All issues
Volume 22 (1988)
- Issue 6 Pages 237-
- Issue 5 Pages 183-
- Issue 4 Pages 143-
- Issue 3 Pages 89-
- Issue 2 Pages 47-
- Issue 1 Pages 1-
Volume 22, Issue 6
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
-
Takeru Yanagi, Hiroshi Arikawa, Reiko Hamamoto, Isamu Hirano1988 Volume 22 Issue 6 Pages 237-248
Published: 1988
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSIn order to define the contaminant and the contamination process, strontium isotopic compositions were determined on thirty-six rock samples from lava flows of the Quaternary Kinpo volcano in the Beppu-Shimabara Graben, Southwest Japan. Forty-two rock samples were also analyzed for major chemical compositions. The rocks are all subalkalic. All but a few tholeiitic basalts are calc-alkalic with abundant phenocrysts. The rocks are characterized by rather high Sr contents, ranging from 387 ppm to 1106 ppm. 87Sr/86Sr ratio ranges from 0.70377 to 0.70537. Marked linear relationships are found between 87Sr/86Sr and 1/Sr of the rocks. Repetitive occurence of basalts and basaltic andesites in the stratigraphic succession and lines of petrographic evidence for magma mixing suggest the operation of a periodically refilled magma chamber under the Kinpo volcano. The linear relationships between 87Sr/86Sr and 1/Sr, and also between some major oxide components are interpreted as the manifestation of eruption of lavas during the repeated magma mixing. The increase of 87Sr/86Sr ratio is postulated to be due to the contamination by melts derived from the granulitic basic lower crust during the upward migration of the chamber to attain the heat balance.View full abstractDownload PDF (3345K) -
Yoshiko Fujiwara, Shinji Ohsawa, Kunihiko Watanuki, Bokuichiro Takano1988 Volume 22 Issue 6 Pages 249-256
Published: 1988
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSA nitrate ion-selective electrode, Orion model 93-07, has been examined to determine in situ tri- to hexathionate in an active crater lake. The electrode (ISE) showed a linear response to aqueous polythionates within a range of 10-5-10-2M. The slope in the plot of log concentration vs electrode potential was slightly larger than the Nernst slope for S3O62-, S4O62- and S5O2-6, while a considerably larger one was observed for S6O2-6. Selectivity coefficients determined by the fixed interference method were k34pot=23, k45pot=10 and k56pot=7.0 for a pair of S3O2-6--S4O2-6, S4O2-6-S5O2-6 and S5O2-6-S6O2-6, respectively. The observed variation in the electrode potential for polythionate solution was best explained in terms of the Nicholsky-Eisenman equation. Chloride and sulfite ions less than 2500 ppm and 500 ppm, respectively, did not interfere with the potential measurement. The sum of three polythionates (tetra-plus penta- plus hexathionate) of volcanic origin determined by the ISE method has agreed well with those by the microbore column HPLC.View full abstractDownload PDF (1962K) -
Shun-ichiro Igari, Susumu Sakata1988 Volume 22 Issue 6 Pages 257-263
Published: 1988
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSCarbon isotopic ratios (13C/12C) and chemical compositions of methane (C1), ethane (C2), propane (C3), i-butane (i-C4) and n-butane (n-C4) were measured for natural gases from the Japanese major oil and gas fields. The C1/(C2+C3) vs. δ13C(C1) plot suggests that most samples analyzed in the present study are of thermogenic origin with a minor contribution of biogenic gases. Some gases show unusually high ratios of C2/C3 and i-C4/n-C4, and low ratios of C3/i-C4 (Unusual-Hydrocarbon-Ratio gases: UHR gases). The carbon isotopic ratios and hydrocarbon compositions strongly suggest that these unusual ratios were caused by the chromatographic effect of sediments during migration of the gases. By comparing hydrocarbon ratios (C1/C2, C2/C3, C2/i-C4, C2/n-C4, C3/i-C4, C3/n-C4 and i-C4/n-C4) of the UHR and normal gases, it was found that the natural gases tend to lose their hydrocarbons during migration in the order: n-C4 ≅ C3 > C2 = i-C4 > C1.View full abstractDownload PDF (1699K) -
Carlo Gorgoni, Olinto Bonori, Salvatore Lombardi, Gianni Martinelli, G ...1988 Volume 22 Issue 6 Pages 265-273
Published: 1988
