巻号一覧
2 巻 (1968)
- 3-4 号 p. 111-
- 2 号 p. 61-
- 1 号 p. 1-
2 巻, 1 号
選択された号の論文の4件中1～4を表示しています
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Fumihiro Honda, Yoshihiko Mizutani1968 年 2 巻 1 号 p. 1-9
発行日: 1968年
公開日: 2008/04/08
ジャーナル フリーA siliceous sublimate, collected from an active fumarole of Kuju Volcano, was analyzed for major constituents. The water soluble fraction of the sublimate contains large quantities of halogen acids and silicon, and the insoluble fraction consists of hydrated silica with a trace amount of native sulfur. In order to ascertain the presence of gaseous silicon compounds in fumarolic gases, condensate samples were collected from high temperature fumaroles of Kuju and Nasudake Volcanoes with a silica-free sampling device. The silicon and fluorine contents of fumarolic gases range from 1 to 52 mg Si/kg H2O and 1 to 320 mg F/kg H2O, respectively. Silicon is transported probably as fluoride in fumarolic gases, and the sublimate is formed by hydrolysis of silicon fluoride when the gas temperature falls to the boiling point of water.抄録全体を表示PDF形式でダウンロード (3934K) -
Hajime Kurasawa1968 年 2 巻 1 号 p. 11-28
発行日: 1968年
公開日: 2008/04/08
ジャーナル フリーThe isotopic composition of lead and the abundances of lead, uranium, and thorium in alkali rocks from Dogo of the Oki Islands, and Taka-shima, West Japan, have been determined. The lead, uranium and thorium contents range from 2.4 to 21.7 ppm, 0.4 to 3.6 ppm, and 2.6 to 27.1 ppm, respectively. They show a slight increase with progress in magmatic differentiation and a large increase from trachyte to rhyolite. A range of μ0 (238U/204Pb) = 8.6∼8.7 is calculated for a primary growth curve from the leads of Dogo. The observed μ (238U/204Pb) values of the rocks fall in a range 8.4∼13.5. The observed κ (232Th/238U) values are in a range 4.8∼9.8. The observed μ and κ for the rocks of Dogo are higher than for tholeiites and highalumina basalts in Japan. The rocks from Dogo are relatively deficient in 206Pb compared with the calculated model, suggesting that at least some lead was derived from a source of low μ during the last 2∼3 b.y. Consequently these volcanic rocks show isochron model ages of around 0∼500 m.y., which are older than the known age of the rocks. In addition, olivine basalts are isotopically uniform and more radiogenic in 206Pb/204Pb than the trachybasalt and the alkali series differentiates. Either the trachybasalts were generated from a source different from the rest of the volcanic rocks or, if all the volcanic rocks were generated from a single source, they subsequently acquired some leads isotopically different from those of the source. Natural contamination can explain the peculiar results in the islands, where partial assimilation of pre-Tertiary basement rocks, probably Precambrian rocks resulted in the less radiogenic lead isotope ratios in the differentiates from the islands.抄録全体を表示PDF形式でダウンロード (8865K) -
Hitoshi Sakai1968 年 2 巻 1 号 p. 29-49
発行日: 1968年
公開日: 2008/04/08
ジャーナル フリーThe reduced partition function ratio predicts that among sulfide minerals in isotopic equilibria the heavy isotope (34S) is enriched in the following order: galena < chalcopyrite < sphalerite < pyrite. This order also exists among coexisting sulfides in natural deposits. The isotopic composition of pyrite at hydrothermal temperatures is estimated to be very close to that of gaseous hydrogen sulfide. The isotopic property of aqueous sulfide ions is determined by the relative concentrations of the three species H2S, HS-, and S2-, all of which have different reduced partition function ratios. Therefore, the pH of hydrothermal solution is as important a parameter as the temperature in determining the isotopic ratio of a sulfide mineral. δS* of pyrite, for instance, in isotopic equilibrium with a solution at 500°K having a δS of 0.0‰, would be +5.0‰ at pH 9.5, +2.0‰ at pH 8.0, and 0.0‰ at pH 4.0. Some natural examples are discussed which may indicate a change with time in the pH as well as in the isotopic raito of hydrothermal solutions during mineralization. The isotopic exchange reaction between sulfide and sulfate is also discussed.抄録全体を表示PDF形式でダウンロード (10792K) -
Yoshito Matsui, Yasuhiko Syono1968 年 2 巻 1 号 p. 51-59
発行日: 1968年
公開日: 2008/04/08
ジャーナル フリーTwo series of solid solutions of olivine structure, (Mg, Co)2SiO4 and (Mg, Ni)2SiO4, were synthesized at 1, 400°C, and their unit cell parameters were measured at room temperature. It was found that deviations from Vegard's law increase according to the order (Mg, Fe)2SiO4, (Mg, Co)2SiO4 and (Mg, Ni)2SiO4. This order coincides with the order of octahedral crystal field stabilization energies of transition metal ions. It was suggested that the site preference of Mg and transition metal ions over MI and MII sites is most pronounced in the case of (Mg, Ni)2SiO4 solid solution series.抄録全体を表示PDF形式でダウンロード (3946K)
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