ラウ・バックアークにおけるマントルの流れの複雑なパターン
G P Smith1, D A Wiens, K M Fischer
1Department of Earth and Planetary Sciences, Washington University in St. Louis, 1 Brookings Drive, CB1169, St. Louis, MO 63130, USA.
まとめ
シーア波分裂は,トンガの弧とラウ盆地の下の複雑なマントルの流れを明らかにします. この流れは,プレート沈下だけでなく,太平洋プレートと相互作用するサモアの羽根の影響を受けています.
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
- マントラダイナミクス マントラダイナミクス
背景:
- トンガ・アークとラウ・バック・アークのアジムタルアニソトロピーのパターンは複雑です.
- 以前のモデルでは,これらのパターンを,マントルの流れと太平洋プレートの下落を組み合わせて説明するのに苦労しました.
研究 の 目的:
- トンガ・アークとラウ・バック・アークにおける複雑なアジムタルアニソトロピーを調査するために.
- この地域のマントルの流れの背後にある原動力を理解するために.
主な方法:
- 地元の地震から発生したシェア波の分裂の分析.
- 陸地と海底の両方で地震データを記録する.
- ヘリウム同位体データとの相関.
主要な成果:
- プレート結合マントルの流れで説明できない複雑なアジムタルアニソトロピーを観測した.
- マントルの流れ方向の回転を特定した:収束-平行 (フィジー),北-南 (ラウ盆地),および弧-平行 (トンガ弧).
- ヘリウムイソトープは,太平洋プレートの裂け目を通ってサモアの羽根がラウ盆地に流れることを示しています.
結論:
- トンガ・アークとラウ・バック・アークの下のマントルの流れは複雑で,単純なプレート沈下を超えた要因の影響を受けます.
- サモアの羽根は,ラウ盆地におけるマントルの動態を形作る上で重要な役割を果たしています.
- 太平洋プレートの裂け目が,サモア・プルームとプレートとの相互作用を容易にする.
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