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 81, Issue 4
Displaying 1-3 of 3 articles from this issue
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  • REE abundances of the effusive and intrusive rocks from the Shimokawa mining area, Hokkaido, Japan
    SATOSHI KOSHIMIZU, OSAO SAWAI, TAKEO BAMBA
    1986 Volume 81 Issue 4 Pages 129-137
    Published: April 05, 1986
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.81.129
    JOURNAL FREE ACCESS
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    The Shimokawa mining area is an example of collision orogenesis formed by accretion of Shimokawa diabase complex and Nisama igneous complex. The former, which consists of pillow lava, diabase sheet and diabase dike, is believed to be formed with turbidite strata in a fore-arc basin of Cretaceous age. Whereas, the latter is a gabbroic intrusion mainly consisting of olivine gabbro, norite and diorite.
    Major chemical element compositions and REE abundances of main rock types of above two complexes are discussed. It is inferred that Shimokawa diabases are of tholeiitic rock series. The differentiation index (D. I.) shows that pillow lava can not be distinguished from the diabase sheet whereas diabase dike has significantly high value. REE abundances of above three rock types decrease with the increase of D. I. value, especially towards lighter element.
    Three rock types of the Nisama igneous complex are wholly of calc-alkaline rock series. Both REE abundances and D. I. values increase in the order norite-olivine gabbro-diorite.
    Chondrite-normalized REE patterns and (La)EF/(Sm)EF in terms of ∑ FeO/MgO led to the conclusion that the Shimokawa diabases belong to solid type and the Nisama igneous rocks to liquid type, respectively. The Shimokawa diabase complex, which has been believed to belong to MORB by many investigators, might be formed in an island arc environment.
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  • Oyelite from Suisho-dani, Ise, Mie Prefecture
    Tetsuo Minakawa, Sachio Inaba, Shigetoshi Noto
    1986 Volume 81 Issue 4 Pages 138-142
    Published: April 05, 1986
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.81.138
    JOURNAL FREE ACCESS
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    Oyelite was found from serpentinite body in Suisho-dani, Ise City, Mie Prefecture, Japan. Oyelite, which occurs as white massive aggregates in rodingitic rock derived from gabbroic pegmatite, is accompanied with hydrogrossular, 11Å-tobermorite, bultfonteinite, ettringite group mineral, apophyllite and calcite.
    The cell dimensions are a=11.23(1)Å, b=7.24(1)Å, c=20.42(1)Å, and V=1, 660(2)Å3. The empirical formula (based on O=29) by wet chemical analysis is Ca10.01, B1.74 Alp0.19 Sie8.05 O29 12.25 H2O, corresponding to the ideal formula Ca10 B2 Si5 O29 12 H2O. The endothermic peak in DTA appears at 200°C, and the exothermic peak appers at 8011°C. The major weight loss by TG is observed in the regions at about 200°C. Oyelite, which heated at 300°C and 1, 0001°C for 1 hr, changes into 9.3Å-tobermorite and wollastonite in the X-ray diffraction patterns. The infrared absorption spectrum at 25°C gives strong peaks at 3, 500-3, 000, 1, 440, 965, 857, and 463cm-1, and after heating at 300°C, the I. R. spectrum indicates absorption peaks at 3, 600-3, 400, 1, 390, 970, and 475cm-1.
    Oyelite was produced from a hydrothermal solution with BF3, in the later stage of the rodingitization (calcium metasomatism).
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  • [title in Japanese]
    1986 Volume 81 Issue 4 Pages 143-159
    Published: 1986
    Released on J-STAGE: July 13, 2012
    DOIhttps://doi.org/10.2465/ganko1941.81.143
    JOURNAL FREE ACCESS
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