ガラパゴス・プラットホームからの海底玄武岩のマントル・プルーム・ヘリウム
Science (New York, N.Y.)
|December 24, 1993
まとめ
ガラパゴスのホットスポットは,ヘリウム-3/ヘリウム-4の比率が高く,ガスのないマントルの羽根を示しています. 空間的変異は,羽根の動態と,アステノスフィアと拡散センターとの相互作用を明らかにします.
科学分野:
- 地質化学 地質化学
- イソトープ地球化学 イソトープ地球化学
- マントルの地力学 マントルの地力学
背景:
- ガラパゴス諸島は,火山活動により,マントルの羽根を研究するための重要な場所です.
- ヘリウムイソトープ比 (ヘリウム-3/ヘリウム-4) は,マントルの源と過程の重要なトレーサーである.
研究 の 目的:
- ガラパゴス諸島の海底玄武岩ガラスのヘリウム同位体の地化学を調査するために.
- ガラパゴスマントルの羽根の性質とその周囲のマントルとの相互作用を理解するために.
主な方法:
- 海底ベースルトガラスにおけるヘリウム3/ヘリウム4比の分析.
- 群島全体の同位体変動の地球化学マッピング.
主要な成果:
- 西と南西のガラパゴス島のガラスのヘリウム-3/ヘリウム-4比は,大気比の23倍に達する.
- これらの高い比率は,ガソリンが比較的ないマントルの羽根源が,ガラパゴス熱点にあることを示唆している.
- 他の場所の低い比率は,枯渇したアステノスフィアの物質との混合を示し,空間的な変動は,羽根-アステノスフィアの相互作用を反映しています.
結論:
- ガラパゴスのホットスポットには,ハワイ,アイスランド,サモアに匹敵する,ガスのないマントルの有意な羽根が宿っている.
- ヘリウムイソトープ比の空間的変動は,羽根の動力学と,ガラパゴス広場と周囲のアステノスフィアとの相互作用の洞察を提供します.
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