The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
Volume 113 , Issue 8
Showing 1-5 articles out of 5 articles from the selected issue
Articles
  • Tsumoru Sagayama, Yaeko Igarashi, Tsutomu Kondo, Kotaro Kamada, Mitsuo ...
    2007 Volume 113 Issue 8 Pages 391-405
    Published: 2007
    Released: June 17, 2008
    JOURNALS FREE ACCESS
    14C dating, sedimentary facies analysis, volcanic ash analysis, pollen analysis, diatom analysis and radiolaria analysis were carried out to clarify the Quaternary stratigraphy on the 150 m core, drilled in 1981, in the campus of Hokkaido University, central part of Sapporo. Our investigation leads to the following conclusions. 1) The core is divided into nine formations, HU-1 to HU-9. The HU-1 to the HU-3 in 150−75 m depth are correlated to the Shimonopporo Formation of the early to middle Pleistocene, the HU-4 and the HU-5 in 75−35 m depth to the Momijidai Formation of the late Pleistocene, the HU-6 in 35−34 m depth to the Konopporo Formation of the late Pleistocene, the HU-7 and the HU-8 in 34−7.8 m depth to the Sapporo Fan Deposits of the late Pleistocene, the HU-9 in 7.8−0 m depth to the Holocene. 2) Identification of the cold stage and warm stage in the HU-4 and HU-5, last interglacial stage deposits, causes the possibility of accurately comparing to the deposits in the southernmost part of Ishikari Depression. 3) Peat bed intercalated in 130 m depth, 119 m below sea level, in the correlative of Shimonopporo Formation of the core is correlated to the peaty deposits which exist at about 110 m below sea level in the nearby two boreholes, and peat beds which intercalated under the Ishikari Coastal Plain within the range from 102 m to 126 m below sea level in the correlative of the Shimonopporo Formation.
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  • Jun-ichi Tazawa, Yoshiyuki Hasegawa
    2007 Volume 113 Issue 8 Pages 406-416
    Published: 2007
    Released: June 17, 2008
    JOURNALS FREE ACCESS
    A Permian fusulinoidean fauna, described from the Takagami Conglomerate of the Atagoyama Formation in the Choshi area, central Japan and consisting of 15 species in 10 genera, is taxonomically restudied and compared with those of the South Kitakami Belt (South Kitakami Mountains) and the Kurosegawa Belt (central Kyushu). Consequently the Choshi fauna resembles the Permian fusulinoidean faunas from both the South Kitakami and Kurosegawa Belts, although it is closer to the latter than the former. This result suggests a tectonic continuity between the South Kitakami Belt and the Kurosegawa Belt. The Upper Permian Atagoyama Formation and the unconformably overlying Lower Cretaceous Choshi Group in the Choshi area belong to the Kurosegawa Belt in the Kanto Mountains, and they are located at about the middle of the continuous South Kitakami-Kurosegawa Belt.
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  • Masaki Matsukawa, Makiko Fukui, Kazuto Koarai, Tsutomu Asakura, Hiromi ...
    2007 Volume 113 Issue 8 Pages 417-437
    Published: 2007
    Released: June 17, 2008
    JOURNALS FREE ACCESS
    The Tetori Group is distributed in the Hida-Furukawa area. There are diverse opinions about the stratigraphy of the group. So, we restudied the stratigraphy of the group. The group can be divided into six formations: the Tanemura, Numamachi, Sugizaki/Tochio, Taie and Inagoe in ascending order. The geological map of the area was revised to show the distribution of these six formations. These formations are suggested the environments of alluvial fan to shallow marine, shown by deposits transported from the eastern hinterland and fossil evidence. Ammonite indices suggesting Hauterivian to Barremian age occur in the Inagoe Formation. This shows the evidence of the third marine transgression in the Tetori Group. As marine bivalves including inoceramids occur in the Sugizaki Formation as well, two marine transgressions can be recognized in the Tetori Group in this area. Consequently, three sequential marine transgressions: Bathonian to Oxfordian, Tithonian to Berriasian, and Hautervian to Barremian, can be recognized in the Tetori area.
    In the eastern part of the Heilongjiang, China, two marine transgressions, the first from late Oxfordian to Volgian (=Tithonian to early Berrriasian) and the second from Barremian to Aptian, are recognizable. Therefore, these marine transgressions in China correspond to these in the Tetori area.
    Occurrence of common marine bivalve species and related ammonite species suggests the same realm for both the eastern part of the Heilongjiang, China and the Tetori area, Japan, during Hauterivian to Barremian time. These faunal compositions are different from those of areas in the southwest of Japan influenced by currents from low latitudes. This supports the idea that a peninsula of land was present between both the Tetori area and areas in southwest of Japan. Thus, both areas of the eastern part of the Heilongjiang and the Tetori area were influenced by current from the high latitude.
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  • Minoru Utada
    2007 Volume 113 Issue 8 Pages 438-453
    Published: 2007
    Released: June 17, 2008
    JOURNALS FREE ACCESS
    The Neogene formations are distributed in the central San'in district facing the Sea of Japan. They contain a large amount of felsic to andesitic volcanic and volcaniclastic materials. Alteration of these materials was investigated by means of X-ray diffractometry using Cu-Kα radiations. Five types of alteration are discriminated: diagenetic, regional intermediate, hornfelsic, hydrothermal alteration, and weathering.
    Diagenetic alteration is characterized by authigenic zeolites and classified into 4 zones: fresh glass, clinoptilolite-mordenite, (heulandite)-analcime, and laumontite zones. These zones are distributed in ascending order roughly according to stratigraphy. Regional intermediate alteration is characterized by smectite-chlorite series clay minerals. It is classified into 3 zones: the smectite, the smectite-chlorite mixture, and chlorite zones. Hornfelsic alteration is characterized by biotite and/or hornblend in addition to assemblage of the chlorite zone of regional intermediate alteration. However, this alteration is very rare in this district. Hydrothermal alteration is divided into two types by mode of occurrence of alteration minerals. One is the vein-type in which alteration minerals occur in veins and another is the layer-type in which alteration minerals occur as stratified layers showing zonal distribution. Detail description on weathering was omitted in this paper. Diagenetic alteration is overlapped by other types of alteration in various horizons. The extent of overlapping is different in each areas.
    The magnetic susceptibility of altered rocks was measured. There are significant differences among altered rocks of each type of alteration.
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