ハダイアからパレオアルカイアまで,ジルコンの磁気によって明らかにされた静止層構造
John A Tarduno1,2,3,4, Rory D Cottrell5, Richard K Bono6,7
1Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY, USA. john.tarduno@rochester.edu.
Nature
|June 14, 2023
まとめ
初期の地球はプレート構造ではなく 静止層構造だったのかもしれません これは,エオルカイア時代にプレート構造による地化学的サイクルなしに生命が存続できたことを示唆している.
科学分野:
- 地理科学
- 古磁気学
- 初期の地球研究
背景:
- プレート構造の発生は 地球の永続的な居住能力にとって 決定的ですが まだ不確実です
- プレート構造と静止層構造を区別することは,古代の岩石の変化のために困難です.
研究 の 目的:
- 初期の地球の構造を研究する
- プレート構造の始まりのタイミングを 判断するために
主な方法:
- 主要な磁石を含むデトリタルジルコンの古強度データ解析.
- バーバートン・グリーンストーン・ベルトのデータと ジャック・ヒルズのデータを比較した.
主要な成果:
- エオアルカイアからメソアルカイアまでのパレオインテンシティパターンは,ジャック・ヒルズのものと類似しており,ジルコンの記録の正確性を確認しています.
- 39億から34億年前の ほぼ恒常的なパレオフィールド値は,不変の緯度を示しています.
- このパターンは,現代のプレート構造ではなく, 停滞した蓋のコンベクションの予測と一致しています.
結論:
- 初期の地球 (3.93.4 Ga) はおそらく静止状態だった.
- プレートテクトニクスによる循環なしの 静止層の環境で 生命が誕生し 存続したのかもしれません
- この発見は 初期の生命の居住可能性のために プレート構造の必要性を 疑問視しています
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