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ハワイのホットスポットでクレタセア紀後半の羽根山脈相互作用の同位体証拠
1College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis 97331, USA. rkeller@oce.orst.edu
Nature
|June 23, 2000
まとめ
ハワイのホットスポットは,8100万年前に,海中の玄武岩と区別がつかないような火山活動を生み出した. これは,ホットスポットが広がる山脊と相互作用し,枯渇したマントル物質を巻き込んでいることを示しています.
科学分野:
- 地質化学 地質化学
- 地質学 地質学 地質学
- プレート・テクトニクス (プレート・テクトニクス)
背景:
- マントルの羽根と中洋の山脊は,互いに影響しあっている.
- 相互作用は,浅いバチメトリー,過度の火山活動,山脊のベースアルト組成の変化を引き起こす可能性があります.
- ホットスポット火山は,山頂に向かって引き寄せられ,化学的に変化させることができます.
研究 の 目的:
- ハワイの初期のホットスポット火山のイソトープ組成を調べるために.
- ハワイのホットスポットが,その初期の歴史において,中海の山脊と相互作用したかどうかを判断するために.
主な方法:
- デトロイトの海山から採取した火山標本のSR-Nd-Pb同位体分析.
- 同位体シグネチャーの比較は,海中の玄武岩と,ハワイのホットスポットラバとして知られている.
- プレート再構築データとの統合.
主要な成果:
- デトロイト海底山 (81 Myr ago) の火山活動は,中海のの玄武岩と同一の同位体シグネチャーを示しました.
- この同位体シグネチャーは,ハワイのホットスポット・トラックに特有のものです.
- この発見は,ホットスポットが中海の山脊の近くにあるという仮説を裏付けている.
結論:
- ハワイのホットスポットは,約8000万年前,大洋の真ん中の山脊と相互作用した.
- 羽根は,広がる中心部付近の枯渇した上層マントルの物質を運び込み,元の化学的サインを覆い隠した.
- この相互作用は,ホットスポットが進化の初期に広がる山脊に近接することで,著しく変化することが可能であることを示している.
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