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Volume 57 (1967)
- Issue 6 Pages 215-
- Issue 5 Pages 177-
- Issue 4 Pages 137-
- Issue 3 Pages 81-
- Issue 2 Pages 39-
- Issue 1 Pages 1-
Volume 57, Issue 4
Displaying 1-3 of 3 articles from this issue
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Koichi Tazaki1967 Volume 57 Issue 4 Pages 137-144
Published: April 05, 1967
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSSix clinopyroxenes of the ultrabasic rocks such as wehrlite, olivine clinopyroxenite, olivine bearing hornblende clinopyroxenite and clinopyroxene hornblendite have been chemically analyzed (Table 1).
They are slightly iron rich comparing with those from the peridotite of Dun Mountain and of Horoman.
The Ca: Mg: Fe ratios are from Ca44.9 Mg48.5 Fe6.6 to Ca44.2 Mg46.0 Fe9.8 and are plotted as shown in Fig. 1.
The clinopyroxenes in the Hayachine ultramafic complex in the Kitakami mountains reported by Onuki (1963) are plotted in the field near the one of the northern Kanto mountains.
Total Al contents on the basis of 6 oxygen atoms are from 0.126 to 0.244 and the proportions of Al of four fold coordinate are 6.25 to 8.30%. Ca-Tschermak' molecule calculated by the method proposed by Kushiro (1962) are variable. Total Al contents and the proportion of Al in Z position increase in accordance with enrichment of Fe''+Fe'''+Mn in the course of fractional crystallization as shown in Fig. 2. The proportions of Al in Z position vary in accordance with the amounts of total Al as shown in Fig. 3, however, it is clear that the ratio between amounts of AlIV and total amounts of Al decrease when the total Al contents in clinopyroxene increase.
It is therefore, suggested that the enrichment of Al in magma is the most effective factor controlling the amount of Al in clinopyroxene especially in the case of ultrabasic intrusives in the northern Kanto mountains.View full abstractDownload PDF (410K) -
with special reference to alunitizaiHiroshi Abe, Tsunehiko Takeuchi1967 Volume 57 Issue 4 Pages 145-159
Published: April 05, 1967
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSThe aluntiization of a series of rock types varying in silica content has been studies at low temperature and pressure. The natural volcanic rocks (rhyolite, olivine hypersthene augite andesite and hypersthene augite dolerite) and 5%solution of aluninum. sulfate are sealed into a precision autoclave and kept for 360 hours under the environmental conditions at 200°C. and the pressure 180kg/cm2. Under the microscope, the above-mentioned fresh rock was alterd with the order of groundmass→ phenocrystic minerals and the alteration front is extensively replaced by alunite. According to the result of the examinations by the D. T. A., the X-ray diffraction and the chemical analyses, it was ascertained that rhyolite was most sensitive to alunitization among other volcanic rocks. The reaciton between aluminum sulfate solution and feldspar which is constituent mineral for rhyolite is stressed. the theoretical standard free energy of the formation of alunite is approximately-19kcal/mole at 298°K, 1 atm.View full abstractDownload PDF (1905K) -
Nobuhide Murakami1967 Volume 57 Issue 4 Pages 160-175
Published: April 05, 1967
Released on J-STAGE: August 07, 2008
JOURNAL FREE ACCESSIn Southwest Japan, ugrandite garnests of various compositions are frequently found in the metasomatic syenitic rocks occurring in granites. Some of these garnests were separated, and studied chemically and optically. Their chemical compositions, and physical and optical properties are given in Table 2 and 3, respecitvely. The equilibrium relations between the garnests and some other coexisthing minerals such as hedenbergitic pyroxene, aegirine-augite, and plagioclase, are discussed in detail.View full abstractDownload PDF (1251K)
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