プレイストセンの北極海の氷棚は,氷河による深海床形から推測される
L Polyak1, M H Edwards, B J Coakley
1Byrd Polar Research Center, Ohio State University, Columbus, Ohio 43210, USA. polyak.l@osu.edu
Nature
|March 22, 2001
まとめ
プレイストセンの氷河期は,単に海氷ではなく,北極海の上に厚い氷棚を形成した可能性がある. 地質物理学的な地図作成により,氷河の広範囲な洗浄と海底の特徴が明らかになり,この棚氷の仮説を裏付けている.
科学分野:
- 地質学 地質学 地質学
- 海洋学 海洋学 海洋学
- 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
背景:
- 支配的な見解: プレイストセンの氷河期に海氷と氷山で覆われた北極海.
- 対照的仮説:北極海を覆った厚い氷河 (≥1km).
- 氷河の歴史を再現するには,詳細な海底の地図作成が必要で,これは北極に限られている.
研究 の 目的:
- 北極海におけるプレイストセンの氷床の存在と範囲を調査する.
- 恒久的な海氷の覆いと厚い氷の覆いとの議論を解決するために.
- 北極海の海底における氷河活動の証拠を探すために,地質学的データを分析する.
主な方法:
- 1999年の潜水艦SCICEXの遠征で地球物理地図システムを使用した.
- 1kmまでの深さからバックスケーター画像とサブボトムプロファイラーの記録を分析しました.
- 北極海の海底の大部分をマッピングした.
主要な成果:
- 氷河の洗浄と成形を示す複数の海底床形が特定されました.
- 海底の頂部の大規模な侵食が観察されました.
- 明確な氷河形成の特徴は,過去の氷床活動を示す証拠を提供します.
結論:
- 巨大な南極型の氷棚は,厚さ1キロメートル,長さ数百キロメートルまであり,プレイストセンの氷河期中に北極海に存在していました.
- これらの発見は,北極海の氷河覆いに関する伝統的な見解に異議を唱える.
- 海底のジオモルフォロジーは,極海における過去の氷河動態の重要な指標である.
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