古琵琶湖層群下部層序の再検討  [in Japanese] Stratigraphic reexamination for a lower part of the Kobiwako Group, central Japan  [in Japanese]

Access this Article

Search this Article

Author(s)

Abstract

琵琶湖周辺に分布する古琵琶湖層群は日本の鮮新-更新統として代表的な陸水成層として研究対象とされてきたが,近年になってその最下部層序の間違いが指摘されている.その間違いを修正するために,33の火山灰層の調査が行われ,広域テフラやそれぞれの対比の検討を行った.その結果,6層の火山灰層が対比され,それによって,最下部層序が確立された.また,修正された層序によれば,古琵琶湖層群はおよそ4.4 Maにこの地域の東部で形成がはじまり,この時代の地形的制約によって西部は遅れて堆積が開始されたことが明らかにされた.

The Plio-Pleistocene Kobiwako Group is a typical fluvio-lacustrine formation located at Lake Biwa, Japan. However, the stratigraphy of the lowermost part of this group contained inaccuracies. In this study, 33 tephra beds were examined to correct the stratigraphy and to investigate possible correlations among these beds and with other widespread tephras. As a result, six correlated tephra beds corrected the lowermost part of the group. A subsequent reassessment of the stratigraphy indicates that this group was formed at ca. 4.4 Ma in the eastern part of the area, and slightly later in the western part, due to constraints imposed by the terrain during this period.

Journal

  • The Journal of the Geological Society of Japan

    The Journal of the Geological Society of Japan 121(4), 125-139, 2015

    The Geological Society of Japan

Codes

  • NII Article ID (NAID)
    130005089839
  • NII NACSIS-CAT ID (NCID)
    AN00141768
  • Text Lang
    JPN
  • ISSN
    0016-7630
  • NDL Article ID
    026398521
  • NDL Call No.
    Z15-174
  • Data Source
    NDL  J-STAGE 
Page Top