池ノ原・塩坪両砂岩層の粒度分析と鉱物分析について

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書誌事項

タイトル別名
  • On the Mechanical Analyses of the Ikenohara Sandstone and the Shiotsubo Sandstone Members, in the western Area of the Aizu Basin, Fukushima Prefecture, Japan
  • 池ノ原・塩坪雨砂岩層の粒度分析と鉱物分析について
  • イケ ノハラ シオ ツボ ウ サガンソウ ノ リュウド ブンセキ ト コウブツ ブンセキ ニ ツイテ
  • イケ ノハラ シオ ツボ リョウ サガンソウ ノ リュウド ブンセキ ト コウブツ ブンセキ ニ ツイテ

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説明

The intimate stratigraphical relationship, conformable in the central area but uncofnormable in the northeastern and southwestern borders, has been recognized by the writers, between the Yamato and the Yamasato groups. The Ikenahara coarse sandstone member (upper Miocene) is the lowest one of the Yamato group, and the Shiotsubo sandstone member (upper Miocene) is the uppermost one of the Yamasato group. To clarify the mechanism which caused the relationship between the both groups and the sedimentary conditions of both sandstone members, the writers carried out the grain size and mineral analyses. The results are as follows; 1) The Ikenohara sandstone member contains bipyramidal quartz in remarkably large quantities, and various igneous mafic minerals-hypersthene, augite and hornblende-in small quantities, and is characterized by coarse Ac and Bb grain sizes. The Shiotsubo sandstone member contains large quantities of biotite and glassy volcanic fragments, and is characterized by medium to fine Cd-e grain sizes. 2) The grain size pattern of the Ikenohara sandstone member affords several varieties. It is characterized by an uniform constitution in the northern area, by deltaic environmental patterns in the northeastern area, and by lagoonal environmental patterns in the southern and central areas. On the other hand, variation of grain size pattern is scarcely recognized in the Shiotsubo sandstone member. The Ikenohara coarse sandstone member has several different environmental patterns; i.e. deltaic in the northeastern area, inletic in the northern area, tidal inletic in the central area and lagoonal in the southern area. The Shiotsubo sandstone member has an uniform environmental pattern which shows a neritic, shallow marine condition. 3) The remarkable differences in grain size pattern and mineral composition between both sandstone members suggest a sudden change of palaeogeographical conditions of the sedimentary basin and the hinterland during the sedimentation. This change may be closely related to the acidic volcanisms (Iitani liparitic volcanics etc.), and to the tilting movements which trended from NE to SW in the northwestern area and from SW to NE in the southeastern area of the Aizu Basin, This change might have caused the differentiation of the sedimentary basin.

収録刊行物

  • 地球科学

    地球科学 1958 (38), 1-12, 1958

    地学団体研究会

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