ハーデアンのマフィック地殻からアルケアンのクレートンを形成する
Jonathan O'Neil1, Richard W Carlson2
1Department of Earth and Environmental Sciences, University of Ottawa, Ottawa, Canada. jonathan.oneil@uottawa.ca.
まとめ
古代カナダの岩は 初期の地球過程を明らかにしています ハドソン湾のネオアルケアンのフェルシックの地殻は,古いマフィックの地殻から形成され,初期の地殻の生存に関する以前の考え方に異議を唱えた.
科学分野:
- 地化学
- 初期の地球地質学
- 同位体地質学
背景:
- 地球の表面のプロセスは 惑星の最初の地殻の証拠のほとんどを消し去りました
- カナダ北東部のハドソン湾地層には,ネオアルケアンのフェルシックの地殻が含まれており,北東上部省の一部である.
- 初期の地殻形成を理解することは 地球の歴史を解読する鍵です
研究 の 目的:
- ネオアルケアのハドソン湾の起源と進化を調査する
- この地域における 古代の地殻の年齢と起源を 特定するためです
- 同位体データを用いて初期の地殻のプロセスを再構築する.
主な方法:
- ネオジム-142 (142Nd) とネオジム-143 (143Nd) の同位体の分析
- サマリウム-146 (146Sm) とサマリウム-147 (147Sm) の同位体データを利用する.
- 27億年前の岩石の地理年代測定
主要な成果:
- ハドソン湾の岩石 (約27億年) は142Ndで最も若い変化を示している.
- 結合された Sm-Nd 同位体データは,このアルカインの地殻が,42億年以上前の地殻の再加工によって形成されたことを示しています.
- この改造は地球の歴史の初期に 15億年の間に行われました
結論:
- 初期の地球のマフィア層は 10億年以上生き延びた
- この古代マフィア層は,アルケアの地殻の発生に重要な源岩として機能した.
- この発見は地球最古の地殻の形成と進化について 新たな洞察を与えてくれます
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