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Volume 16 (1976)
- Issue 3-4 Pages 81-
- Issue 2 Pages 56-
- Issue 1 Pages 1-
Volume 16, Issue 2
Displaying 1-3 of 3 articles from this issue
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especially from the viewpoint of the collape foreknowledge of the Shirasu cliffKatsutoshi TOMITA, Kazumi ONISHI1976 Volume 16 Issue 2 Pages 56-62
Published: June 25, 1976
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSClay minerals in the Shirasu (non-welded pumice flow deposits) which is widely distributed in Kagoshima Prefecture were studied. Clay minerals are included only in the surface part of the Shirasu cliffs, and they are classified into two groups by their clay mineral association; 1) a group mainly composed of 10Å halloysite, 2) a group including montmorillonite, illite, and irregular mixed layer mineral of kaolin/montmorillonite. Considerable amounts of clay minerals are included in the fallen parts of the Shirasu after collapse of the cliffs, wheras very few amounts or none of clay minerals are included in the remained parts of the Shirasu cliffs.
This fact suggests the possibility of foreseeing a certain failures of natural or cut slopes of the Shirasu by estimating the amount of clay minerals included in the surface parts of the Shirasu cliffs.View full abstractDownload PDF (663K) -
Tsuyoshi HAYASHI1976 Volume 16 Issue 2 Pages 63-76
Published: June 25, 1976
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSWeathering state of the diluvial sediments widely distributed in northwest Taiwan where the climate is subtropical hydrometeor was investigated mineralogically and chemically. Some observed varieties on the clay mineral composition and the chemical properties of weathered sediments were attributed to the differences of topographical location of sediments.
1) When the sediments are located in the well-drained slopes or the top of the diluvial plateau, the clay fraction of the weathered sediments which are colored in red shows the praperties of about 5 meq/100g-clay in CEC, high degree of base unsaturation, strong acidity (pH 4.5) and about 2.2 in SiO2/Al2O3 molar ratio. The clay is composed of illite, hydrous illite, kaolin, hydroxy-Al interlayered 14Å mineral and about 15% hydrous iron oxides in the upper part of the profile, while illite is dominant in the lower part.
2) Where the sediments are in the wet depressions, a large amount of black organic matter and montmorillonite are predominant at the top of the profile. Illite, kaolinite and montmorillonite are found in the lower part. Although the sediments are slightly acidic (pH 6), the hydrological conditions, under which silica, bases and colloidal substances are being supplied from the upstream or the upper part of the profile, seem to be favorable to develop these clay minerals. The molar ratio, SiO2/Al2O3, of the clay is abont 3.2.View full abstractDownload PDF (8056K) -
Takashi WATANABE, Yoshiharu NAKAJIMA1976 Volume 16 Issue 2 Pages 76-78
Published: June 25, 1976
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSLattice images of a polytype of sericite were observed by a high resolution electron microscope with a tilting apparatus. The sericite specimen used in this study was collected from the alteration zone of a Kuroko deposit. The polytype identified from the x-ray pattern was 2M1.
Two types of two dimensional lattice images are observed in the plane which contains the [001] and [110] directions. The one consists of a periodicity of about 20Å parallel to the [001] direction and that of about 5.3Å crossing it with an angle of about 86°, and the other has 20Å and 4.5Å periodicities crossing mutually with an angle of about 60°. These lattice images correspond to the projection of the 2M1 structure on the plane containing the [001] and [110] directions.View full abstractDownload PDF (2360K)
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