Transmission electron microscopic study of the fine-grained vein matrix in the Suizhou L6 meteorite

作     者：Xie Xiande Wang Jianbo Gu Xiangping Xiong Yi Jia Shuangfeng 

作者机构：Key Laboratory of Mineralogy and Metallogeny Guangzhou Institute of Geochemistry Chinese Academy of SciencesGuangzhou 510640 China Center for Electron Microscopy Wuhan UniversityWuhan 430072 China School of Geosciences and Info-Physics Central South University Changsha 410083 Hunan China Guangdong Provincial Key Laboratory of Mineral Physics and Materials Guangzhou 510640 China 

出 版 物：《Acta Geochimica》 (地球化学学报（英文）)

年 卷 期：2016年第35卷第2期

页      面：105-110页

核心收录：

学科分类：0709[理学-地质学] 0819[工学-矿业工程] 070901[理学-矿物学、岩石学、矿床学] 07[理学] 0708[理学-地球物理学] 070401[理学-天体物理] 0704[理学-天文学] 

基　　金：financially supported by National Natural Science foundation of China under Grant 41172046 and 40972044 in part 

主　　题：Suizhou meteorite Shock vein matrix. High-pressure minerals Transmission electron microscopy 

摘      要：The mineralogy of shock vein matrix in the Suizhou meteorite has been investigated by optical and transmission electron microscopy. It was revealed that the vein matrix is composed of majorite-pyrope garnet, mag- aesiowtistite, and ringwoodite, with FeNi-FeS inter- growths. The observation and character of ring-like selected electron diffraction （SAED） patterns indicate that Lhe idiomorphic garnet crystals in the vein matrix have different orientations. The polycrystalline nature of magnesiowtistite is also confirmed by a ring-like SAED pattern. Both garnet and magnesiowtistite crystals showed sharp Jiffraction spots, signifying the good crystallinity of these ：wo minerals. The SAED pattern of cryptocrystalline 5ngwoodite shows only diffuse concentric diffraction tings. FeNi metal and troilite （FeS）, which were molten during the shock event, occur in the matrix as fine eutectic FeNi-FeS intergrowths filling the interstices between garaet and magnesiowiistite grains. Based on the phase dia- gram of the Allende chondrite and the results of this TEM study, it is inferred that majorite-pyrope garnet first crystallized from the Suizhou chondritic melt at 22-26 GPa, Followed by crystallization of magnesiowtistite at 20-24 GPa, and then ringwoodite at 18-20 GPa. The eutectic intergrowths of FeNi-metal and troilite are proposed to have crystallized during meteorite cooling and solidified at the last stage of vein formation.