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熱ハリン循環の危機と,プレイストセーン中期の移行期における影響
Leopoldo D Pena1, Steven L Goldstein2
1Lamont-Doherty Earth Observatory of Columbia University, 61 Route 9W, Palisades, NY 10964, USA. leopoldo@ldeo.columbia.edu.
まとめ
プレイストセーン中期の移行 (MPT) は,海洋熱ハリン循環 (THC) を混乱させ,それを著しく弱めた. この循環の危機は,氷床の成長を促進し,10万年の氷河周期を安定させました.
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
- 海洋学 海洋学とは
- 地質化学 地質化学
背景:
- プレイストセンの中期移行 (MPT) は,氷河期と氷河期間のサイクルを ~41kyr から ~100kyr 期にシフトさせた.
- このシフトは,ミランコビッチ・フォースリングに大きな変化なしに発生し,他の地球系フィードバックが関与していることを示唆しています.
研究 の 目的:
- MPT中の海洋熱ハリン循環 (THC) の役割を調査する.
- 100kyrサイクルの出現に関連したTHCの変化を特定する.
主な方法:
- 海の堆積物におけるネオジミウム (Nd) の同位体の分析.
- 過去の海洋循環パターンの再構築.
主要な成果:
- MPT中に,特に海洋同位体段階 (MISs) 25と21 (~950860 ka) の間に,THCの主要な破壊と弱化が発生しました.
- 氷河期間のMIS 23 (~900 ka) 期間中にTHCの例外的な弱まりが観察されました.
- MPT後のTHCの回復は,氷河期間の持続的な弱さによって特徴付けられました.
結論:
- 弱まったTHCによって特徴づけられたMPT海洋循環危機は,100kyrサイクルへの移行の重要な要因でした.
- この危機は,大気中のCO2の吸収と高緯度の氷床の成長を促進し,より長いサイクルを安定させました.
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