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Volume 5 (1971)
- Issue 4 Pages 151-
- Issue 3 Pages 113-
- Issue 2 Pages 57-
- Issue 1 Pages 1-
Volume 5, Issue 3
Displaying 1-3 of 3 articles from this issue
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Ichiro Kaneoka1971 Volume 5 Issue 3 Pages 113-120
Published: 1971
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSThe ages of, submarine rocks dredged from seamounts along the Japan Trench were determined by K-Ar method. In order to obtain more reliable age, the effect of acid leaching on an altered submarine rock was examined. Some samples treated by acid solution gave K-Ar ages up to 20% older than the original untreated sample. This result suggests a possibility that, if suitable acid teratment conditions are found, they would result in more reliable ages for submarine rocks. Some submarine rocks dredged from seamounts along the Japan Trench on the oceanic side gave K-Ar ages of about 70-80 m.y, whereas a sample dredged from a seamount on the Japanese Islands side gave a substantially younger age. Considering the present result as well as previous data, the last volcanic activity along the Japan Trench seems to have occurred about 70-80 m.y ago or older.View full abstractDownload PDF (3550K) -
Ryoshi Ishiwatari1971 Volume 5 Issue 3 Pages 121-132
Published: 1971
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSMolecular weights of humic acids separated from two lake and three marine sediments were measured by gel filtration through Sephadexes. The results indicate that mol. wt. of humic acid distributes from less than 700 to over 200, 000. On the basis of mol. wt. the humic acids are divided into three main groups: (1) components with mol. wt. from 100, 000 to over 200, 000 (43-70%), (2) components with mol. wt. from 5, 000 to 10, 000 (8-25%) and (3) components with mol. wt. less than 700 (10-17%). The humic acids gave rise to lower mol. wt. compounds on acid or alkali hydrolysis, but the ratio of the hydrolyzable portion to the total varied from sample to sample. A possible conversion process of sedimentary humic acids is discussed.View full abstractDownload PDF (5467K) -
Yoshimichi Kajiwara, Jiro Date1971 Volume 5 Issue 3 Pages 133-150
Published: 1971
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSSulfur isotope data of sulfide and sulfate minerals from the Kuroko-type deposits of the Miocene age (63 samples of mill concentrates and 48 separate specimens) and from the later Paleozoic so-called Kieslager-type deposits (20 samples of mill concentrates and 11 separate specimens) are reported. The data of sulfides from the Kuroko-type deposits can be divided into two groups, i.e., a lower δ34S group of which deposits in the Ohdate area are representative and a higher δ34S group characterized by deposits in the Kosaka district. A remarkable difference between the Kuroko-type and the Kieslager-type is that the average sulfur isotopic fractionation factor between sulfides and contemporaneous sea-water sulfate is slightly larger in the Kuroko-type deposits than in the Kieslarger-type deposits. Based on the same logic as developed in the previous paper (KAJIWARA, 1971), the difference between the two groups of the Kuroko-type deposits as well as between the Kuroko-type deposits and the Kieslager-type deposits is most likely due to the difference in oxidation state at the time of their deposition, the first mentioned of each pair being higher in oxygen fugacity of ore formation. Similarly, it is also concluded that the “volcanic type” deposits of SANGSTER (1968) are relatively higher in the depositional oxidation state than the “sedimentary type” deposits.View full abstractDownload PDF (8540K)
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