上越沖海底メタン湧出地域の現世底生有孔虫群集 Distribution of Recent Benthic Foraminifera in the Methane Seepage Area off Joetsu in the Eastern Japan Sea

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 Benthic foraminiferal assemblages of surface sediments were studied in the methane seepage area in the eastern margin of the Japan Sea to identify the effects of methane seep on foraminiferal distribution. Samples were collected from three areas, each including a methane-seep site. Their water depths range from 882 m to 1006 m in the Japan Sea Proper Water. At the methane-seep sites, there were significantly fewer living (stained) foraminifera than at other sites, and ratio of agglutinated foraminifera is small, showing the dominance of calcareous forms. Planktonic foraminifera are very abundant at seep sites. These suggest higher alkalinity at the sediment-water interface of the seep sites.<br> <i>Cassidulina norvangi, Pseudoparrella takayanagii and Bolivina decussata</i> increase while <i>Trochammina pygmaea, Thalmannammina parkerae, Lagenammina tublata, Reophax</i> cf. <i>dentaliniformis, Saccammina huanghaiensis</i>, etc., decrease at the seep sites. These species are usually common in the Japan Sea Proper Water. Their changes in abundance seem, in part, to relate to alkalinity because the former taxa are calcareous foraminifera and the latter are all agglutinated. There are fewer <i>Bolivina pacifica, Stainforthia fusiformis, Nonionella globosa</i>, and <i>Globobulimina auriculata</i> in the living population at the seep sites, although they are abundant in the total (living + dead) population. These taxa are well-known infauna and can survive in oxygen-depleted environments. This discrepancy may be explained by the mode of methane seepage; the present seeping is not severer than in the near past and is transient at each seep site. The effects of the present methane seeps extend only to less than 40-50 m from each methane-seep site.

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  • 地學雜誌

    地學雜誌 118(1), 136-155, 2009-03-25

    公益社団法人 東京地学協会

参考文献:  45件中 1-45件 を表示

被引用文献:  2件中 1-2件 を表示

各種コード

  • NII論文ID(NAID)
    10030364941
  • NII書誌ID(NCID)
    AN00322536
  • 本文言語コード
    JPN
  • 資料種別
    ART
  • ISSN
    0022135X
  • NDL 記事登録ID
    10232749
  • NDL 雑誌分類
    ZM41(科学技術--地球科学)
  • NDL 請求記号
    Z15-169
  • データ提供元
    CJP書誌  CJP引用  NDL  J-STAGE 
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