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Volume 21 (1987)
- Issue 6 Pages 253-
- Issue 5 Pages 197-
- Issue 4 Pages 139-
- Issue 3 Pages 85-
- Issue 2 Pages 43-
- Issue 1 Pages 1-
Volume 21, Issue 3
Displaying 1-5 of 5 articles from this issue
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Hisayoshi Yurimoto, Shigeho Sueno1987 Volume 21 Issue 3 Pages 85-104
Published: 1987
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSPartition coefficients for -1, -2, -3, +1, +2, +3, +4 and +5 valent ions between the groundmass of boninite and coexisting phenocrysts, bronizite, protoenstatite, augite and chrome spinel, from Bonin Island, Japan have been determined by secondary ion mass spectrometry (SIMS). The SIMS method could reveal the equilibria between the phenocrysts and the groundmass glass. The method has been useful in determining the partition coefficient for trace elements of the rock. The present anion and cation partitioning strongly supports the “crystal structure control” mechanism (Onuma et al., 1968; Yurimoto and Sueno, 1984a). Each of the crystallographic site gives rise to a parabola-shaped peak on partition coefficient vs. ionic radius diagram. On the diagrams for three kinds of pyroxene, sharpness of their peaks is consistent with geometrical flexibility of the corresponding coordination polyhedra, and relative height between the partition curves for homovalent ions is controlled by electrostatic charge balancing their crystallographic sites.View full abstractDownload PDF (5456K) -
Iwao Kawabe1987 Volume 21 Issue 3 Pages 105-117
Published: 1987
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSA statistical method, named the Geochemical Filtering Method (GCFM) of earthquakes, has been proposed to identify seismogeochemical anomalies in the record of subsurface gas CH4/Ar ratios at two deep borehole wells in Matsuyama, Japan. This is based on the statistical reasoning that the absence of seismogeochemical anomaly can confidently be shown only by the observational data. The earthquakes occurring in a period when geochemical monitoring does not indicate any significant anomalous changes, are very important to infer what kind of earthquakes does not accompany any seismogeochemical anomalies. This provides us a non-subjective criterion by which the earthquakes unlikely to accompany geochemical anomalies can be selected. The criterion expressed in terms of magnitude and epicentral distance for earthquakes makes it much easier to demonstrate the physical correlation between particular earthquakes and unusual changes in geochemical records. The criterion is thought to represent a threshold relation concerning the appearance of seismogeochemical anomalies. The threshold relation for CH4/Ar anomalies in Matsuyama is found to be similar to those for Rn and geoelectric resistivity anomalies reported in the literature. The GCFM is applicable to other seismogeochemical monitoring data at any stations, and very useful in evaluating the reliability of the geochemical monitoring data.View full abstractDownload PDF (3488K) -
Akimasa Masuda, Osamu Kawakami, Yoshiteru Dohmoto, Teruo Takenaka1987 Volume 21 Issue 3 Pages 119-124
Published: 1987
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSIn 1979, Masuda and Ikeuchi found out a type of lanthanide tetrad effect in seawaters and phosphorite. At the time of this finding, it was logically reasoned that there should be another type of lanthanide tetrad effect which stands in conjugate relationship with the type as found for seawaters. This paper reports our success in evincing the previous reasoning about the bilateral appearances of the lanthanide tetrad effect, i.e., empirically disclosing the conjugate aspects of the effect in question. Thus, there are two types of tetrad effects for lanthanides in nature, which will be called W and M types for convenience sake according to their apparent shapes. The W tetrad effect is observed in the natural waters and related materials. This suggests that an M tetrad effect can be observed in the solid products probably having remained after leaching by aqueous medium, in which the W tetrad effect can be operative. Besides, the M tetrad effect have been found in an experiment concerning the lanthanide partitioning between CaSO4 and H2O. For the geological rock specimen, a remarkable M tetrad effect is recognized for the leucogranite from South China. To a lesser extent, a similar effect is found in a siliceous ore from the kuroko area.View full abstractDownload PDF (1666K) -
Yoshiyuki Nozaki, Mitsuyoshi Sato, Kenji Shimooka1987 Volume 21 Issue 3 Pages 125-131
Published: 1987
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSTwo sediment cores longer than 20 meters, obtained from two abyssal plains of the North Atlantic during the ESOPE cruise were analyzed for U and Th isotopes. In the Madeira Abyssal Plain sediment (ESOPE core 10), excess 230Th data do not show a simple exponential decrease with depth, being reflected by complex depositional history of the sediments, and hence the Th isotope data can only weakly constrain the rate of sediment accumulation. Relatively low 230Th concentration in the top 5 meters may be caused by rapid accumulation of turbiditic materials. That a significant excess 230Th exists even at depths of ∼20m in the core suggests that the average sedimentation rate is rapid, perhaps ∼10 of centimeters per thousand years. This high rate of sediment accumulation has resulted largely from frequent turbidites, and not from pelagic clay sedimentation. In the Nares Abyssal Plain sediment (ESOPE core 48), excess 230Th relative to 234U has been found down to ∼5m, showing its almost exponential decrease with depth. Based on the excess 230Th distribution, an average sedimention rate for the core is estimated to be 1.2 ± 0.3 cm/103 y.View full abstractDownload PDF (1739K) -
Hidetake Kakihana, Tomoko Ossaka, Takao Oi, Masaaki Musashi, Makoto Ok ...1987 Volume 21 Issue 3 Pages 133-137
Published: 1987
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSBoron isotopic ratios 11B/10B of five hot spring waters from the Kusatsu-shirane area, Japan have been measured mass spectrometrically. Their 11B/10B values are the same within experimental errors and the average value is 4.087. This suggests that the Kusatsu-shirane area belongs to the group of regions that show higher 11B/10B ratios. The secular change in the 11B/10B ratio has also been examined for one of the hot springs (Kusatsu-yubatake) and it is found that the ratio has been invariant (average of five measurements = 4.086) for the past twenty years.View full abstractDownload PDF (1255K)
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