岩石岩から解釈されるように,米国西部のサブドクションゾーンが進化している
Science (New York, N.Y.)
|November 19, 1971
まとめ
アンデシト岩石の化学構造は,ケノゾーイク初期と中期の間,アメリカ西部の下には2つの異なる沈殿地帯があることを示している. メソゾイク期の沈殿は,単一の,より急なゾーンに沿って発生し,構造の歴史を明らかにしました.
科学分野:
- 地質学 地質学 地質学
- テクトニクス (地質学) とは
- ペトロロジー・ペトロロジーとは
背景:
- サブドクションプロセスは,大陸の縁を大きく形作る.
- 過去の潜水動態を理解することは,構造進化の解釈に極めて重要です.
- アンデシット岩は,マグマティックとテクトニック活動の重要な指標として機能します.
研究 の 目的:
- 米国西部の地下に潜伏するゾーンの幾何学とタイミングを調査する.
- 地化学のプロキシを用いてメソゾイクとケノゾイクにおける潜水現象を区別する.
主な方法:
- アンデシット岩におけるK(2) OとSiO(2) の比率の分析.
- 地化学データを解釈して,潜水地帯の特徴を推測する.
主要な成果:
- 初期・中期ケノゾイクにおけるサブダクションは,2つのサブパラレル・インブリケート・ゾーンに沿って発生し,東に向かって約20度 (20度) に沈んだ.
- 西の潜水帯は大陸の縁に位置し,東の帯は大陸板の下,より深く位置していた.
- メソゾイク期のサブダクションは,単一の,より急なサブダクションゾーンに沿って発生したと推論されています.
結論:
- アンデシット岩の地化学的変異は,独特のケノゾイクとメソゾイク潜水構造の有力な証拠を提供します.
- 特定されたサブドクションゾーンは,米国西部のプレート構造の歴史の洞察を提供します.
- この研究は,西向きに沈む潜水流のモデルと,大陸の地殻の進化への影響を洗練しています.
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