イギリス南西部のトリアス期後半の衝突噴出層
Gordon Walkden1, Julian Parker, Simon Kelley
1Department of Geology and Petroleum Geology, Kings College, University of Aberdeen, Aberdeen AB24 3UD, UK. spherules@abdn.ac.uk
Science (New York, N.Y.)
|November 16, 2002
まとめ
研究者らは,イギリスでトライアス紀の衝突噴出層を発見し,その中には球体とショックを受けたクォーツが含まれている. この発見は,メソゾーイク時代に地外生命が地球に衝突したことの重要な証拠である.
科学分野:
- 地質学 地質学 地質学
- 惑星科学は惑星科学である.
- パレオントロジー・パレオントロジー
背景:
- 陸上の衝突クレーターはよく記録されていますが,それに関連する遠端放出堆積物は,堆積物の記録では稀です.
- 衝突事故を理解するには,その噴出物層を特定し,特徴づけることが必要です.
研究 の 目的:
- イギリス南西部のトライアス紀の大規模な衝突噴出堆積物の発見を報告するために.
- 噴出物層を年代測定し,既知の衝撃構造と相関させる.
- メソゾイク期の影響と絶滅を理解するために,この発見の影響を分析する.
主な方法:
- イギリス南西部の地質学的なフィールドワークで,堆積堆積を特定し,サンプルを採取する.
- 特徴的な衝撃球体や衝撃クォーツを特定するための顕微鏡分析.
- 射出層内のカリウムフェルドスパートのアルゴン-アルゴン年代測定.
主要な成果:
- スフェルルとショッククォーツを含むトライアス紀の沈殿堆積物の特定,これは衝撃からの噴出層を示す.
- アルゴン・アルゴン年代測定により,貯蔵物の年齢は214年+/- 250万年となった.
- この年齢は,いくつかのトライアス紀の衝突クレーター,特にマニクーアガンとロシェチュアートと一致しています.
結論:
- 発見された堆積物は,メソゾーイク時代の地外衝突の希少な堆積物記録を表しています.
- この発見は,衝突イベントの頻度,効果,動態を解読するのに役立ちます.
- 更に研究することで,この噴出層と化石の絶滅のタイミングとの関係を調べることができます.
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