ダイアトムや氷河川の破片から,北極海氷が存在した証拠が示されている
Catherine E Stickley1, Kristen St John, Nalân Koç
1[1] Department of Geology, University of Tromsø, N-9037 Tromsø, Norway [2] Norwegian Polar Institute, Polar Environmental Centre, N-9296 Tromsø, Norway.
Nature
|July 17, 2009
まとめ
北極の海氷は,約4750万年前,エオセンの中期に現れた. この研究は,化石ダイアトムとクォーツ粒子の分析を使用して,初期の海氷の形成を確認し,陸上の氷と区別しました.
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
- 海洋地質学 海洋地質学
背景:
- アイス・ラフト・デブリ (IRD) の記録は,北極の氷が中期エオセンの頃から存在することを示唆しているが,海氷と陸上の氷の区別はできない.
- 氷河氷とは異なる気候フィードバックメカニズムと地球規模の影響があるため,海氷と氷河氷の区別は極めて重要です.
- 以前のエオセンの中期の北極海氷に関する仮定には,包括的で定量化された証拠が欠けていた.
研究 の 目的:
- 中エオセンの北極海氷の存在と時期を明確に確立するために.
- 氷河船の破片 (IRD) の輸送メカニズムを区別する.
- 北極海氷の初期の発展とその気候の冷却とのつながりを再構築する.
主な方法:
- 特別に豊富に存在する海氷に依存した化石ダイアトム (Synedropsis spp. ) を実施する.
- 石英粒の質感特性を調べ,IRD輸送を決定する.
- コスモポリタンダイオトムのデータと既存のIRD記録の統合.
主要な成果:
- 中期エオセンの北極海氷の有力な証拠は,シネドロプシス diatoms の高い豊富さによって示されています.
- クォーツ粒子の分析は,この期間のIRDの主な輸送体としての海氷を支持しています.
- 2段階の海氷の形成:最初のエピソード的形成は,約47.5万年前のもので,その後の季節的な沖合形成は,約0.5万年後のものです.
結論:
- この研究は,北極海氷の発展の200万年の記録を,初期の中期エオセンの間に提供している.
- 温暖で氷のない北極から季節的な冬の海氷のある北極への重要な移行を文書化しています.
- 北極海氷の発生を,中期エオセンの気候の冷却段階の開始と結びつける.
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