まとめ
スフェーネ U-Pb年代測定は,古代の岩石の年代を信頼できるものとして提供し,しばしばジルコンよりもコンコンダントな結果をもたらします. この方法では,元の結晶化だけでなく,変異の出来事を年代付けることができます.
科学分野:
- ジオクロノロジー (Geochronology) について
- イソトープ地球化学 イソトープ地球化学
- ミネラロジーは,鉱物学です.
背景:
- 古代の岩石の正確な年代測定は,地球の歴史を理解するために不可欠です.
- スフェン (チタナイト) は,様々な岩のタイプで一般的なアクセサリー鉱物です.
- ウラン-鉛 (U-Pb) 年代測定は,広く使用されている地質年代測定技術です.
研究 の 目的:
- スフェネを用いたU-Pb年代測定の信頼性を評価するために.
- スフェンU-Pbの年齢のコンコンダンスと,ジルコンやバイオタイトのような共存する鉱物との比較をするために.
- 変形現象の年代測定におけるスフェネの有用性を評価する.
主な方法:
- ウラン鉛 (U-Pb) の同位体分析は,スフェンのサンプル14個で実施した.
- 年齢はPb-206/U-238とPb-207/Pb-206の比率を用いて決定した.
- スフェンの年齢は,同じ岩石サンプルから共存するジルコンとバイオタイトの年齢と比較されました.
主要な成果:
- スフェネのサンプルは一致した,またはほぼ一致したU-Pbの年齢を示し,最大10%の不一致を示した.
- スフェネは7つの比較分析で,共存するジルコンよりも一貫して高い年齢コンコンドランスを示しました.
- 2つの変形岩で,スフェネは,元の結晶化ではなく,変形のタイミングを日付付けました.
結論:
- スフェンはU-Pb地質年代学,特に古代の岩石の信頼性の高い鉱物です.
- スフェネは,多くの地質学的な環境でジルコンと比較して優れた年齢コンコンダンスを提供しています.
- スフェネU-Pb年代測定は,変形現象のタイミングを決定するのに有効です.
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