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Volume 25 (1985)
- Issue 4 Pages 139-
- Issue 3 Pages 101-
- Issue 2 Pages 53-
- Issue 1 Pages 1-
Volume 25, Issue 3
Displaying 1-5 of 5 articles from this issue
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Tsutomu NISHIYAMA1985 Volume 25 Issue 3 Pages 101-106
Published: September 10, 1985
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSMinerals comprising rocks are attacked by meteoric water and air and alter their structual and chemical properties. The minerals change to intermediate and/or new minerals in such weathering process. In this paper, relatively early products of the chemical weathering from mica minerals, chlorite and smectite are referred.
The vermiculite weathered from biotite in schalstein at Ofuku, Yamaguchi Pref. has cube-like materials in about 50Å size at the edge of the crack on surface and in an exforiated interlayer space. Chlorite-vermiculite interstratified minerals weathered from chlorite in schalstein and sedimentary rocks from Tobigamori, Iwate Pref. are estimated comprising about 50% of a vermiculite-like layer by X-ray diffraction analysis. The degree of swelling of their interlayers after various K+-treatments distinctively change among samples and with particle sizes of the samples. The interstratified chlorite-vermiculite alters to kaolinite with the relationship of syntaxy.View full abstractDownload PDF (5269K) -
Takahisa YOSHIMURA1985 Volume 25 Issue 3 Pages 107-112
Published: September 10, 1985
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSIllite/smectite mixed-layer minerals occur widely in diagenetic process of argillalaceous and acid pyroclastic sediments. The relative proportion of constituent layers and ordering in the mixed-layer structure are regarded as reflecting formation temperature (Fig. 1). Chemical changes from random to regular interstratification are remarkable in tetrahedral Al and octahedral Al/(Al+Mg+Fe) ratio (Fig. 2).
Chlorite/saponite mixed-layer minerals are found in MgFe bearing sediments such as basic-intermediate pyroclastics. The proportion of chlorite layers in the interstratification is discontinuous and is concentrated on ranges of less than 10, 50, 75 and morethan 90%. Randomly interlayering of chlorite/saponite occurs as replacement products of volcanic glass. An increase in chlorite layers with increasing burial depth is observed in the Miocene pyroclastic rocks of Yamagata-Yoshino (Fig. 3). Whereas corrensite type minerals occurring as cementing materials of andesitic sandstone are found over the thick strata regardless of burial depth. Chemical changes of chlorite/saponite mixed-layer with increasing burial depth are characterized by an increase of tetrahedral Al and octahedral Fe (Fig. 4).View full abstractDownload PDF (579K) -
Haruo SHIROZU1985 Volume 25 Issue 3 Pages 113-118
Published: September 10, 1985
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSFormation of clay minerals by hydrothermal action and their mineralogical properties have been reviewed with some discussions on the relations of hydrothermal alteration to weathering and diagenes, on the chemical compositions of dioctahedral 2:1 clay minerals and chlorite minerals, and on the polytypes of some sericite minerals. There are wide variations in the parent materials, the water resources, the alteration conditions and processes of the hydrothermal alterations, and almost all kinds of clay minerals with moderate crystallinity are found in the alteration envelopes in Japan. Hydrotherrnal dioctahedral Inica minerals known as sericite are characterized by their mineralogical properties intermediate between muscovite and illite. It is noticed that the typical fine-grained clay minerals in the dioctahedral 2:1 type and chlorite minerals (sericite, illite, glauconite, niontmorillonite, leptochlorite, sudoite, and donbassite) show nonintegral hut approximately fixed populations of interlayer cations.View full abstractDownload PDF (693K) -
Minoru UTADA1985 Volume 25 Issue 3 Pages 119-125
Published: September 10, 1985
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSAuthigenic minerals, including clay minerals, have been formed at subsurface of the earth under very wide conditions. Practically the “zone” which is defined by assemblage of them is convenient for recognizing a restricted physicochemical condition. The comhnation, sequence, morphology, relation to stratigraphy and geologic structure of these zones indicate more details of varying conditions. The author cites an instance of various kinds of zoning which are constituted by the zones of zeolite-lay-ilica minerals, correlating to different alteration facies.View full abstractDownload PDF (799K) -
Hiroshi Kamata1985 Volume 25 Issue 3 Pages 126-133
Published: September 10, 1985
Released on J-STAGE: September 20, 2011
JOURNAL FREE ACCESSDownload PDF (854K)
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