厚い氷床で覆われた北極海の氷河期
Walter Geibert1, Jens Matthiessen2, Ingrid Stimac2
1Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany. walter.geibert@awi.de.
Nature
|February 4, 2021
まとめ
氷棚の下には2つの主要な北極の淡水区間があり 過去の海洋状態と海面記録に影響しています これは北極の氷河の歴史に関する 過去の解釈に異議を唱えます
科学分野:
- 古代海洋学
- 海洋地質学
背景:
- 初期の仮説では 北極の氷棚が 海底の浸食的な特徴によって 支持されていると示唆されていました
- 氷河期に広大な北極の氷棚があったという確固たる証拠は 海洋堆積物記録にはありませんでした
研究 の 目的:
- 広大な北極の氷棚と淡水区間の直接的な海洋沈殿物の証拠を提供するためです.
- 北極海の状況に対するこれらの出来事のタイミングと影響を調査する.
- トリウム230の記録と沈殿率の異常を説明するために
主な方法:
- アイソトープシグネチャー,特にトリウム230の海洋沈殿体核の分析.
- エミリアニア・フクセイを含む石灰岩ナノ化石の特徴
- 水流の推定と境界条件の分析
主要な成果:
- 少なくとも2つの主要な北極の淡水区間の証拠は,広範囲の氷棚の存在と一致しています.
- これらの間隔の年代付けは70,000~62,000年 BP (海洋同位体ステージ4) と150,000~131,000年 BP (海洋同位体ステージ6) です.
- トリウム-230の記録における広範な最小値の説明,年代付けの不一致を解決する.
結論:
- 北極海は氷床で覆われており 特定の氷河期には淡水で満たされていました
- 約900万立方キロメートルの新鮮な水で 既存の海面再構築に 挑戦しました
- 大量の淡水が北大西洋に放出される可能性は 短期的にはあり得ます
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