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 40, Issue 4
Displaying 1-5 of 5 articles from this issue
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  • The preliminary report on the Yabakei welded tuff in Oita Prefecture
    Kiyohiko Ishii, Katsutoshi Tanida, Ken-ichiro Aoki
    1956 Volume 40 Issue 4 Pages 131-136
    Published: August 01, 1956
    Released on J-STAGE: March 18, 2008
    DOIhttps://doi.org/10.2465/ganko1941.40.131
    JOURNAL FREE ACCESS
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  • On the “Pb-bearing barite” from the Kawarage Mine in Akita Prefecture (1st report)
    Makoto Shiikawa, Ryoji Yamaguchi
    1956 Volume 40 Issue 4 Pages 137-148
    Published: August 01, 1956
    Released on J-STAGE: March 18, 2008
    DOIhttps://doi.org/10.2465/ganko1941.40.137
    JOURNAL FREE ACCESS
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    In this summer, we have found a weak radioactive mineral in a stream at the neighbourhood of the Kawarage Mine. It looks, apparently, to be a kind of barite, but differs from the latter as it is coated with a glossy or aggregate blackish-brown crystals and consists of three parts.
    We reserched it from the following view points: geological and mineralogical (Shiikawa), chemical and radioactive (Yamaguchi). Then, we concluded that either three parts were consisted mainly of “barium sulfate” contaminated with small percentages of Pb, Ca, Sr, Si and other elements and were a series of the sulfate sinter from the same origin, which may be the stream.
    In mineralogically, we found that at least the upper and middle parts were constructed with the fine stripe-structures. And this mineral had the different values of the interfacial angles from the ones of the normal barites and Hokutolites.
    The ratio PbSO4/BaSO4 of the total mineral and the upper part was 4.28/95.72 and 3.22/96.78 respectively.
    From these results, it may be called “Pb-bearing barite”
    Many questions are remained concerning to it. We are reserching it especially on the genetic information.
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  • Syenitic Rocks of the Utsugiono District, Yamaguchi Prefecture (I)
    Nobuhide Murakami
    1956 Volume 40 Issue 4 Pages 149-154
    Published: August 01, 1956
    Released on J-STAGE: March 18, 2008
    DOIhttps://doi.org/10.2465/ganko1941.40.149
    JOURNAL FREE ACCESS
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    Syenitic and alkali-granitic rocks are dike-like masses in the granitic rocks of the Utsugiono district. They are divided into the following six types.
    1. Leucocratic and garnet-syenitic rocks.
    2. Pyroxene-hornblende- and hornblende-syenitic rocks.
    3. Epidote-syenitic rocks.
    4. Potash-syenitic rocks.
    5. Porphyritic svenitic rocks.
    6. Syenitic aplite.
    Gradational relation can be found between syenitic rocks, which are very crushed and recrystallized, marginal alkali-granitic rocks, and outer granites. When alkali-granitic rocks contact with pegmatitic veins, there can not be found anv mutual intrusive relation, but plagioclase crystals in pegmatite are albitized and in latter rocks quartz often decreases.
    From these facts, it is concluded that shear zones in granitic rocks have been transformed to be syenitic by the effect of metasomatic reaction with alkali-solution and metamorphic differentiation in granitic rocks. The original solution might have been albitic and followed to the arrow direction in geological map, being gradually potassic by the reaction with granitic rocks, as shown by the relation between rock types, modal compositions, minerals, and the distribution of syenitic rocks.
    The peculiar syenitic rocks in the Setouchi region might equally be interpreted as of similar metasomatic origin.
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  • Calcic plagioclases associated with chloritoid schists in the Hitachi District, Ibaragi Prefecture
    Yotaro Seki
    1956 Volume 40 Issue 4 Pages 155-162
    Published: August 01, 1956
    Released on J-STAGE: March 18, 2008
    DOIhttps://doi.org/10.2465/ganko1941.40.155
    JOURNAL FREE ACCESS
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    The modes of occurrence, optical properties and X-ray powder pattern of calcic plagioclases with chemical composition of about An98-Ab2 found in the chloritoid schists in the Hitachi district are described and some of geological considerations are discussed.
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  • Notes on inclusions associated with migmatites at Saruru River district in Hidaka, Hokkaido
    Yono Sotozaki
    1956 Volume 40 Issue 4 Pages 163-168
    Published: August 01, 1956
    Released on J-STAGE: March 18, 2008
    DOIhttps://doi.org/10.2465/ganko1941.40.163
    JOURNAL FREE ACCESS
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    The so-called migmatites at the Saruru River district in the southeastern Hidaka Mountains are divided into two main types according to their petrographic characters, namely, the granitic migmatite and cordierite migmatite. The writer has described, in the present paper, the modes of occurrence and microscopical features of various inclusions in these two migmatites.
    The inclusions in the granitic migmatite and cordierite migmatite, which may be classified into the following groups, viz., the argillo-siliceous, calcareous and amphibolitic rocks. The gabbroic inclusion is commonly xenolith-like, which is found only in the granitic migmatite. As shown in the geological map the gabbroic inclusion occurs along the special zone.
    The argillo-siliceous and calcareous inclusions are probably explained as relics of the original country rocks which have escaped granitization. The gabbroic inclusion may be interpreted as a relict dike of the original country rocks which have escaped granitization.
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