シェルゴッティ隕石のシオ2ポリモルフ:衝突後のシオ2ポリモルフ:衝突イベントへの影響
T G Sharp1, A El Goresy, B Wopenka
1Department of Geology, Arizona State University, Tempe, AZ 85287, USA.
Science (New York, N.Y.)
|May 29, 1999
まとめ
火星の隕石"シェルゴッティ"は,地球の下層マントルのストイスホイット後の構造に似た,密度の高いSiO2相を含んでいる. この高密度ポリモルフは,惑星体の極端な衝撃圧力の指標として機能する.
科学分野:
- 地質化学 地質化学
- ミネラロジーは,鉱物学です.
- 惑星科学は惑星科学である.
背景:
- 火星の隕石は,惑星の形成と進化についての洞察を提供します.
- シリカ (SiO2) の高圧相を理解することは,深層地球と惑星の内部モデルにとって極めて重要です.
研究 の 目的:
- 火星の隕石シェルゴッティの鉱物学的組成を調べるために.
- 異星人のサンプル内の高圧シリカポリモルフを特定するために.
- これらのポリモルフがショックイベントの指標としての可能性を評価する.
主な方法:
- 送信電子顕微鏡 (TEM) を用いて,シェルゴッティ隕石の微細構造を分析した.
- 電子 difrractionは,識別された相の結晶学的構造を決定するために使用されました.
主要な成果:
- 構造的にはアルファ-PbO2構造を持つポストステシュホイトに類似する,密度の高いオルソロンビックSiO2相がシェルゴッティで特定されました.
- この相は,高密度のシリカのポリモルフを表しています.
- ショックを受けたアコンドライトにこの多形体の存在は,極端なショック圧力が経験されたことを示唆しています.
結論:
- 火星の隕石シェルゴッティには,地球の下層マントルで予想されるものと似た高圧のシリカポリモルフが含まれています.
- ストイショビット後のSiO2構造は,衝撃を受けた隕石や惑星の内部における極端な衝撃圧力の信頼できる指標として利用できます.
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