エレメンタル異常は白紀-三次紀の境界,ウッドサイド・クリーク,ニュージーランド
Science (New York, N.Y.)
|November 2, 1984
まとめ
ニュージーランドのウッズサイド・クリークにある白紀と三次紀の境界のシェールには,高濃度のイリジウムとシデロフィール元素がある. これらの発見は,境界物質の源泉として地球外生命体の衝突イベントを裏付けている.
科学分野:
- 地質化学 地質化学
- パレオントロジー・パレオントロジー
- 宇宙化学 (コスモケミストリー)
背景:
- クレータ紀-三次紀 (K-T) の境界線は,重大な大量絶滅の出来事を示しています.
- イリジウム異常は,地球外生命体の衝突の重要な指標である.
- 以前の研究では,世界中でK-T境界部位でイリジウムの異常を特定しました.
研究 の 目的:
- ニュージーランドのウッズサイド・クリークにあるK-T境界シェイルの元素組成を分析するために.
- 地化学データを他のK-T境界部と比較する.
- K-T境界イベントの地球外衝突仮説を評価するために.
主な方法:
- イリジウムや他のシデロフィール元素を含む27の元素を,シェールサンプルで測定する.
- K-T境界の8ミリメートルのシェール分離のストラティグラフィック分析.
- 炭酸塩フリーベースでの元素濃度の比較.
主要な成果:
- イリジウム,金,銅,コバルト,クロム,ニッケル,ヒ素,モリブデン,鉄の濃縮は,シェイルの基底2mmに発生する.
- ニュージーランドのシェールとデンマークのシェールとの間に,驚くべき構成の類似性がある.
- 基礎層における異常に高いイリジウム濃度 (153 ng/g) と統合値 (187 ng/cm2) は,他の海洋境界シェールよりも高い.
結論:
- 元素の濃縮,特にイリジウムとシデロフィール元素は,Woodside CreekのK-T境界物質の地球外的な源を強く支持しています.
- イリジウム/黄金の比率は,地球外の起源と一致しています.
- この発見は,地球の歴史における地球外生命体の影響のグローバルな重要性を強化している.
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