The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
Volume 60 , Issue 704
Showing 1-5 articles out of 5 articles from the selected issue
  • Akira HATAKEYAMA
    1954 Volume 60 Issue 704 Pages 171-184
    Published: May 25, 1954
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    1) The stratigraphic succession of the formation in the eastern part of Honjo Basin, Akita Prefecture, was established by the writer., The formations are comformable throughout the area., They are described from upper to lower as follows: Isizawagawa group Minaminomata formation: alternation of fine sandstone and gray mudstone (containing Sagarites) in the lowermost part (80m., + in thickness) Tate formation (about 450m., in thickness): black mudstone (containing Sagarites and smaller foraminifera) Toridame formation (250-400m., in thickness): hard mudstone and siliceous mudstone (containing Sagarites, fish bone and scale) Simogo group Sugota formation (100-200m., in thickness): conglomerate and sandstone (containing Sagarites, smaller foraminifera, mollusca, plants, lignite and silicified woods) Hatamura formation (80-200m., in thickness): green tuff and tuffaceous sandstone (containing plants, lignite and silicified woods) Kanotume formation (320-400m., in thickness): andesite lava, agglomerate and tuff Hisumiyama group Oyana formation (200-350m., in thickness): lithoiditic rhyolite tuff and tuffaceous shale (containing plants and lignite) Yamauti formation (300m., in thickness): andesite lava, agglomerate and tuff breccia 2) Hisumiyama and Simogo groups and the Toridame, Tate and Minaminomata formations in the area may be correlated approximately to the Takasegawa tuff beds, Onnagawa shale beds, Funakawa shale beds and Hosogoe shale beds of K., MURAYAMA (1934) respectively., 3) Some components of Aniai flora (Picea, etc., ) are contained in Oyana formation, and of Daizimaian flora (Liquidambar formosana, etc., ) in either Hatamura or Sugota formation., Sugota formation includes mollusca (Patinopecten kimurai, Chlamys cfr., kaneharai, etc., ) and smaller foraminifera (Lagenidae, Buliminidae, etc., ) which are characteristic to the formation., 4) Two similar cycles of volcanic activities, which begin with the eruption of andesite and end with the eruption of rhyolite, are recognized in both Hisumiyama and Simogo group., The intense volcanic activities are also associated with the deposition of the lower part of Sugota formations, as well as with the upper part of Minaminomata formation.,
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  • Yoshio KATSUI
    1954 Volume 60 Issue 704 Pages 185-191
    Published: May 25, 1954
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    In this paper, the chemical compositions of the lavas from the Chokai volcanic zone along the inner are of the Japanese Islands is described., The Chokai volcanic zone includes volcanoes of Oshima-oshima, Iwaki, Kanpu, Chokai, Gassan and Yudonosan, which are characterized by the common occurrence of hornblende in lavas., The lavas vary from augite-olivine basalt to hypersthene-biotite-hornblende dacite and range from 48., 89 % to 66., 98 % in silica content., The most outstanding chemical characteristic of the lavas is the richness in alkalies, especially in K2O, also the undersaturation in sillica in most of basic lavas., The alkali-lime index is about 60, indicating an alkalic content greater than that of the average Japanese effusive rocks (63., 7)., The ration of Fe2O3/FeO, total FeO/MgO, CaO /Na2O + K2O and Na2O/K2O are representative of those of hornblende-bearing lavas from Japan., Qz and at-alk of NIGGLI'S values are low, and c-(al-alk), k and mg are high, while normative Or, En and Wo are high, and Q and An are low., Such chemical characteristics are closely related to modal compositions., A striking similarity in the chemical characteristics is found between the lavas of the Chokai and the Daisen zones, showing a contrast to those of the Nasu zone and Izu-Hakone region., It may be concluded that lavas of the Chokai zone have an intermediate character between the extremely calcic rock suite of the Nasu zone and alkalic rock suite of the Circum-Japan Sea province, not only from their geographical distributions but also from their petrographical characteristics.,
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  • Keiji NAKAZAWA, Tsunemasa SHIKI
    1954 Volume 60 Issue 704 Pages 192-201
    Published: May 25, 1954
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    The Paleozoic rocks which occur in the Miharaiyama district belong to the Minamitani group., They are correlated with the rocks of Kuma series (Upper Permian), which are typically expose in Kumamoto Pref., The Minamitani group contains special deposits such as the so-called Yasuba conglomerate., The Mesozoic Miharaiyama group is correlated with the lower part of the Inai series and is considered Scythian in age., It is subdivided as follows: Gannosudani formation G3 bluish grey siltstone -200m G2 bluish grey sandstone -80∼95m G1 conglomerate-50∼80m Niikuradani formation N2 bluish grey sandstone -30∼60m N1 basal conglomerate -15∼30m Minamitani group (Upper Permian) The Niikuradani formation contains no fossils, but the Gannosudani formation, especially G2 is rich in fossils which are listed below., G3: Nuculana sp., Myophoria aff., laevigata G2: Neobakevellia kambei M., S., M., aff laevigata (abundant) Neob., kambei sakaigawensis M., S., Nuculana sp., Rhynchonella sp., Terebratula? sp., etc., (rare) An unconformity was discovered between the Miharaiyama group and the underlying Paleozoic rocks., The Lower Triassic formations in Japan are local and very limited in occurrence., They are generally jammed into others formations by faults., Previously, the disconformable relation of the Lower Triassic with the Upper Permian Series (≒Kuma series), had beenknown only in the Kitakami Mountains, Miyagi Prefecture., The discovery of the unconformity mentioned above may be important in the study of the late Paleozoic crustol movement in Japan.,
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  • Kei OSHITE
    1954 Volume 60 Issue 704 Pages 202-211
    Published: May 25, 1954
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    This is a report of the qualitative and quantitative study of diatoms found in bottom-deposits of the Mutsu Bay, the northernmost bay of Honsyu, Japan., Samples were collected at 25 stations in the bay (fig., 1) in May, 1953., Table 2 and fig., 2 show the number of diatom-cells included in one gram of samples (dry) from each station., Table 2 suggests the following conclusions : (1) The factor which controls greatly the quantity of diatoms in the deposits is the resistance of cells to destruction by solution and current action., (2) Thala'nema, Melosira and Coscinodiscus are abundant in the deposit whereas Chaetoceros, Rhizosolenia, Skeletonema and Asterionella are almost entirely absent, though in plankon the latter very abundant in this bay., (3) The diatoms on the bottom of this bay are rather uniform in quality but not in quantity.,
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  • Yutaka SAITO
    1954 Volume 60 Issue 704 Pages 212
    Published: May 25, 1954
    Released: April 11, 2008
    JOURNALS FREE ACCESS
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