The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
Volume 55, Issue 646
Displaying 1-3 of 3 articles from this issue
  • Tokio Shikama, Kunio Kobayasi
    1949 Volume 55 Issue 646 Pages 65-71
    Published: September 20, 1949
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    There have been many discussions about the glaciation of Japan and now there is a consensus of opinion that in the Central Japan the mountains have been heavily glaciated, though it is possible that some features of the summits with elevations of about 3000m owe their origin to glacial scuipture., However no elaborate correlation of the Ice Age of Japan with the 4 glacial ages of Europe and America has yet been established., After studying the diluvial chronology of the Eustern Asia and Japan, the senior auther had once published his opinion that there were 3 cold ages since the Villafranchian each referred to Pd, dlII., and du, from the argument based on the palaeontological evidences., The last 2 ages may correspond to Riss Ice Age or Barbour's "Riss-Wurn Double Glacial Age., " The Junior auther undertook the study of the topographical evolution of the Hida Range and the senior auther that of the Kiso Range., In this paper they have demonstrated that the Hida and the Kiso Ice Ages might be synchronous and referred to duI stage and also to Riss or Riss-Wurm Double Glacial Ages from the correlation based on the geomorphological and stratigraphical evidences., It appears that the growth of the glacier originated from the emergence of the Pd erosion surface above the snow line by a rapid elevation during dlII-duI stage., However the reduction of climatic temperature was small and the glaciation in the Hida and the Kiso Ranges during the upper Pleistocene is attributed to an increased elevation of land rather than to a reduction of climatic temperature.,
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  • Sadakatu Taneda
    1949 Volume 55 Issue 646 Pages 72-76
    Published: September 20, 1949
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    The quantitative studies were made on magnetite of many volcanic rocks, varyingni siliea content from 50% to 72%, and the significance of magnetite in the course of magnetic evoluation was certified., In the end it is concluded that the amount of magnetite is related to the chemical composition of other rock-forming minerals, for example the En:Fs ratio in the rhombic pyroxene crystallized from magma along with the magnetite, and that the characteristic of the hornblende andesite largely due to the promoted crystallization of magnetite through the whole stages of crystallization of phenocryst, microphenocryst and groundmass or through one or two stages of them., It is the most notable that the ferromagnesian minerals occurring in the groundmass are rather poor in Wo and Fs contents in their pyroxene components comparing with the phenocrystic ones.,
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  • Haruo Shirozu
    1949 Volume 55 Issue 646 Pages 77-83
    Published: September 20, 1949
    Released on J-STAGE: April 11, 2008
    JOURNAL FREE ACCESS
    The manege deposits of the Ioi Mine are deposited along a contact plane betweenq uartzite and sandy slate in the Chichibu Palaeozoic formation which is composed of alternations of quartzite and slate., The deposite consist of the two groups of complicated bedded-veins., The western ore body of Prof., T., Yoshimuras Ioi Type deposit, includes large quantity of manganese dioxide ore., The eastern ore body has the noticeable shape as presented in Fig., 1, being composed mainly of hausmannite, manganese carbonates and manganese silicates., Hausmannite was confirmed by chemical analysis (Table 1) and X ray powder photographs (Tabie 2, No., 1)., The hausmannite occured allo abundantly in the brown earthy spots as shown in the X ray powder photographs (Table 2, No., 2), in the manganese carbonate ore of light pinkcolor., In this deposits there are found such another numerous minerals as follows; pyrrhotite, ala-bandite, arsenopyrite, marcasite (?), pyrite, manganosite, quartz, chalcedony, opal, manganbrucite, pyrochroite (?), manganite (?), galaxite, rhodochrosite, mangancalcite, barite, apatite, adularia, spessartine, tephroite, alleghanyite, manganhedenbergite, rhodonite, dannemorite, mangan tremolite-actinolite, manganphlogopite, chlorite, and penwithite.,
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