メソシデライトクラストは,太陽系の岩石の中で最も極端な陽性ユーロピウム異常を持つ
Science (New York, N.Y.)
|August 21, 1992
まとめ
メソシダライトで見つかったピゴニットプラジオクラゼガブロは,重要なユーロピウム異常を含む極度の希土元素 (REE) 分割を示しています. これらの発見は,太陽系初期の小惑星で複雑で多段階の火性のプロセスが起こったことを示唆しています.
科学分野:
- * 惑星科学 (惑星科学)
- *地化学について
- * ペトロロジー・ペトロロジー
背景:
- * メソシデライトは,岩性岩のクラストを含んだ,ブレッチ状の石と鉄の隕石です.
- * メソシデライト内のピゴニット・プラジオクラゼ・ガブロは,珍しい地化学的サインを示しています.
- * 稀土元素 (REE) の分割パターンは,岩火および変形過程の洞察を提供します.
研究 の 目的:
- * メソシデライトから採取したポピオニット・プラジオクラゼ・ガブロクラストの極度の稀土元素 (REE) 分割を分析する.
- *これらのクラスト内のメリリットのREEパターンを調査し,シリケート均衡との関係を調べる.
- * 小惑星の親体における初期の火性および変形過程を推論する.
主な方法:
- *ガブロイク・クラストとメリリットの稀土元素 (REE) 濃度に関する地化学分析.
- *観測されたREEパターンを,地球,月,その他の隕石の親体からの既知の岩石と変形岩石との比較.
- *初期太陽系プロセスの文脈におけるREEデータの解釈.
主要な成果:
- *ガブロクラストは,以前知られている岩石よりも大きな正のユーロピウム異常を持つ極端なREE分断を示しています.
- *軽量のREEは重量のREEと比較して著しく枯渇し,比較可能な累積ガブロの枯渇を上回ります.
- *クラスト内のメリリットは,光のREEの枯渇と,変形均衡による大きな陽性ユーロピウム異常を示している.
結論:
- * メソシデライトクラストの極端なREE比率は,太陽系初期の小惑星の多段階の火性の過程を示しています.
- * 衝突や太陽誘導によって引き起こされる可能性のある大規模な地殻の融解が,これらのプロセスを駆動した可能性が高い.
- *これらの発見は,初期の小惑星の進化と地殻形成に関する既存のモデルに異議を唱える.
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