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSRn-222 and total helium contained in saline waters and associated gaseous fluids from a series of mud volcanoes occurring along the northeastern border of the Apennine chain (northern Italy) have been determined as possible precursors of local earthquakes. Investigations spanned over about one year (May 1986-May 1987) during which a series of low- to medium-magnitude (M = 3-4.5) local earthquakes occurred with distinct focus. Spike-like Rn anomalies were almost systematically observed a short time (hours to few days) before and after the main shocks. These anomalies were frequently accompanied by slight but significant short-term changes in water chemistry. A unique very strong He anomaly was recorded in coincidence with a shock in an area very close to the focus. The significance of the observed short-term anomalies of Rn and hydrochemical parameters (chlorinity, alkaline earths content) is explained in terms of an upsetting of the equilibrium between two chemically distinct (pellicular and normal) connate waters in confined reservoirs. Pellicular water trapping radiogenic Rn would be abruptly liberated into normal connate water by a tectonic stress change. In most cases, helium seems to be insensitive to seismic events, this probably being due to the shallowness of the foci. The data confirm that mud volcanoes represent very sensitive natural systems for predicting local earthquakes.View full abstractDownload PDF (2723K) -
Tamotsu Oomori, Atsuko Kyan, Yasushi Kitano1988 Volume 22 Issue 6 Pages 275-283
Published: 1988
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSMagnesian calcites were precipitated from 10 mM Ca(HCO3)2 (Ca2+, 400 mg/l) solutions containing 35 or 53.5 mM Mg ions (Mg2+, 850 or 1300 mg/l) in the presence of fluoride and phosphate ions in various concentrations. Magnesian calcite formation from aqueous solution was favored by the presence of fluoride ions (0.5 to 2.5 mM) or phosphate ions (0.025 to 0.5 mM) in a parent solution. Aragonite and/or monohydrocalcite are formed below or above the critical concentrations of these ions. The presence of phosphate or fluoride ions in a solution inhibits adsorption of Mg2+ ions on calcite surface, which may cause the magnesian calcite formation.View full abstractDownload PDF (2529K) -
Yutaka Kanai1988 Volume 22 Issue 6 Pages 285-292
Published: 1988
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSThe geochemical behavior of uranium, radium and radon in the Masutomi spring district, Yamanashi Prefecture, central Japan, was studied. The uranium concentrations in the spring waters range from 0.01 to 2.07 ppb (average 0.27 ppb). The 234U/238U activity ratios in the spring waters range from 0.98 to 2.42, and show an inverse correlation with the 238U concentrations. The measurement of redox potentials of the waters shows that the waters are reductive. This may be the reason for the low uranium concentrations. Alpha recoil dissolution of 234Th explains the behavior of 234U. Radioactive disequilibria are also observed in 226Ra/238U, 222Rn/238U, and 222Rn/226Ra ratios. Highly exess radon is attributed to both the source granite rocks and the radium rich precipitates near the surface. On the other hand, the behavior of radium as well as other general ions such as sodium is explained by mixing or dilution of a deep water with surface waters.View full abstractDownload PDF (2418K) -
Yuji Sano, Hiroshi Wakita1988 Volume 22 Issue 6 Pages 293-303
Published: 1988
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSWe have collected 21 gas samples of various kinds such as volcanic gas, hot spring gas and CH4-rich natural gas in the Hokkaido Island. Helium and neon in the samples were purified in a vacuum line and the 3He/4He and 4He/20Ne ratios were measured by a mass spectrometer. Observed 3He/4He and 4He/20Ne ratios vary significantly from 0.242 × 10-6 to 9.58 × 10-6 and from 0.53 to 96, respectively. There is no correlation between the 3He/4He and 4He/20Ne ratios. Taking into account present data as well as published ones, geographical distribution of 3He/4He ratios indicates a clear contrast, high in the volcanic arc and low in the forearc region. The distribution pattern agrees well with the data of Northeast Japan (Sano and Wakita, 1985) and those of the North Island of New Zealand (Sano et al., 1987). Higher 3He/4He ratios than air in the volcanic arc region can be well explained by the presence of an uprising magma. Lower 3He/4He ratio in the forearc region is attributed to the radiogenic helium accumulated in crustal rocks. A positive correlation is found between the common logarithms of 3He/4He ratio and heat discharge rate of hot springs in the area. The tendency can be explained by a combination of magma aging and the dilution of magmatic fluids by local groundwater.View full abstractDownload PDF (3427K)
- |<
- <
- 1
- >
- >|