グリーンランドの大陸氷は,エオセーンとオリゴセーン時代に存在した
James S Eldrett1, Ian C Harding, Paul A Wilson
1School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, European Way, Southampton SO14 3ZH, UK.
Nature
|February 9, 2007
まとめ
初期のグリーンランドの氷河は,以前考えられていたよりも2千万年前に存在し,エオセンからオリゴセンの移行期に存在していた. アイスラフトの破片からの証拠は,海氷ではなく氷河氷,運搬された堆積物を示唆しています.
科学分野:
- 古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは
- パレオセアノグラフィー
- 地質学 地質学 地質学
背景:
- エオセーン・オリゴセーン移行 (55~2300万年前) は,氷のない世界から南極の氷床のある世界への地球規模の気候変動を大きく変えた.
- 北半球の初期の氷河の歴史は依然として論争の的だ.
- 以前の理解では,北半球の氷河化は,新しい発見によって示されるよりも遅かったと示唆されていました.
研究 の 目的:
- 北半球における初期の氷河期の時期と起源を調査する.
- エオセンの終わりからオリゴセンの初期にかけての氷河活動の証拠を提供する.
主な方法:
- マクロスコープの落下石を含む,地層学的に広範囲の氷河川の破片の分析.
- ノルウェー・グリーンランド海から採取したサンプルの堆積物分析.
- 堆積物の年代は,およそ3800万年から3000万年前の時期とされています.
主要な成果:
- エオセンの終わりからオリゴセンの初期 (38-3000万年前) の氷河移動の兆候となる氷河の破片の発見.
- 氷の浮遊物資の潜在的な源泉として東グリーンランドを特定する.
- 証拠によると,グリーンランドに孤立した氷河が存在したのは,これまで記録されていたよりも約2千万年前だという.
結論:
- この発見は,北半球氷河期に関する既存のタイムラインに異議を唱えている.
- グリーンランドには,気温と大気中のCO2濃度が大幅に上昇した時期に,孤立した氷河が存在していた.
- この研究は,初期のケノゾイク期の気候動態と氷床の形成の理解に貢献します.
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