The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
Volume 47 , Issue 567
Showing 1-4 articles out of 4 articles from the selected issue
  • Masao GORAI
    1940 Volume 47 Issue 567 Pages 481-498
    Published: December 20, 1940
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    Wutalienchih volcano( ?? ?? ?? ?? ?? ?? ) of North Manchuria is composed of a group of alkali-basalts, which contain about 5% of K2O., The essential constituents of these effusives are olivine, augite, anorthoclase, leucite, magnetite, titan-iron ore, and glass, plagioclase being almost excluded., Their average chemical composition is very similar to that of the world average minette, given by R., A., DALY., In these effusives, xenocrysts from granitic rocks, though not abundant, are universally distributed and in Shihlung lava ( ?? ?? ?? ?? ) which occupies the central part of this district, xenoliths of the same origin are occasionally found., While alkali-feldspars of these xenoliths and xenocrysts are largely resolved, and hornblende and biotite are also completely opacitized (and slightly resolved), quartz and plagioclase are only partly attacked., The materials assimilated in these effusives must be, therefore, in the main SiO2, Al2O3, Na2O, K2O., The ratio among CaO, MgO, and FeO+Fe2O3 in the average composition of these alkali-basalts, that are believed to be practically unaffected by assimilation, are compared with those of the Cenozoic basic effusives from·East Asiatic Province, which are considered to be not contaminated., It was found that the ratio is very similar to that of the average basalt of Chihsingshan volcano ( ?? ?? ?? ?? ?? ) in Central Manchuria., If we take, therefore, the average composition of Chihsingshan volcano as the composition of magmatic origin in the North Manchurian alkali-basalts under consideration, we can estimate the composition assimilated in the latter by constructing the variation diagram from the Chihsingshan average and the North Manchurian average., The graphical construction shows that the material assimilated has a trachytic composition rich in K2O., According to the observations recorded on the selective resorption of granitic rocks in basic magma and the melting phenomena of igneous rocks in the laboratory, the formation of trachytic liquid rich in K2O is possible in the comparatively earlier stage of resorption., The North Manchurian alkali-basalts are considered, therefore, to be formed by selective resorption of granitic rocks by basaltic magma which will be slightly more basic than the average Chihsingshan basalts., Lastly the geographical distribution of some effusives which are especially rich in K2O relative to Na2O is examined, as the result of which they are found to distribute only in the continental regions, but are absent from the oceanic regions.,
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  • Yosiyuki IWAYA
    1940 Volume 47 Issue 567 Pages 499-506
    Published: December 20, 1940
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    As shown in the geological map in the Japanese text the Tetori series in the surveyed area is faulted and thiust at some places, and intruded by granitic rocks at others., Its base is unknown because of the igneous intrusion into the basal part., The series may be divisible into six formations in descending order as follows : f) Ogamigo upper Cyrena and Plant bearing formation e) Okurodani sandstone and conglomerate formation d) Otaniyama upper Perisphinctes bearing formation c) Mitarashi middle Cyrena and Plant bearing formation b) Nonomata lower Perisphinctes bearing formation a) Ushimaru lower Cyrena and Plant bearing formation The occurrences of Perisphinctids and other marine shells in the two formations are discoveries made by the present research., These marine formations alternate with the non-marine ones and the latter yield plant fossils., Formarly OISHI claimed that the plant beds indicate one definite horizon in the Tetori series, but in fact they are distributed in various horizons from top to base as KOBAYASHI has already pointed out., As the opinion that the Jurassic period was a time of tranquility insofar as volcanism is concerned has been current among the Japanese geologists, the find of acidic tufflayers in the Ushimaru and Mitarashi formations are facts hitherto unknown.,
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  • Nobuo KURATA
    1940 Volume 47 Issue 567 Pages 507-516
    Published: December 20, 1940
    Released: April 11, 2008
    JOURNALS FREE ACCESS
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  • Teiichi KOBAYASHI, Tuneo HUKASAWA
    1940 Volume 47 Issue 567 Pages 517-519
    Published: December 20, 1940
    Released: April 11, 2008
    JOURNALS FREE ACCESS
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