潮トモグラフィは地球の深層マントルの浮力を制限する
Harriet C P Lau1, Jerry X Mitrovica1, James L Davis2
1Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA.
Nature
|November 17, 2017
まとめ
地球の固い地球潮は,アフリカと太平洋の下のLLSVPは,これまで考えられていたよりも密度が高いことを明らかにしています. これはマントルのダイナミクスを影響する 高密度の化学成分によって浮力性が支配されていることを示しています
科学分野:
- 地理学
- 地球科学
- 地震学
背景:
- 固体潮は,月と太陽の重力による地球の表面の移動です.
- 大型の低切断速度領域 (LLSVPs) は,コアマントルの境界にある巨大な構造物であり,その浮力性は議論されている.
- LLSVPの密度を理解することは,マントルのダイナミクスと地球の進化にとって極めて重要です.
研究 の 目的:
- LLSVPsの深層マントルの浮力を制限するために,ボディの潮変形を使用します.
- アフリカと太平洋のLLSVP内の密度異常を調査する.
主な方法:
- 半日間の身体の潮変形を分析した
- 精密な表面移動データを用いるグローバル・ポジショニング・システム (GPS) の測定.
- 密度変動を分析するために確率的アプローチを適用した.
主要な成果:
- LLSVPの下部の3分の2は,周囲のマントルより約0.5%高い平均密度を示しています.
- この密度異常はマントルの底部に 集中しているかもしれない
- LLSVPの平均浮力を約0.5%に制限しました.
結論:
- LLSVPの浮力は主に高密度の化学成分の濃縮によって引き起こされます.
- 沈殿した海洋プレートや原始物質は,これらの密度の高い構成要素の源である可能性が高い.
- LLSVPの密度構造は,マントルのコンベクション,LLSVPの安定性,および地球システムの長期的な進化に重要な意味を持っています.
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