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 79, Issue 8
Displaying 1-4 of 4 articles from this issue
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  • Geological significance of the amphibolite from the Gokasho-Arashima Tectonic Line in the middle part of the Shima Peninsula
    Shin-ichi Yoshikura, Teiichi Terashima
    1984 Volume 79 Issue 8 Pages 311-317
    Published: August 05, 1984
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.79.311
    JOURNAL FREE ACCESS
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    The Gokasho-Arashima Tectonic Line in the Chichibu Belt of the Shima Peninsula is characterized by the distribution of the huge volume of serpentinite and has been considered as eastward extension of the Kurosegawa Tectonic Zone.
    Two small blocks of amphibolite were found in the serpentinite of this tectonic line. These amphibolites are composed mainly of hornblende and prehnite after plagioclase. Their petrographic characteristics are similar to the amphibolite of the Kurosegawa Tectonic Zone in Kyushu, which occurrs as tectonic block in serpentinite and is altered to rodingite at the marginal part by metasomatic reaction between the amphibolite and serpentinite.
    Some workers suggested that the Gokasho-Arashima Tectonic Line is one of the branch fault from the Median Tectonic Line that was formed as Riedel shear during left-lateral movement of the Median Tectonic Line. Left-lateral movement of the Gokasho-Arashima Tectonic Line remobilized the pre-existed serpentinite of the Kurosegawa Tectonic Zone along the GokashoArashima Tectonic Line. So, the Gokasho-Arashima Tectonic Line now oblique to the general trend of the Chichibu Belt in the Shima Peninsula is different from the Kurosegawa Tectonic Zone in Kyushu and Shikoku.
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  • Trace elements in the Tertiary igneous rocks from Cape of Ashizuri, Kôchi Prefecture, Southwest Japan
    Nobuhide Murakami, Yasuyuki Masuda
    1984 Volume 79 Issue 8 Pages 318-328
    Published: August 05, 1984
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.79.318
    JOURNAL FREE ACCESS
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    Thirteen trace elements, Co, Sc, Ba, Th, Rb, Cs, La, Ce, Sm, Eu, Tb, Yb and Lu in the Tertiary igneous rocks from Cape of Ashizuri, Southwest Japan, were analyzed by the instrumental neutron activation technique and in part by X-ray fluorescence method. The obtained data exhibit a relatively good correspondence to those in the A-type granites after Loiselle and Wones (1979) and those from NE Australia (Collins et al., 1982), excluding some small differences. This confirms the previous results obtained on the major element geochemistry and also on the petrographic characters. The chondrite-normalized REE patterns of the rocks investigated show a marked enrichment in the light and middle rare earth elements in comparison with those on the granitic rocks from Chugoku area, Southwest Japan (Masuda et al., 1974). One of the investigated specimen, syenite porphyry, has a high enhancement also in the heavy rare earth elements. This seems to be due to the late crystallizing amphibole and other minerals from the liquids enriched in volatiles as discussed by Bowden and Whitney (1974). Distinct negative Eu anomaly which tends to become small with increase of quartz, is recognized in the most of the investigated rocks with the exception of gabbro, alkali dolerite and one specimen of syenitic rocks. This Eu-depletion is interpreted to be related to the fractionation of feldspars during magmatic differentiation or formation of magma (partial melting) from source rock. Some considerations on the cause of absence and very small magnitude of Eu-depletion are also described.
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  • Relation between electronegativity and ratio of the heat of formation to the potential energy
    HARUO OHASHI
    1984 Volume 79 Issue 8 Pages 329-333
    Published: August 05, 1984
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.79.329
    JOURNAL FREE ACCESS
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    It is shown that the electronegativity (x) of spherical metal ion can be related to ratio of theheat of formation, -ΔH°298;, to potential energy (ne2/r) by the empirical equation:
    -ΔH°298/(ne2/r)=a/x-c+b,
    where a, b and c are empirical constants; n, e, and r represent the valence number, the charge on the electron, and the ionic radius, respectively. These results confirm that the thermo-chemical-electronegativity values for Hg2+and Pb2+ ions correspond to the one in a regular crystal field. By reason of these empirical relations the electronegativities of Ti3+, V3+ and Cr3+ in a regular octahedron are estimated to be 1.45, 1.6 and 1.65, respectively.
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  • On the qualification of rock mass
    Masahiro Abe
    1984 Volume 79 Issue 8 Pages 334-343
    Published: August 05, 1984
    Released on J-STAGE: August 07, 2008
    DOIhttps://doi.org/10.2465/ganko1941.79.334
    JOURNAL FREE ACCESS
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