大規模なマントルの融解と大陸の成長の間のリンクは,オスミウムイソトープで見られる
D G Pearson1, S W Parman, G M Nowell
1Northern Centre for Isotopic and Elemental Tracing, Department of Earth Sciences, Durham University, South Road, Durham DH1 4QE, UK. d.g.pearson@durham.ac.uk
Nature
|September 14, 2007
まとめ
地球の大陸の地殻は,連続的にではなく,パルスで成長した. オスミウムイソトープを用いた新しい研究は,マントルの枯渇イベントが地殻形成のピークと一致することを明らかにし,私たちの惑星の地殻のパルス成長モデルをサポートしています.
科学分野:
- 地質化学 地質化学
- ジオクロノロジー (Geochronology) について
- 惑星科学は惑星科学である.
背景:
- 地球の大陸地殻の形成のタイミングとメカニズムは未だに議論されている.
- 地殻の年齢分布はピークを示しており,パルス成長または保存バイアスを示唆しています.
- レーニウム187/オスミウム187 (187Re-187Os) 崩壊システムは,マントルの枯渇を追跡しています.
研究 の 目的:
- マントルの枯渇イベントのタイミングを調査するために.
- マントルの分化と大陸の地殻形成を結びつけるために.
- 地殻の成長のパルス対連続モデルをテストする.
主な方法:
- オスミウム合金粒子を分析するためにレーザーアブレーションを使用しました.
- 量化オスミウムイソトープ組成は,枯渇年齢を決定する.
- 上層マントルのサンプルの枯渇年齢を統計的に分析した.
主要な成果:
- マントルの枯渇年齢は,群集され,均等に分布していません.
- 特定された枯渇年齢のピークは,およそ12億年,19億年,27億年です.
- これらのマントルの枯渇イベントは,大陸の地殻生成ピークと相関しています.
結論:
- クープレッド,グローバル,パルスマントル-地殻の差異化に関する証拠を提供する.
- 大陸の成長のモデルを,エピソード的,大規模なマントルの融解を通してサポートします.
- 地殻-マントルの進化を理解する上で187Re-187Osシステムの役割を強調しています.
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