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Volume 8 (1974)
- Issue 4 Pages 157-
- Issue 3 Pages 109-
- Issue 2 Pages 47-
- Issue 1 Pages 1-
Volume 8, Issue 1
Displaying 1-7 of 7 articles from this issue
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Yoshiro Tsuzuki, Shinjiro Mizutani, Hiroshi Shimizu, Hiroshi Hayashi1974 Volume 8 Issue 1 Pages 1-20
Published: 1974
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSK-feldspar was treated with acid solutions containing various concentrations of H+ and K+ at 210°∼270°C in silica glass tubes. Amounts of Si, Al and K in the solutions were determined after each experimental run. The alteration products comprised kaolinite in general, although sometimes a 12Å mineral appeared and only amorphous material was observed in strong acid solutions. The rate of reaction depends on the chemical composition of solution and the temperature. On the basis of the experimental results, the alteration process can be expressed by the following rate formula, α = 1 - exp(-ktn) where α is the fractional amount of kaolinite in all the minerals present, t is time, and k and n are constants. On the assumption that Al is an inert component, that SiO2 behaves as a mobile component capable of being dissolved, migrating in solution and being precipitated out of it, and that K is mobile and flows out of the system, the zonal arrangement of inner kaolinite zone and outer silicified zone, which can be observed in some kaolin deposits, is illustrated numerically in a model involving a kinetic process.View full abstractDownload PDF (9280K) -
Hiroshi Kamiya, Atsuko Ozaki, Masayuki Imahashi1974 Volume 8 Issue 1 Pages 21-26
Published: 1974
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSThe study reported in this paper concerns the role of salts in dissolution of powdered quartz. Kinetic dissolution experiment was carried out in acid media at 60 and 90°C to know the mechanism of acid alteration of rocks. The dissolution rate of silicon was accelerated by addition of such salts as sodium chloride and sodium sulfate in solution above about pH 2 but not affected below about pH 2. An accelerating effect of divalent sulfate ions was greater than that of monovalent chloride ions. Moreover, this effect became remarkably greater with increasing concentration of salts, increasing temperature and increasing pH value from 2 to 4.View full abstractDownload PDF (2444K) -
Masahiro Yamamoto1974 Volume 8 Issue 1 Pages 27-35
Published: 1974
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSSulfur isotope study of the Iwami Kuroko deposits shows that sulfide minerals from the disseminated ores, the bedded ores, the mudstones and the gypsum ores have δ34S values ranging from +1.2 to +5.5‰, from -0.8 to +5.4‰, from -7.7 to -1.29‰, and from -15.3 to +5.4‰, respectively. Pyrites from the bedded ores exhibit a wider spread in the δ34S value (-0.8 to +5.4‰) than pyrites from the disseminated ores (+3.1 to +5.5‰), and chalcopyrites of the bedded ores have δ34S values ranging from +0.9 to +2.2‰, which are lower than those for chalcopyrites of the disseminated ores (+2.1 to +4.6‰). δ34S values for barites from the bedded ores and the mudstones and gypsums from the gypsum ores are fairly uniform, ranging from +19.5 to +23.2 ‰. Sulfur isotope temperatures calculated for sphalerite-galena pairs of the disseminated ores are fairly constant, giving the values of around 290°C, which are not so much different from 250°C obtained for most sulfide pairs from the Kuroko deposits in Northeast Japan (KAJIWARA and DATE, 1972). Other sulfide pairs including pyrite and/or chalcopyrite, however, give so much variable isotope temperatures. The observed isotopic distribution in the disseminated ores and the bedded ores may be explained by the assumption that pyrite and chalcopyrite were preferentially contaminated by biogenic sulfur during and/or after the ore deposition. Low and variable δ34S values obtained for pyrites from the mudstones and the clay of the gypsum ores suggest that these pyrites are of biogenic origin.View full abstractDownload PDF (4547K) -
Naotatsu Shikazono1974 Volume 8 Issue 1 Pages 37-46
Published: 1974
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSPhysico-chemical properties of ore-forming solution responsible for the formation of Toyoha Pb-Zn vein type deposits, Japan are estimated on the basis of the studies on mineral assemblage and fluid inclusions. The concentration of total dissolved sulfur is estimated in a range from 10-2 to 10-3 mol/l which is consistent with that of hot springs accompanying sulfide deposition. The probable ranges of the other variables such as pH, NaCl and base metal contents of ore-forming solution are also calculated. These estimated values are compared with those of hot springs, Broadland geothermal area, New Zealand, now depositing sulfide minerals. It is concluded that both hydrothermal solutions are very similar with respect to physico-chemical properties and both are characterized by (1) total dissolved sulfur in excess over base metals, (2) neutral to slightly alkaline pH, and (3) low NaCl content. These characteristic features are very different from those of Salton Sea geothermal brine which is now depositing sulfide minerals with total dissolved sulfur insufficient for base metals, slightly acid to neutral, and has high NaCl content.View full abstractDownload PDF (4955K) -
1974 Volume 8 Issue 1 Pages e1a
Published: 1974
Released on J-STAGE: February 06, 2009
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1974 Volume 8 Issue 1 Pages e1b
Published: 1974
Released on J-STAGE: February 06, 2009
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1974 Volume 8 Issue 1 Pages e1c
Published: 1974
Released on J-STAGE: February 06, 2009
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