核-マントルの境界にある折りたたまれた,沈殿した石層の地震検出
Alexander R Hutko1, Thorne Lay, Edward J Garnero
1Earth Sciences Department, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA. ahutko@pmc.ucsc.edu
Nature
|May 20, 2006
まとめ
沈殿する海洋板は,地球の下層マントルに到達し,D'の地震不連続性のステップを作成します. このステップは,折りたたまれたスラブ材料が,コア-マントルの境界付近のペロブスキート後の相境界を変更することによって説明されます.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- 地震学 地震学とは
- ミネラル物理学 ミネラル物理学
背景:
- 下降する海洋板は,地球の下層マントルに浸透し,D'領域に到達します.
- D'領域は,高い地震速度と不連続性を表しており,マグネシウムシリケートペロブスキート相変化と関連している可能性がある.
- 最下層のマントルの沈下したスラブの最終的な運命と地震表現は,議論の余地があります.
研究 の 目的:
- ココスプレートの下のD'領域をイメージするために.
- 地震速度の構造とコア-マントルの境界における不連続性を調査する.
- D'領域の地震特性に対する沈殿板の影響を理解するために.
主な方法:
- 横方向に偏移した切断波のキルホフ移動.
- 地震トモグラフィーでマントルの構造を推測する.
- 地震速度の不連続性の分析. 地震速度の不連続性の分析.
主要な成果:
- ココス板の下にあるD'シーア速度不連続で100kmの垂直ステップが観測されました.
- このステップは100km未満で横方向に発生しました.
- 局所的な低速度がスラブ材料の縁で検出されました.
結論:
- 観測されたステップは,コア-マントルの境界で冷たい沈殿板の折り畳みと積み重ねに起因する.
- このスラブ折り畳みにより,ペロブスキート後の段階境界が上昇し,その理由は,側面の気温が著しく低下したためです.
- 局所的な低速度は,スラブ誘発の上流が熱境界層を移動することを示唆しています.
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