地上植物の生態系が白亜紀と三紀の境界,西部の内陸で破壊された
Science (New York, N.Y.)
|September 7, 1984
まとめ
北米の白亜紀と三次紀の境界線は,異なったイリジウムに富んだ粘土層を示しています. この層は,突然の生態系シフトをマークし,大陸規模の壊滅的な出来事を示しています.
科学分野:
- パレオントロジー・パレオントロジー
- 地質学 地質学 地質学
- エコロジー エコロジー エコロジー
背景:
- クレタセウス-第3期 (K-Pg) の境界は,地球の歴史における重要な移行をマークします.
- この境界は,しばしば地質学的なマーカーや化石記録によって識別される.
- 以前の研究では,様々な地域におけるK-Pg境界イベントを調査した.
研究 の 目的:
- 北米西部の白時代と三次期の境界のパリノロジカルな特徴を定義する.
- K-Pg境界でのイベントの生態学的影響を調査する.
- 化石の証拠に基づいて,破壊の規模と性質を推論する.
主な方法:
- 北米西部内部の堆積物核のパリノロジック分析.
- 境界層を越えた花粉と胞子集合体の識別と定量化.
- イリジウムに富んだ粘土層の地化学分析.
主要な成果:
- クレータ紀と三次紀の境界は,イリジウムに富んだ粘土層の頂点に正確に位置しています.
- 特定の花粉種の突然の消失が観察されました.
- 境界事象の直後に,胞とアニオ精子の花粉の比率の急速で顕著な変化が起こりました.
結論:
- 観測された古生物学的な変化は,陸上の生態系が大陸全体で破壊されていることを示しています.
- 地質学的に短いが顕著な生態学的シフトは,大規模な壊滅的な出来事を示唆しています.
- これらの発見は,白亜期の終わりに大規模な衝撃またはイベントがあったという仮説を裏付けている.
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