まとめ
中大西洋山脊の岩石の同位体分析は,鉛とストロンチウムの多様性を明らかにしています. 放射性同位体におけるこれらの差異は,地球における地域の化学的異質性を示唆している.
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.
- ペトロロジー・ペトロロジーとは
背景:
- 中大西洋のは,マントルの過程を理解するための重要な領域です.
- 鉛やストロンチウムなどの元素の同位体組成は,マントルの源の変化を追跡することができます.
- 以前の研究は,海洋マントルの源泉の異質性を示していた.
研究 の 目的:
- 鉛とストロンチウムの同位体組成を,中央大西洋の2つのリッジ島から採取した岩石サンプルで測定した.
- 放射性同位体の島間および島内での変動を調査する.
- 上層マントルの異質性を理解するためのこれらの変動の影響を評価する.
主な方法:
- 岩石サンプルにおける鉛とストロンチウムの同位体組成の決定.
- 鉛206/鉛204 (Pb-206/Pb-204) と鉛208/鉛204 (Pb-208/Pb-204) の比率を分析する.
- ストロンチウムイソトープ比の分析.
主要な成果:
- 鉛とストロンチウムの放射性同位体の島間および島内での有意な変動が観察されました.
- アセンション島の玄武岩は,ゴフ島 (18.4) と比較して,Pb-206/Pb-204比率 (19.5) が高かった.
- 両島のトラキトは,それぞれの玄武岩よりも放射性鉛とストロンチウムを多く示した.
結論:
- 島間の同位体組成の違いは,上層マントルのウラン・鉛・ルビジアム・ストロンチウム比の地域的変動を示唆している.
- 同位体組成は,地球のマントルの内部の化学的異質性を調査するための貴重なツールとして機能します.
- この発見は,ミッド・アトランティック・リッジの下にあるマントルの源泉の複雑な性質を強調している.
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