquids. While bismuth is not particularly sharply distributed between the cumulus phases, titaniferous magnetite and ilmenite provide the most favourable host minerals, followed by olivine, while pyroxene and plagioclase contain lesser amounts. Bi3+ would appear mainly to substitute for Fe2+ in the oxides and ferromagnesian silicates. There is little evidence either of any Bi3+-Ca2+ coherence, or of any tendency for bismuth to become enriched in the accessory sulphide minerals of the intrusion.
  • Noboru Nakamura, Akimasa Masuda
    1976 年 10 巻 2 号 p. 79-83
    発行日: 1976/06/20
    公開日: 2008/04/08
    ジャーナル フリー
    Major elements Mg, Ca, Fe, Mn, K and Al were determined for the natural silicate system, for which the partition coefficients of REE, Ba and Sr were obtained by TANAKA and NISHIZAWA (1975). The regular aspects of variation in concentrations of elements for three runs of 20kb experiment are discussed. Also it is shown that the formed mineral is aluminous clinopyroxene and that the REE partition coefficients appear to have some bearing on Al2O3 content of the formed solid phase. Discussions are given to implications of exceedingly high values of apparent partition coefficients for some trace elements in this experiment.
  • H. Sakai, J. W. Smith, I. R. Kaplan, C. Petrowski
    1976 年 10 巻 2 号 p. 85-96
    発行日: 1976/06/20
    公開日: 2008/04/08
    ジャーナル フリー
    Pyrolysis-combustion, direct combustion and hydrolysis procedures have been developed for study of returned lunar samples. These procedures are also applicable to the analysis of numerous elements on relatively small geological specimens. During pyrolysis-combustion, the sample is degassed at 150°C, heated in vacuum to 1, 225°C and the various gaseous products are measured and collected. Then, the pyrolysis residue is combusted in a partial atmosphere of oxygen and additional gaseous products are collected. The above method allows the following measurements: C (as CO2, CH4 and CO); total H, total He, total N, combusted C, δ13CPDB and δ15Nair. By direct combustion in oxygen, the abundances of C, S, N and He, as well as δ13CPDB, δ15Nair and δ34SCD are determined. Hydrolysis involves reacting the sample in 6N H2SO4 overnight at 105°C. The gaseous products collected and measured are: S (as H2S), δ34SCD, acid hydrolyzable CH4, He and % metallic Fe (from H2 released). Standards were analyzed to demonstrate the capabilities and reliabilities of the different experiments. A suite of lunar samples was studied using these new techniques. Replicate and duplicate analyses of these samples and a comparison with literature values obtained by different methods show a high degree of confidence which can be placed in the techniques described.
  • Tadashiro Koyama
    1976 年 10 巻 2 号 p. 97-102
    発行日: 1976/06/20
    公開日: 2008/04/08
    ジャーナル フリー
    Core samples were collected from Lake Suwa and Lake Kizaki in Nagano Prefecture, Japan. They were divided into several pieces at 2 or 15cm intervals. Each of them was taken in a soil injector and incubated at 26-27°C for about 40 days. The production of CH4 in the surface sediments amounts to about 200ml/100g of dry sediment and markedly decreases toward 20cm core depth to about 20ml/100g. In sediments deeper than 20cm, the production of CH4 gradually decreases to nearly zero at a depth of about 60cm. The vertical profile of the CH4 production is similar to those of various organic components. The methane production in the core samples from 50 to 100cm, mixed with sodium acetate corresponds to about 70% of what is theoretically expected from the amount of sodium acetate added. For samples from 100 to 140cm, however, it decreases on a straight line to zero. This seems to reveal that the decrease in CH4 production for deeper parts of the core samples is not only caused by the decrease in the substrates for methane fermentation but also by the decrease in microbiological activities for methane fermentation resulting in gradual disappearance from 100cm toward 140cm core depth.
  • Yu. A. Balashov, A. I. Tugarinov
    1976 年 10 巻 2 号 p. 103-106
    発行日: 1976/06/20
    公開日: 2008/04/08
    ジャーナル フリー
    In accordance with the average RE content of sedimentary and magmatic rocks the abundance of RE in the Earth's crust is estimated as being close to 100∼110ppm. The evolution of RE composition and content of the sedimentary cover of the continents (in particular the appearance of europium deficiency in young sediments) is conditioned by the influence of the material predominantly from acid magmas which are generated in the crust.
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