実験的な水熱条件下におけるメタミクットジルコンのウランと鉛の同位体の安定性
まとめ
この研究は,高温と高圧がジルコンから有意な鉛の損失を引き起こし,ジオクロノロジーのエピソード性鉛の損失モデルをサポートすることを示しています. これはウランと鉛の年代測定の精度に影響します.
科学分野:
- 地質化学 地質化学
- 同位体地質学とは,同位体地質学である.
- メタモルフ Petrology メタモルフペトロロジー
背景:
- ジルコンのウラン-鉛 (U-Pb) 同位体系は地質年代学にとって極めて重要です.
- 鉛の喪失メカニズムの理解は,正確な放射線年代測定に不可欠です.
- メタミクットジルコンは,変化や同位体の乱れに敏感です.
研究 の 目的:
- メタミクットジルコンのウラン-鉛同位体システムの乱れを調査する.
- 特定の実験条件下で鉛の損失を定量化するために.
- ジオクロノロジカル解釈への影響を評価する.
主な方法:
- メタミクット・セイロン・ジルコンの実験的改変.
- 500°Cと1000バーの液圧で2モールNaCl溶液で処理する.
- ウランと鉛の同位体比を分析し,鉛の損失を決定する.
主要な成果:
- ウランと鉛の同位体系に重大な乱れが生じました.
- 13日以内に放射性鉛の61%の損失が観察されました.
- 実験条件では,ジルコンの同位体の完全性に大きな影響があることが示されました.
結論:
- 実験結果は,連続モデルよりもエピソード的リード損失モデルを支持しています.
- この発見は,天然ジルコンのU-Pbシステムの解釈に重大な意味を持ちます.
- 正確な地質年代測定は,そのような乱れイベントを考慮することを要求します.
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