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 39, Issue 5
Displaying 1-5 of 5 articles from this issue
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  • The diversity of Tanohata granitic mass, northern Kitakami mountains, Iwate Prefecture
    Kiyohiko Ishii, Tadamasa Sendo, Yoshio Ueda
    1955 Volume 39 Issue 5 Pages 177-189
    Published: October 01, 1955
    Released on J-STAGE: March 18, 2008
    DOIhttps://doi.org/10.2465/ganko1941.39.177
    JOURNAL FREE ACCESS
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    The Tanohata granitic mass, northern Kitakami mountains, Iwate Prefecture, shows various rock facies. The granitic mass is classified into six types by the rock facies as follows.
    1) Moichi type - hornblende biotite granodiorite
    2) Hagiu type - hornblende biotite granodiorite
    3) Otomo type - biotite granodiorite
    4) Kawaguchi type - biotite hornblende granodiorite
    5) Otanabe type - hornblende biotite quartz monzonite
    6) Shimoakuka type - hornblende biotite quartz monzonite
    It is concluded that the Tanohata granitic mass is the composite one, being the product of successive intrusions of the above-mentioned types and the order of intrusions is as follows, that is, at first the Kawaguchi body occurred during the last period of orogeny, the second is the Moichi and then the Hagui and the Otomo intruded successively. The Otanabe erupted in the north contemporaneously with the Otomo, and at last the Shimoakuka occurred as a separated minor body intruding into the Otanabe with very sharp boundary between both of them.
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  • A petrographical note on the welded tuff around Onikôbe caldera
    Yosio Katusi
    1955 Volume 39 Issue 5 Pages 190-194
    Published: October 01, 1955
    Released on J-STAGE: March 18, 2008
    DOIhttps://doi.org/10.2465/ganko1941.39.190
    JOURNAL FREE ACCESS
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    The Onikobe caldera has been noticed by H. Kuno to be a raldera of Krakatoan type of H. Williams. Very recently, M. Minato in cooperation with K. Yagi, found and identified beyond doubt a kind of welded tuff widely developed around the Onikobe caldera. This short note is a petrographical description of the specimens brought back by M. Minato from the outcrop of that welded tuff near Akakura, Miyagi Prefecture.
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  • Corundum and andradite from Okita, Daito-machi, Iwate Prefecture
    Shuzo Hasegawa
    1955 Volume 39 Issue 5 Pages 194-203
    Published: October 01, 1955
    Released on J-STAGE: March 18, 2008
    DOIhttps://doi.org/10.2465/ganko1941.39.194
    JOURNAL FREE ACCESS
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    Andalusite-hornfels, sillimanite-hornfels and skarn were formed by contact metamorphism of granitic intrusion into Paleozoic formation. Corundum occurs in sillimanite-hornfels as a porphyrobrastic crystal, about 5mm in diameter, associated closely with orthoclase. The measured specific gravity is G4 ?? 180=3.963 and the indices of refraction are ω=1.768, ε=1.761, ω-ε=0.007. The result of chemical analysis shows in Table 2 -(2). Andradite, essential constituent of skarn, occurs as yellowish brown aggregate. The specific gravity is G4 ?? 160=3.831 and the index of refraction measured by minimum deviation method is np =1.8888. From the chemical analysis shown in Table the formula is given as (Ca2.88 Mnu0.07 Fe0.05) 4.00 (Al0.34 Fe1.85)1.99 Si2.96 O11.85, and the molecular percentages of endmembers are calculated as And 91.9, Gr 4.1, Alm 1.7, Sp 2.3 mol.%.
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  • Mechanical grain analysis of sandstones of the Shinjo group. (I)
    Nagasawa area in the eastern margin of the Shinjo basin
    Iwao Kato, Masahiro Abe
    1955 Volume 39 Issue 5 Pages 204-215
    Published: October 01, 1955
    Released on J-STAGE: March 18, 2008
    DOIhttps://doi.org/10.2465/ganko1941.39.204
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    The purpose of this study is to produce quantitative data on the clastic sediments belonging to the upper formations of the Neogene, the Shinjo group, developed in the Shinjo oil-field. The units selected for analysis are the lignite-bearing formations, demarcated by the characteristic sandstone facies, exposed along the Oguni river near Nagasawa in the eastern margin of the basin.
    Four types are recognized as the result of the mechanical analysis (median diameter, coefficient of sorting, standard deviation, skewness, and kurtosis) and these types, A, B, C and D, are practically correlated with the Mitsumori, Sakegawa-Yamuke, Shimizu, and Izumikawa formations respectively. It is worthy to note that among these four types a clear line is drawn between the former two types, A and B, and the latter two types, C and D, and also it clearly corresponds the marker bed (K4) at the basal part of the Shimizu formation traceable along the major parts of the marginal part of the Shinjo basin.
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  • The iron beach sand deposits along the coast between Mukawa and Horobetsu, Iburi Province, Hokkaido (II)
    Hokuichiro Ohmachi, Yoshio Suzuki, Akira Hayakawa
    1955 Volume 39 Issue 5 Pages 216-222
    Published: October 01, 1955
    Released on J-STAGE: March 18, 2008
    DOIhttps://doi.org/10.2465/ganko1941.39.216
    JOURNAL FREE ACCESS
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