GEOCHEMICAL JOURNAL
Online ISSN : 1880-5973
Print ISSN : 0016-7002
ISSN-L : 0016-7002
13 巻 , 2 号
選択された号の論文の5件中1~5を表示しています
  • John M. Bird, Maura S. Weathers
    1979 年 13 巻 2 号 p. 41-55
    発行日: 1979/04/20
    公開日: 2008/04/08
    ジャーナル フリー
    Josephinite is a nickel-iron alloy-bearing rock from Josephine County, southwestern Oregon. Josephinite had been thought to be the same as the metallic nickel-iron mineral awaruite (KRISHNARAO, 1962, 1964; RAMDOHR, 1950), but recently it has been shown to be a complex assemblage of minerals (BIRD and WEATHERS, 1975a). Although most samples of josephinite are somewhat altered, least-altered josephinite consists of several nickel-iron alloys, one intergrown with andradite garnet, an iron-cobalt alloy, and minor amounts of iron-nickel arsenides, iron-nickel-copper sulphides, and various unidentified phases. The intergrown metal-garent assemblage is apparently unique to josephinite. Alteration phases include serpentine minerals and magnetite. Josephinite occurs as detritus in several streams that originate and flow on the Josephine Peridotite; bedrock includes sheared serpentinite zones and basaltic to dioritic dikes within the peridotite. It is a reasonable assumption that the josephinite pebbles must be associated with one or more of these rocks; however, no unequivocal, large josephinite samples have been found within bedrock. BIRD and WEATHERS (1975a) proposed that because of its remarkable and apparently unique composition and textures, and its association with obducted mantle, josephinite has been derived from the mantle, conceivably the deep-mantle. Subsequently, DICK (1974), THORNBER and HAGGERTY (1976) and BOTTO and MORRISON (1976), following RAMDOHR (1950), argued that josephinite was formed by reduction of silicates, or sulphides, during serpentinization of the Josephine Peridotite. Currently, there are two views concerning the origin of josephinite: 1) josephinite is a product of low-temperature, synserpentinization processes and is comparable with awaruite 2) because of its mineral composition, textures, and rock associations, josephinite pre-dated serpentinization of the Josephine Peridotite (obducted ophiolite), was related to the origin of the Josephine Peridotite, and was derived from the primitive mantle, conceivably from as deep as the core-mantle boundary. Excesses of 3He, 21Ne and 129Xe have recently been found in josephinite and have been interpreted to indicate a mantle residence and, perhaps, a primordial age for this rock (DOWNING et al., 1977; BOCHSLER et al., 1978). We continue to propose a mantle derivation of josephinite; additionally, we suggest that josephinite was primitive material incorporated into the earth during earth accretion.
  • Iwao Kawabe
    1979 年 13 巻 2 号 p. 57-67
    発行日: 1979/04/20
    公開日: 2008/04/08
    ジャーナル フリー
    A full lattice dynamical method has been applied to the calculation of the oxygen isotopic partition function ratio for α-quartz in order to examine the result of the Debye-Einstein model calculation. The modified Urey-Bradley force field was used as a force field model of α-quartz. The phonon dispersion curves and elastic constants of α-quartz have also been calculated. These calculated values are in fairly good agreement with the available experimental data. The agreement gives additional grounds for the use of the modified Urey-Bradley force field. The wave vector-dependence of Infqtz(q) has been examined along the x, y, and z directions in the Brillouin zone. It has been found that the Infqtz(q) little changes with the wave vector. The changes of the Infqtz(q) along the three directions are only less than 0.5% at 0°C, although the value of Infqtz(q) becomes a minimum at the Brillouin zone center. By virtue of the small wave-vector dependence of Inqtz(q), the reduced partition function ratio for α-quartz given by the direct summation technique converges very rapidly. The reduced partition function ratio for α-quartz has been evaluated in the temperature range between 0 and 550°C by means of the direct summation technique combined with the perturbation method. The obtained values of the oxygen isotope fractionation factor between α-quartz and liquid water below 100°C can be expressed as 103Inαqtz-H2O(1) = -17.287+8.6913(103/T) + 1.8459(103/T)2. This temperature scale gives only 1-1.5 ‰ higher fractionations than that of the earlier Debye-Einstein model calculation. When the small differences of the fractionations between the present and earlier calculations and the error associated with the theoretical calculation are taken into consideration, the Debye-Einstein approximation in evaluating the isotopic partition function ratio for α-quartz can be concluded not to bias seriously the result.
  • Michel Loubet, Claude J. Allegre
    1979 年 13 巻 2 号 p. 69-75
    発行日: 1979/04/20
    公開日: 2008/04/08
    ジャーナル フリー
    The content of rare earth and transition elements has been analysed in Beni-Bouchera orogenic peridotites. Results suggest that lherzolite - the predominant petrographic type - is of residual nature while pyroxenite layers represent the product of multiple melting episodes.
  • Yasushi Kitano, Ryoko Fujiyoshi
    1979 年 13 巻 2 号 p. 77-81
    発行日: 1979/04/20
    公開日: 2008/04/08
    ジャーナル フリー
    The distribution of cadmium between calcium phosphate and solution has been investigated, when calcium phosphate is precipitated from calcium nitrate, diammonium hydrogen phosphate and cadmium nitrate solutions containing sodium chloride (0, 0.53 mol/l) or magnesium chloride (0, 5.0 × 10-2mol/l) at 25 and 100°C: Cadmium in the parent solution is mostly incorporated in hydroxyapatite as a solid solution between hydroxyapatite and apatitic cadmium phosphate. Adsorption of cadmium on suspended hydroxyapatite has been also examined: It is greatly reduced by the presence of calcium ions in the solution.
  • P. K. Kuroda
    1979 年 13 巻 2 号 p. 83-90
    発行日: 1979/04/20
    公開日: 2008/04/08
    ジャーナル フリー
    Isotopic anomalies observed in meteorites for O, Mg, Ca, Xe, Ba, Nd and U can be attributed to a combined effect of mass fractionation, neutron capture and cosmic-ray irradiation processes which took place prior to and during the formation of the solar system. The total cosmic-ray neutron flux (time integrated) appears to have been such that the isotopic compositions of a number of elements were altered appreciably.
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