Department of Natural Resources Management and Agricultural Engineering, Agricultural Univ. of Athens, Iera Odos 75, 11855, Athens, Greece.
California Institute of Technology, Division of Geological and Planetary Sciences, Pasadena, California, 91125, USA.
Sci Rep. 2018 Jun 29;8(1):9851. doi: 10.1038/s41598-018-28191-6.
We report the first discoveries of high-pressure minerals in the historical L6 chondrite fall Château-Renard, based on co-located Raman spectroscopy, scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy and electron backscatter diffraction, electron microprobe analysis, and transmission electron microscopy (TEM) with selected-area electron diffraction. A single polished section contains a network of melt veins from ~40 to ~200 μm wide, with no cross-cutting features requiring multiple vein generations. We find high-pressure minerals in veins greater than ~50 μm wide, including assemblages of ringwoodite + wadsleyite, ringwoodite + wadsleyite + majorite-pyrope, and ahrensite + wadsleyite. In association with ahrensite + wadsleyite at both SEM and TEM scale, we find a sodic pyroxene whose Raman spectrum is indistinguishable from that of jadeite but whose composition and structure are those of omphacite. We discuss constraints on the impact record of this meteorite and the L-chondrites in general.
我们首次在历史上 L6 球粒陨石降落的 Château-Renard 陨石中发现了高压矿物，这是基于共定位拉曼光谱、扫描电子显微镜（SEM）结合能量色散 X 射线光谱和背散射衍射、电子探针分析和透射电子显微镜（TEM）结合选区电子衍射得出的结果。单个抛光截面包含一个从40 到200μm宽的熔融脉网，没有需要多次脉代的交叉特征。我们在大于~50μm宽的脉中发现了高压矿物，包括尖晶石+蓝方石、尖晶石+蓝方石+镁铝榴石和钙钛矿+蓝方石的组合。在 SEM 和 TEM 尺度上与钙钛矿+蓝方石共存的，是一种钠质辉石，其拉曼光谱与硬玉无法区分，但组成和结构是绿辉石的。我们讨论了对该陨石和一般 L 球粒陨石撞击记录的限制。
