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Volume 8 (1974)
- Issue 4 Pages 157-
- Issue 3 Pages 109-
- Issue 2 Pages 47-
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Volume 8, Issue 4
Displaying 1-4 of 4 articles from this issue
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Naoko Ueno, Ichiro Kaneoka, Minoru Ozima1974 Volume 8 Issue 4 Pages 157-164
Published: 1974
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSOne granodiorite, two basalts and five andesites dredged from seamounts and banks in the Japan Sea were studied by means of K-Ar and Rb-Sr dating methods. The granodiorite gives a concordant age of 227m.y, while the ages of the basalts and andesites range from 4 to 22m.y. The Sr isotopic ratios (87Sr/86Sr)0 of these samples are higher than the mean for island basalts.View full abstractDownload PDF (3519K) -
Sadao Matsuo, Tetsuro Suzuoki, Minoru Kusakabe, Hiroaki Wada, Masaru S ...1974 Volume 8 Issue 4 Pages 165-173
Published: 1974
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSD/H and 18O/16O ratios of fumarolic condensate, hot spring water and surface water collected from a volcanic island, Satsuma-Iwojima were determined together with some of chemical components. δD and δ18O of fumarolic condensates range from -27 to -17‰ (SMOW) and from +7.3 to +9.5‰ (SMOW), respectively. The high value of δ18O was concluded to be the result of thorough oxygen isotope exchange with ambient andesitic rocks. δD values are also higher than that of the local surface water, but we could not find a positive evidence that supports the assumption of mixing of the local surface water and sea water. On the basis of the relationship between the concentration of chemical components and isotope ratios of fumarolic condensates, it was concluded that water vapor and chemical components behave independently in an individual fumarole.View full abstractDownload PDF (4251K) -
Atsushi Ando, Hajime Kurasawa, Teiko Ohmori, Eizo Takeda1974 Volume 8 Issue 4 Pages 175-192
Published: 1974
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSAnalytical data received by October, 1974 for rock analyses, 53 minor elements and strontium isotopic ratios of the GSJ JG-1 granodiorite and JB-1 basalt are tabulated: Averages for both major and minor elements are given.View full abstractDownload PDF (7168K) -
Ken Shibata1974 Volume 8 Issue 4 Pages 193-207
Published: 1974
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSWhole-rock samples of the Hikami granite from the southern Kitakami mountains in Northeast Japan give a Rb-Sr age of 339 ± 12m.y with an initial 87Sr/86Sr ratio of 0.7079 ± 0.0003, indicating that the granite intruded in the late Devonian to early Carboniferous time. A slightly high initial 87Sr/86Sr ratio for the Hikami granite suggests that the granite assimilated some amount of older crust. The Tsubonosawa gneiss, which is contained in the Hikami granite as xenolithic masses, gives an isochron age of 334m.y with an initial 87Sr/86Sr ratio of 0.7129. The results show that the Sr isotopic homogenization occurred among the whole masses of the gneiss at the time of granite intrusion. A higher initial 87Sr/86Sr ratio suggests that the gneiss originated in the Precambrian time. Granite boulders from the Devonian Ono formation do not define any isochron, whereas the sandstone from the Silurian Kawauchi formation gives an apparent age of 264m.y. The whole-rock systems of boulders and sandstone may have remained open with respect to Rb and Sr, probably because of their involvement in sedimentary process. The Rb-Sr isotopic data for the Cretaceous Tono and Kesengawa granites confirm the evidence that almost all igneous rocks in Northeast Japan, irrespective of age, have low initial 87Sr/86Sr ratios, reflecting a distinctive nature of crust in Northeast Japan.View full abstractDownload PDF (7160K)
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