地球のマントルの高度な siderophile 要素は,月を形成する衝撃の時計として使用されます
Seth A Jacobson1, Alessandro Morbidelli2, Sean N Raymond3
11] Observatoire de la Côte d'Azur, Laboratoire Lagrange, Boulevard de l'Observatoire, BP 4229, 06304 Nice Cedex 4, France [2] Universität Bayreuth, Bayerisches Geoinstitut, 95440 Bayreuth, Germany.
Nature
|April 4, 2014
まとめ
月を形成した巨大衝突は,太陽系から4千万年後にかなり遅れて起こった.
科学分野:
- 惑星科学は惑星科学である.
- 地質化学 地質化学
- 天体物理学 天体物理学
背景:
- 月を形成した巨大な衝突は,地球の核形成とマントルの進化にとって極めて重要です.
- このイベントの年代付けは困難で,太陽系の凝縮から3000万年から1億年までの年齢が提案されています.
- 以前のモデルでは,月形成の衝撃の正確なタイミングについてコンセンサスが欠けている.
研究 の 目的:
- 月形成の巨大衝突イベントの年齢を精錬するために.
- 巨大衝突のタイミングと遅い蓄積の間の強固な関係を確立するために.
- 地化学的証拠を用いて月形成のタイミングを制限する.
主な方法:
- 地上の惑星形成シナリオ (古典的およびグランドタック) をモデル化するためにN体シミュレーションを使用しました.
- 最後の巨大衝突のタイミングと,その後の遅い蓄積量との相関を調査した.
- 地球のマントルにおける高度サイデロフィール元素 (HSE) 濃度を分析し,後期収縮質量を制限し,衝撃のタイミングを推論した.
主要な成果:
- 凝縮後の4千万年以内の月形成を99.9%の信頼レベルで排除した.
- 巨大衝突遅延と遅い蓄積量との予測可能な逆関係を示した.
- HSEの豊富さに基づいて,凝縮後の月形成年齢を95 ±3200万年と決定しました.
結論:
- 月形成の衝突は,太陽系の凝縮から4千万年後に顕著に起こった.
- 地球のマントルに大量に存在するHSEは,月形成の出来事を年代測定するための堅固な時計を提供します.
- HSE記録の潜在的な複雑さを考慮しても,同位体制約は,月形成の遅いタイミングを支持します.
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