北米プレートにおけるコンベクションによる移動の地震的証拠
David W Eaton1, Andrew Frederiksen
1Department of Earth Sciences, University of Western Ontario, London, Ontario N6A 5B7, Canada. deaton@uwo.ca
Nature
|March 23, 2007
まとめ
プレートテクトニクスの原動力は,基礎牽引の不確実性のために議論され続けている. グレート・メテオールのホットスポット・トラックの新しい分析は,西向きのプレート・ベース・シフトを明らかにし,アステノスフィアの流れがプレート・モーションを駆動することを示唆している.
科学分野:
- 地質物理学 地質物理学とは地質物理学です.
- テキトノフィジックスの物理学です.
- プレート・テクトニクス (プレート・テクトニクス)
背景:
- プレートテクトニクスの推進力は議論されており,基礎牽引の不確実性が進歩を妨げています.
- ホットスポットトラックは,過去のプレート運動とマントルの結合に関する洞察を提供します.
研究 の 目的:
- 北米板の表面と底の間の相対運動を調査する.
- ホットスポットトラックのデータを用いて,プレート運動に対する基礎牽引効果を定量化するために.
主な方法:
- 北米東部のグレート・メテオール・ホットスポット・トラックの表面表現 (115-140 Myr) の分析.
- 表面軌道の位置をプレート再構築モデルと比較し,200 kmの深さでマントルの構造を推測するための地震トモグラフィー.
主要な成果:
- ホットスポットトラックの表面位置と推測された深さの位置との間に重大な不整合が確認されました.
- この不整列は年齢とともに増加し,プレート基の表面に対する西向きの移動を3.8 +/- 1.8 mm yr{-1}で示しています.
- 相対的な移位は,地震速度の軸とマントルの流れと一致し,アステノスフィアの流れが石層のキールに影響することを示唆しています.
結論:
- 表面と下側の相対プレート運動の直接的な推定は,年齢制限のピアシングポイントを使用して可能です.
- アステノスフィアの流れは,北米のプレート運動の重要な原動力として作用し,石層の基板を変形させるように見える.
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