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

2004-2006年的科学成果总结如下：1。热变质作用研究：研究了不同类型辉长岩中铁镍金属和尖晶石族矿物的岩石学和矿物学特征，并与这些辉长岩中硅酸盐的特征进行了对比。我发现这些矿物是最原始的花岗岩热变质作用的最佳指示剂。特别是铁镍金属的织构、化学成分等特征很好地反映了低温条件下的热过程。提出了一种反映铁镍金属变质程度的定量指标，与最近提出的另一种变质指标相一致。尖晶石族矿物也反映了低级热变质作用。此外，还发现了一些尖晶石族矿物是未熔融成球粒的残相。这表明某些尖晶石族矿物保存了球粒陨石形成前体阶段的信息.冲击CB球粒陨石的研究：我研究了CB球粒陨石，Gujba，与严重冲击的普通球粒陨石进行比较。我在这条鱼上发现了一些高压多晶型体特别是我发现了柯石英，这是第一次从任何种类的陨石中发现。我提出了某些碳质陨石与普通陨石一样经历了强烈的撞击过程，并在国际矿物学协会陨石学会年会和国家极地研究所陨石研讨会上作了报告。

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.