²³⁰Thを用いたチリ沖中緯度域における第四紀後期生物起源粒子フラックス変動

• 原田 尚美

  （独）海洋研究開発機構地球環境変動領域

• 川上 創

  （独）海洋研究開発機構むつ研究所

• 福田 美保

  （独）海洋研究開発機構地球環境変動領域 筑波大学大学院生命環境科学研究科

• 宮下 航

  高速炉技術サービス株式会社

• 松本 剛

  琉球大学理学部物質地球科学科

書誌事項

タイトル別名

• ²³⁰Th-normalized Fluxes of Biogenic Components from the Central Chilean Margin during the Late Quaternary
• ²³⁰Thを用いたチリ沖中緯度域における第四紀後期生物起源粒子フラックス変動
• ² ³ ⁰ Th オ モチイタ チリオキ チュウ イドイキ ニ オケル ダイシキ コウキ セイブツ キゲン リュウシ フラックス ヘンドウ
• 230Th-normalized Fluxes of Biogenic Components from the Central Chilean Margin during the Late Quaternary

抄録

 Throughout geologic time, variations of atmospheric CO₂ partial pressures (pCO₂) have been associated with climate change. During glacial periods, increased productivity and an efficient biological pump in the North Pacific, equatorial Pacific, and Southern Oceans may have contributed to low atmospheric pCO₂. Furthermore, changes in global ocean ventilation would have been considered to be among the most effective controllers of variations of atmospheric pCO₂ glacial-interglacial time scale. However, there is still some controversy as to whether ventilation was effective everywhere during glacial periods, and whether intensification of marine productivity resulted in a decrease of atmospheric pCO₂. Resolving this controversy requires more data from many regions regarding temporal changes in past export fluxes of biogenic materials, especially in the upwelling area, where active ocean ventilation and biological production are observed. The aim of this study is to identify changes in the ²³⁰Th-normalized export flux of biogenic components commonly used as proxies for paleoproductivity—namely total organic carbon (TOC), calcium carbonate (CaCO₃), biogenic opal (Si_OPAL), and opal and CaCO₃ ratio (Si_OPAL/CaCO₃)—as recorded in a sediment core from 36°S off the central–south Chilean coast. The ²³⁰Th-normalized fluxes of biogenic components were low from 22,000 to 15,000 calendar years before the present (cal yr BP), indicating reduced primary productivity. From 13,000 to 10,000 cal yr BP, the ²³⁰Th-normalized flux of biogenic components increased, thereafter dropping between 8000 and 5000 cal yr BP, and again increasing slightly in the late Holocene (< 5000 cal yr BP). The changing ²³⁰Th-normalized fluxes of biogenic components are linked to upwelling activity, which was at its maximum during the late deglaciation during the past 22,000 yr. The high fluxes off the central–south Chilean coast might in part be not only due to enhanced coastal upwelling but also related to enhanced upwelling at higher latitudes of the polar frontal zone in the entire Southern Ocean, which would be related to the north-south migration of Southern Westerly Winds.

収録刊行物

• 地学雑誌

  地学雑誌 121 (3), 555-569, 2012

  公益社団法人 東京地学協会

キーワード

• チリ沖中央部
• 生物起源粒子
• 基礎生産
• LGM
• 最終融氷期
• トリウム230

詳細情報

• CRID: 1390282679213438080
• NII論文ID: 10031146393
• NII書誌ID: AN00322536
• DOI: 10.5026/jgeography.121.555
• ISSN: 18840884
• ISSN: 0022135X
• NDL書誌ID: 023869935
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I023869935
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• 抄録ライセンスフラグ: 使用不可