パレオセノ・エオセノ熱最大期における海洋の急速な酸化
James C Zachos1, Ursula Röhl, Stephen A Schellenberg
1Earth Sciences Department, Earth and Marine Sciences Building, University of California, Santa Cruz, Santa Cruz, CA 95064, USA. jzachos@emerald.uscs.edu
まとめ
パレオセーヌ・エオセーヌ熱マキシマム (PETM) は,深海の炭酸塩の急速な溶解を引き起こし,大規模な炭素の放出を示唆しました. この出来事は,カルシット補償深さ (CCD) を100,000年以上にわたって劇的に低下させた.
科学分野:
- パレオセアノグラフィー
- 地質化学 地質化学
- 気候科学 気候科学
背景:
- パレオセーヌ・エオセーヌ熱極限 (PETM) は,大規模な炭素放出に関連しており,海洋のpHを下げ,カルシート補償深さ (CCD) を押し上げると理論化されています.
- 海洋化学と炭酸塩溶解に対するPETMの影響を理解することは,過去の気候現象を再構築するために不可欠です.
研究 の 目的:
- 新しい深海コアデータを用いて,PETM中に炭酸塩溶解のタイミングと範囲を調査する.
- この重要な地質的な出来事の際に排出される炭素と海洋学的な反応の推定を精査する.
主な方法:
- 南大西洋の5つの新しい深海沈殿部からの地化学データの分析.
- 顕著な粘土層を含む堆積層を調査し,水深の変化と炭酸塩溶解を推論する.
主要な成果:
- 地化学的なデータは,PETMの間にCCDが2km以上急激に (<10,000年) 収縮したことを示しています.
- 証拠によると,海底の大規模な炭酸塩溶解は,PETMと一致して起こったことを示唆しています.
- CCDは10万年以上にわたって徐々に回復したことを示した.
結論:
- PETMは,以前に推定されたよりもはるかに大きな炭素の放出に関連していた (>2000 x 10 ^ 9 メートリックトン).
- この炭素の急速な海洋吸収は,かなりの長時間持続する炭酸塩溶解につながった.
- シリケートの気象フィードバックは,この放出された炭素を永久に封じ込めることに役割を果たしました.
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