The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
Online ISSN : 1883-0765
Print ISSN : 0021-4825
ISSN-L : 0021-4825
Volume 44, Issue 3
Displaying 1-6 of 6 articles from this issue
  • Keiichi Omori, Shuzo Hasegawa, Matsumi Nakayama
    1960 Volume 44 Issue 3 Pages 121-128
    Published: June 01, 1960
    Released on J-STAGE: August 07, 2008
    JOURNAL FREE ACCESS
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  • Basaltic rocks from the Abu district
    Yoshio Oji
    1960 Volume 44 Issue 3 Pages 129-141
    Published: June 01, 1960
    Released on J-STAGE: August 07, 2008
    JOURNAL FREE ACCESS
    The Cenozoic volcanic rocks distributed in the Abu district, Yamaguchi Prefecture are divided into the following three groups from geologic relations and petrographic characters: 1) andesites and rhyolites of the calc-alkali rock series in Miocene age, 2) basalts of the tholeiitic series in Pliocene, 3) trachybasalts and trachyandesites of the alkali rock series, and andesites (so called quartz basalt) of the calc-alkali rock series in Quaternary. In this district, Quaternary trachybasalts, trachyandesites, and andesites are widely distributed contrasting to the other two groups. Of these, one of the second group and sixteen of the third are chemically analysed. Abundant quartz xenocrysts and granitic xenolithes are contained in some trachybasalts and trachyandesites, and in all andesites. On the other hand, it is notable that olivine nodules are included in some andesites. These facts are suggestive to consider that andesites are also to have derived from the alkali rock series by the contamination of granitic rocks as already pointed out by several petrologists.
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  • Yoshio Katsui, Toshimasa Takahashi
    1960 Volume 44 Issue 3 Pages 142-151
    Published: June 01, 1960
    Released on J-STAGE: August 07, 2008
    JOURNAL FREE ACCESS
    The Daisetsu-Tokachi volcanic chain lying on the central highland of Hokkaido extends in NE-SW direction about 80km. It belongs to the inner subzone of the Kurile volcanic zone. This volcanic chain comprises vast pyroclastic plateaux of Pleistocene (or later Pliocene-Pleistocene) welded tuffs and Holocene stratocones, lava-domes and cindercones. The rocks of the volcanic chain vary in composition from basalt to rhyolite (46.79-71.57% in silica content), most of which are comprised in calc-alkali rock series (or hypersthenic rock series) and are characterized by common bearing of hornblende and biotite. The general chemical character of the rocks is the richness in alkalies (alkali-lime index=62) and in K2O/Na2O and Fe2O3/FeO ratios and poorness in FeO+Fe2O3/MgO ratio, which shows quite different from that of the pyroxene andesitedacite suite (calc-alkali rock series) of the Shiretoko-Akan volcanic chain belonging to the outer subzone of the same volcanic zone. The marked difference between the two rock suites of the outer and inner subzones owes its origin to the difference in character of their parental basaltic magmas; i.e. alkali-por tholeiite magma in the Shiretoko-Akan volcanic chain, and weak alkalic tholeite magma in the Daisetsu-Tokachi volcanic chain and alkali olivine basalt magma in the Japan Sea coast, respectively. Most hornblende (and biotite)-bearing rocks are considered to be derived through sialic contamination of the latter two magmas.
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  • Eikichi Narita
    1960 Volume 44 Issue 3 Pages 152-161
    Published: June 01, 1960
    Released on J-STAGE: August 07, 2008
    JOURNAL FREE ACCESS
    Along the Ishinomaki-Chyokaisan tectonic zone which crosses the north-eastern part of the Honshu are with NW-SE trend, some Miocene holocrystalline rocks surrounding the basement granite of pre-Tertiary are seen. In the Nuruyu district, northern part of Miyagi Prefecture, such holocrystalline rocks are found among Miocene propylitic rocks, and the main part of them presents dioritic character, but in part, doleritic or aplitic. In this paper, some interesting relations between those holocrystalline rocks and host propylitic rocks are described.
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  • Kazuo Yamaoka
    1960 Volume 44 Issue 3 Pages 162-170
    Published: June 01, 1960
    Released on J-STAGE: August 07, 2008
    JOURNAL FREE ACCESS
  • The measurements of thermo-electric potential of pyrite from Chichibu mine
    Teruo Suzuki
    1960 Volume 44 Issue 3 Pages 171-177
    Published: June 01, 1960
    Released on J-STAGE: August 07, 2008
    JOURNAL FREE ACCESS
    The measurements of thermo-electric potential are attempted on the section of pyrite from Chichibu mine. The tendencies of potential on the electrolytic-etching section are agree with one on the polished section, and reflect the heterogeneity of crystal which is recognized with the naked eye as parallel growth zoning obtained by electrolyticetching method. Consequently, these zones are consist of 12 zones that are p-type except two n-type zones.
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