終点IIの海面変化のタイミングを直接決定する
Christina D Gallup1, H Cheng, F W Taylor
1Department of Geological Sciences, University of Minnesota Duluth, Duluth, MN 55812, USA. cgallup@d.umn.edu
まとめ
珊瑚年代測定により,海面が13万6000年前に大幅に上昇し,氷河周期に関するミランコヴィッチ理論の予測に異議を唱えたことが明らかになった. この発見は,過去の海面の変化と気候の動態に関する新しい洞察を提供します.
科学分野:
- 海洋地質学 海洋地質学
- 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
- 四次科学とは四次科学である.
背景:
- バーバドスのサンゴの化石は,過去の海面についての洞察を提供します.
- 最後の氷河間期と最後の前期の脱氷 (Termination II) は,主要な研究分野である.
- 氷河周期と海面変動の理解は,気候モデリングに不可欠です.
研究 の 目的:
- バルバドスのサンゴを正確に年代付けして,第2終末期における海面を再構築する.
- 再構築された海面をミランコビッチ理論の予測と比較する.
- 過去の氷河期における深海の温度を調査するために.
主な方法:
- 230Thと231Paを組み合わせた化石サンゴの放射線年代測定.
- 珊瑚の骨格における酸素同位体比 (デルタ18O) の分析.
- 既存の深海の堆積物コアの記録 (V19-30/V19-28) と比較した.
主要な成果:
- 135.8 +/- 0.8万年前のサンゴは,海面が現在のより18 +/- 3メートル低いことを示しています.
- 海水位は,13万6000年前に最後の氷河期間の水準のピークの20%以内に上昇しました.
- 酸素同位体サブステージ6e (168,000年前) のサンゴは,現在の海面より38+/- 5メートル下の海面を示しています.
結論:
- 13万6000年前の海面上昇は,ミランコビッチ理論の予測と矛盾しています.
- 軌道強制と静止調整は,脱氷に影響を及ぼした可能性がある.
- 珊瑚のデータは,氷河期間の低温の深海の温度を確認し,この結論を前の氷河周期に拡張します.
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