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Volume 6 (1972 - 1973･･･
- Issue 4 Pages 151-
- Issue 3 Pages 105-
- Issue 2 Pages 43-
- Issue 1 Pages 1-
Volume 6, Issue 4
Displaying 1-5 of 5 articles from this issue
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Susumu Osaki1973 Volume 6 Issue 4 Pages 151-162
Published: 1973
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSCarbon and oxygen isotope abundances were determined for hydrothermal rhodochrosites from Oe, Inakuraishi and Jokoku mines. The isotopic ratios of pale pink rhodochrosites from Oe and Inakuraishi are in the narrow ranges from -7.5 to -9.5‰ in δ13CPDB and 2.0 to 7.0‰ in δ18OSMOW. δ18O values of compact brown rhodochrosites from Oe and of large red rhodochrosite crystals from Inakuraishi spread in a range higher than that of pale pink ones. The isotopic ratios of the Jokoku rhodochrosites are in the ranges from -2.5 to -7.5 ‰ in δ13C and from 7.0 to 15.0 ‰ in δ18O. Pale pink rhodochrosites from Oe and Inakuraishi were derived from homogeneous hydrothermal solutions which were probably meteoric in origin. Some amounts of compact brown rhodochrosites from Oe and of large red rhodochrosite crystals from Inakuraishi were precipitated possibly from remaining hydrothermal solutions which might have exchanged oxygen isotopes with host silicates. The higher δ13C and δ18O values of the Jokoku rhodochrosites are probably due to contamination with limestone. Homogeneous distribution of the isotopic ratios suggests that limestone was dissolved somewhere and the solution was brought to Jokoku mine.View full abstractDownload PDF (5312K) -
Susumu Osaki1973 Volume 6 Issue 4 Pages 163-177
Published: 1973
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSCarbon and oxygen isotope abundances were determined for dolomites and calcites in Tertiary (Ogi and Otobe) and Permian (Miyama and Kuzuu) dolostones in Japan. Isotopic ratios of calcites in some of Tertiary and Permian limestones in Japan were also determined for comparison. The isotopic ratios of Tertiary dolomites are extremely low in δ13C values, and depend on localities. Those of Permian dolomites are distributed in narrow ranges from 2 to 6‰ in δ13CPDB and from 23 to 30‰ in in δ18OSMOW. They do not seem to depend on their localities and their mineralogical and geological features. A considerable difference in isotopic ratios between Tertiary and Permian dolomites suggests that Tertiary dolomites differ from Permian dolomites with respect to the origin. Tertiary dolomites might have been precipitated primarily from sea water in anaerobic environments, possibly owing to rise of PCO2 by decarboxylation of organic materials. The isotopic ratios of Permian dolomites cannot be explained by the current theories on the origin of dolomite.View full abstractDownload PDF (6576K) -
Susumu Osaki1973 Volume 6 Issue 4 Pages 179-182
Published: 1973
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESS-The carbon and oxygen isotopic abundances were determined for calcites and dolomites filling gaps in the Ogi basalt. The isotopic ratios of the carbonates are in the range from -24 to -32 ‰ in δ13CPDB and from 31 to 36 ‰ in δ18OSMOW. They were too low in δ13C and too high in δ18O to understand that they were derived from carbonatite. The δ18O values are also too high to interpret that they were derived from basaltic magma. The isotopic data suggest that they were precipitated probably from lagoonal sea water under anaerobic conditions.View full abstractDownload PDF (1861K) -
Yoshihiko Mizutani, T. Athol Rafter1973 Volume 6 Issue 4 Pages 183-191
Published: 1973
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSThe oxygen isotopic ratio of the sulphate remaining in the bacterial sulphate reduction has been found to be dependent on the oxygen isotopic ratio of the water in which the sulphate was reduced by bacteria. This finding is interpreted by a mechanism, in which the sulphate exchanges oxygen isotopes with the water through the intermediates in the bacterial reduction of sulphate into sulphide.View full abstractDownload PDF (4037K) -
Yoshimichi Kajiwara1973 Volume 6 Issue 4 Pages 193-209
Published: 1973
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSOn the basis of a model chloride-complex solution with the same metallic abundances as the present-day oceanic water, the physicochemical factors controlling the ore-zoning observed in the Kuroko type mineralization in Japan have been examined. The result reveals that the ore-zoning can be explained by the oxidation and/or neutralization processes of the model ore-forming solution. This is in complete harmony with the interpretation expressed in the recent sulfur isotope studies of this type of mineralization. The hypothesis that the Kuroko ore-forming solution might have been derived essentially from the coeval seawater (KAJIWARA, 1973) appears to be acceptable. Extending the hypothesis, it is suggested that many of the hydrothermal systems in the earth's crust probably represent the circulating coeval seawaters. With this view, the natural hydrothermal mineralizations may be divided into two types, (A) mineralizations due to the reduction processes of the incorporated seawater and (B) those due to the oxidation processes of the once reduced circulating seawater. The deposits formed in shallow environments such as Kuroko and those formed in relatively deep environments such as contact metasomatic deposits may represent the oxidation- and the reduction-type mineralizations, respectively. It is also probable that the generation of silicate magmas in the orogenic belts is closely related to the availability of such circulating seawater in the earth's crust and possibly in the upper mantle.View full abstractDownload PDF (6223K)
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