Journal of Geography (Chigaku Zasshi)
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
Volume 90 , Issue 6
Showing 1-6 articles out of 6 articles from the selected issue
  • Minoru TAMURA
    1981 Volume 90 Issue 6 Pages 369-392
    Published: December 25, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    In addition to many works on this problem which have been done for about forty years, recent studies in Japan, Korea and SE Asia were introduced. These results were sum marized from the view points of taxonomy, age correlation and environment. The faunas are divisible into three (Neocomian, Up. Neocomian Low. Albian and Up. Albian-Turoni-an) and brief explanations on them were given.
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  • Yoshiki OKA, Akira SANGAWA
    1981 Volume 90 Issue 6 Pages 393-409
    Published: December 25, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    Geographic Outline AWaji Island lies from NE to SW, dividing the east Inland Sea. The central range running in same direction continues to the Rokko mountains which are thought to have been elevated by crustal movement in Pleistocene (Rokko Movement). In the southern part of this island is the Yuzuruha mountains of Cretaceus sedimentary rocks which are a part of the series of mountain ranges on the north of Median Tectonic Line (MTL). In the plains of this island are seen hills of Pliocene deposits (the Awaji group) elevated from below the bottom of the Inland Sea.
    Purpose of Study The authors intended in this study to make clear the process of the formation of the east Inland Sea and Awaji Island. In order, they carried out the investigation on following points :
    1. Relation between the Miocene deposits and the age of the formation of the erosion surface on the mountains in the north.
    2. Sedimentary process of the Awaji group.
    3. Faults and deformation of the Awaji group.
    Result of study The results obtained are as follows :
    1. The morphology of the basement rocks (granitic rocks) in the north had been already gentle and undulating before the Kobe group deposited, caused by the Miocene transgression. The thickness of it reached a few hundreds meter in the north, but after regression the Kobe group was erosed down to basement. The mountains in the north were flattened again in this age.
    2. In Pliocene time, the area of the east Inland Sea depressed and deposited the Awaji group of gravel, sand, lacustrine silt and clay. In early stage, the lake began to be supplied with sand, and gravel from the area to the north of the island. In last stage, rivers originated to the south of MTL carried gravel (Goshiki-hama gravel) over MTL. to the lake.
    3. Goshikihama gravel is supposed to be contemporaneous with the Uchihata gravel, which is the lowest of the Osaka group (Yoshiki OKA 1978). The lower part of the Awaji group is suggested to be older than the Osaka group.
    4. The thickness of the Awaji group reaches 800 meter in the north and 300 meter or more in the middle part of the island. It indicates the depression of the Inland sea in Pliocene time.
    5. The fault movement in this island took place after the sedimentation of the Awaji group. Reverse and transcurrent faults by E-W compression have been discriminative since the middle of Pleistocene age.
    6. The faults can be divided, by strike, into three types, as follows :
    Type I (N60°E) The faults of this type caused the uplift of the Yuzuruha mountains in the south.
    Type II (N-SNE-SW) This type of faults caused the uplift of the central range of the island.
    Type III (N20°W) This type of faults are active reverse faults cut through the main range of the island.
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  • Committee Of History Of Japanese Earth Sciences
    1981 Volume 90 Issue 6 Pages 411-423
    Published: December 25, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
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  • Teiichi KOBAYASHI
    1981 Volume 90 Issue 6 Pages 424-432
    Published: December 25, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
    The biostratigraphy of the Khingan-Sungari area in Northeast China was greatly advanced very recently by Chinese geologists and palaeontologists. With the discoveries of Lower, Middle and Upper Cambrian and various Ordovician fossils it is now warranted that the Mongolian geosyncline was extended through the area already at the beginning of the Palaeozoic era. The silurian and later Palaeozoic sequence and its local variation are summarized and shown in two tables.
    With reference to the geology of neighbouring areas the history of this part of the geosyncline is discussed. The intrageosynclinal vulcanism, mostly basic to intermediate, was often repeated there. During the Permian period sea retreated so extensively that the area turned out land completely by the end of the period. Land plants mostly of the Angara flora and Palaeomutela and other naiads are widely distributed there in the continental Upper Permian deposits. No Lower and Middle Triassic formation is as yet known from the area. In the eastern extension of the Lesser Khingan range in the Soviet Union, however, the marine Permian formation is overlain by the Skytic and Anisic formation conformably or disconformably.
    Near the eastern border of Province Chilin as well as in East Transbaikalia the folded mountains of older rocks are overlain by the marine Upper Triassic formation with marked discordance. These Permian and older formations are widely intruded by the Permo-Triassic granites. Therefore the Mongolian orogenic zone is definitely younger than the Variscan or or Hercynian mountains of Europe. It is now well ascerained that its architecture was completed at about the same time with the Triassic Akiyoshi mountains in Japan.
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  • [in Japanese]
    1981 Volume 90 Issue 6 Pages 433
    Published: December 25, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
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  • S. MAEDA
    1981 Volume 90 Issue 6 Pages Plate1-Plate2
    Published: December 25, 1981
    Released: November 12, 2009
    JOURNALS FREE ACCESS
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