ネオジム-142は,ハデアンのマフィス層の証拠である
Jonathan O'Neil1, Richard W Carlson, Don Francis
1Earth and Planetary Sciences Department, McGill University, 3450 University Street, Montreal, Quebec, H3A 2A7, Canada. oneil_jo@eps.mcgill.ca
まとめ
研究者らはカナダで,独特のネオジミウム同位体シグネチャーを持つ古代の岩を発見した. これらの発見は,地球が形成された直後に形成された岩石を示唆しており,惑星の最も古い地殻を潜在的に表しています.
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.
- 初期の地球研究 初期の地球研究
背景:
- ネオジム-142 (142Nd) の同位体異常は,初期の惑星の分化に関する洞察を提供します.
- カナダのケベック州にあるヌヴワギットゥク緑石帯は,古代の地殻岩を研究するための重要な場所です.
研究 の 目的:
- Nuvvuagittuqグリーンストーンベルトの岩石の同位体組成を調べるために.
- 潜在的に古代の地殻物質の年齢と起源を決定する.
主な方法:
- 岩石サンプルにおけるネオジミウム (Nd) とサマリウム (Sm) の同位体比 (142Nd/144NdとSm/Nd) の分析.
- 146Sm-142Ndイソクロン法を用いた放射線年代測定.
主要な成果:
- ヌヴワギットゥークの岩石の中には,地上の標準よりも低い142Nd/144Nd比率 (epsilon142Nd = -0.07から -0.15) を表しているものもあります.
- 142Nd/144NdとSm/Nd比の間の正の相関は,マフィックアンフィボライト単位内で観察されました.
- この単位で,4,280 ± 5300万年の 146Sm-142Nd イソクロン年齢が決定されました.
結論:
- 分析された岩石は,地球の歴史の初期に形成された不適合な元素に富んだ物質を表しています.
- これらの発見は,Nuvvuagittuqグリーンストーンベルトが,地球上で最も古い地殻のセクションを保存している可能性があることを示唆しています.
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