The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
Online ISSN : 1883-0765
Print ISSN : 0021-4825
ISSN-L : 0021-4825
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Volume 64, Issue 4
Displaying 1-3 of 3 articles from this issue
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  • PETROLOGY OF MAGNETITE-BEARING ULTRAMAFIC AND MAFIC INCLUSIONS FROM IKI ISLAND, JAPAN
    KEN-ICHIRO AOKI
    1970 Volume 64 Issue 4 Pages 107-122
    Published: October 05, 1970
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.64.107
    JOURNAL FREE ACCESS
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    Magnetite-bearing olivinc gabbro, gabbro, anorthosite and hypersthene gabbro inclusions, which are the most common series of cognate ultramafic and mafic inclusions in Iki Island, Japan, occur in several alkali basalt flows. New analyses are presentatcd for one host basalt, ten inclusions, one plagioclasc, five clinopyroxenes and one orthopyroxene.
    It is reasonable to conclude from petrographic and chemical evidence that magnetite-bearing olivine gabbro, gabbro and anorthosite inclusions would be produced from hypersthenc-normative alkali basalt magma which has been moderately differentiated and reached the middle stage of differentiation under high oxygene partial pressures at a depth of less than 15km, while hypersthene gabbro inclusion would be formed from calc-alkaline basalt magma derived from alkali basalt magma with contamination of sialic rocks.
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  • Plagioclases in some granitic rocks, Kitakami mountainland, Northern Japan
    Part I. Relationship between scatter in the optic axial angles and ordering degree.
    Satoshi Kanisawa
    1970 Volume 64 Issue 4 Pages 123-129
    Published: October 05, 1970
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.64.123
    JOURNAL FREE ACCESS
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    Optical characteristics of plagioclases in the Tono, Hitokabe, Uchino, Hirota, Ichinohe, Aoganebashi and Ochiai granitic masses in the Kitakami mountainland are investigated. Plagioclases in the Tono and the Hitokabe masses which are thought to be comparatively deep intrusives show the typical low-temperature type i. e. high ordering degree (0.8-1.2) proposed by Uruno (1963), and those in the Ichinohe mass show the intermediate ordering degree (0.6-1.0). However plagioclases in the Uchino, Hirota, Aoganebashi and Ochiai masses which are thought to be shallow and small intrusives show wide range of ordering degree. Optic axial angles of plagioclases having limited ordering degree show good agreement with the 2Vz-An content curve but those having wide range ordering degree do not show distinct relation between 2Vz and An content, namely the deviation of optic axial angles from the ideal curve is also due to cooling rate of granitic magma.
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  • Apophyllite in the druse cavities of biotite andesite from Makinokawa, Ehime Prefecture
    Kiyoshi Ishibashi
    1970 Volume 64 Issue 4 Pages 130-136
    Published: October 05, 1970
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.64.130
    JOURNAL FREE ACCESS
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    Several excellent crystals of apophyllite, calcite, zeolite and datolite are found in the druse cavities of biotite andesite from Makinokawa quarry, Ehime Prefecture.
    The apophyllite has well defined outline with c(001), p(111) and a(100) crystal faces. The optical properties, X-ray powder data and chemical composition are good accordance with those of fomer results.
    The genetic relation of apophyllite and other druse minerals is discussed briefly on the concentration of volatile elements into hydrothermal solution of post magmatic stage.
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