Study of thermal history of the constituent components in chondrites and the parent body process

2004-2006年的科研成果总结如下：热变质作用研究：研究了各种球粒陨石中铁镍金属和尖晶石群矿物的岩石学和矿物学特征，并对比了这些球粒陨石中硅酸盐的特征特征。我发现这些矿物质是最原始球粒陨石热变质作用的最佳指标。特别是Fe-Ni金属的织构和化学成分等特征，较好地反映了低温条件下的热过程。我提出了一个量化指标来表示Fe-Ni金属的变质程度，这与最近提出的另一个变质指标是一致的。尖晶石群矿物也反映了低品位的热变质作用。此外，我发现一些尖晶石群矿物是残余相，在球粒中没有熔化。这表明某些尖晶石群矿物保留了球粒前体阶段的信息。震荡CB球粒陨石的研究：我研究了一个CB球粒陨石，Gujba，与严重震荡的普通球粒陨石进行比较。我在这个球粒陨石上发现了一些高压多晶。特别是，我发现了coesite，这是第一次从各种陨石中发现。我提出一些碳质球粒陨石和普通球粒陨石一样经历了剧烈的撞击过程。我在陨石学会年会、国际矿物学协会年会、国家极地研究所陨石研讨会上报告了这些结果。

The scientific results of 2004-2006 are summarized as follows ;1. Study of thermal metamorphism : I studied petrological and mineralogical features of Fe-Ni metal and spinel group minerals from various kinds of chondrites, in comparison with the characteristic features of silicates in these chondrites. I found these minerals are the best indicator for the thermal metamorphism of the most primitive chondrites. Especially, the characteristic features of Fe-Ni metal, such as texture and chemical composition, well reflect the thermal process under low-temperature conditions. I proposed a quantitative indicator to show the metamorphic degree from Fe-Ni metal, which is well consistent with another metamorphic indicator proposed recently. Spinel group minerals also reflects the low-grade thermal metamorphism. In addition, I found some spinel group minerals are relic phase which did not melt in chondrules. This indicates that some spinel group minerals preserve the information in the precursor stage of chondrules.2. Study of shocked CB chondrite : I studied a CB chondrite, Gujba, in comparison with heavily shocked ordinary chondrites. I found some high-pressure polymorphs from this chondrites. Especially, I found coesite which is the first discovery from any kinds of meteorites. I proposed that some kinds of carbonaceous chondrites experienced heavy impact process, like ordinary chondrites.I reported all these results in the annual meeting of the Meteoritical society, the international mineralogical association, and the meteorite symposium in National Institute of Polar Research.