オスミウムイソトープの異質性は,海中の玄武岩の構成段階にある
Abdelmouhcine Gannoun1, Kevin W Burton, Louise E Thomas
1Department of Earth Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, UK. a.gannoun@open.ac.uk
まとめ
中洋のベースタルト (MORB) の放射性同位体変動は,マントルの源の違いを反映している. MORB鉱物からのレニウム・オスミウム (Re-Os) 同位体データは,結晶化年齢とマントルの源の特徴を明らかにすることができます.
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
- ペトロロジー・ペトロロジーとは
背景:
- 中洋のの玄武岩 (MORB) は,放射性同位体変異を示し,しばしば地球の上層マントルの組成と関連しています.
- MORBにおけるレニウム・オスミウム (Re-Os) 同位体系は,構成相における高いRe/Os比によって特徴付けられています.
- これにより,187Reの腐敗から放射性187Osの急速な生成が起こります.
研究 の 目的:
- MORB源を理解する上でRe-Osイソトープ体系学の有用性を調査する.
- MORB鉱物データからマントルのソース特性を決定する可能性を調査する.
- 正確な年齢制約と初期オスの同位体値を取得するための方法を確立する.
主な方法:
- MORB.を構成する鉱物におけるRe-Os同位体の分析.
- Re-Osシステムを用いた放射線年代測定.
- マントルの源の組成と進化を推論するために,同位体データを解釈する.
主要な成果:
- MORB鉱物からのRe-Osイソトープデータは,信頼できる結晶年齢を提供することができます.
- これらのデータはまた,鉱物の均衡とオスの同位体交換の詳細を明らかにします.
- 鉱物データから得られた初期オスの同位体値は,マントルの源特性と直接相関しています.
結論:
- MORB鉱物のRe-Osイソトープ解析は,マントルの異質性を解読する上で極めて重要です.
- Re-Osシステムは,MORBの石油生成とマントルの進化を抑制するための強力なツールを提供します.
- Re-Osイソトープからの正確な年齢制約は,MORBソースシグネチャの明確な解釈のために不可欠です.
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