study on the environmental and material evolution in the early system solar based on the chemical of composition of meteorites

今年是这个项目的最后一年。在这一年中，我们进行了以下研究课题；(1)建立固体硅酸盐材料中四种卤素的分析技术及其在陨石样品中的应用；(2)陨石中难熔亲铁元素的分布及其宇宙化学意义；(3)陨石中稀土元素（ree）、Th和U的分布及其宇宙化学意义；(4)发展适用于陨石样品的分析技术。对于第一个课题，我们建立了一种测定单个50 ~ 100 mg样品中4种卤素的分析方法，并将其应用于球粒陨石样品。我们还研究了Cl、Br和I在球粒陨石中的分布，发现I在辉石和/或斜长石中有一定的分布，与Cl和Br不同。这一观察对于考虑I的宇宙化学行为似乎非常重要，而这一行为尚未得到很好的描述。对于第二个主题，我们测定了火星陨石中的难熔亲铁元素，并观察到火星陨石中含有这些元素的水平为10^<-2>至10^<-3> x Cl。这可以理解为在核心形成后添加亲铁元素作为最后的贴面。第三个课题刚刚完成，与这个课题相关的论文将很快准备好。在本课题中，我们测定了球粒中的稀土、钍和铀，并观察到它们的丰度随母体热变质活动的变化而变化。

This year is the last year of the project. In this year, we have conducted the following research subjects ; (i) establishment of the analytical technique for four halogens in solid silicate materials and its application to meteorite samples, (ii) distribution of refractory siderophile elements in meteorites and its cosmochemical implications, (iii) distribution of rare earth elements (REEs), Th and U in meteorites and its cosmochemical implications, and (iv) development of analytical techniques applicable to meteorite samples. For the first subject, we established an analytical method for determining four halogens in a single sample weighing 50 to 100 mg and applied it to chondritic meteorite samples. We also investigated the distribution of Cl, Br and I in chondritic meteorites and observed that I is distributed in pyroxene and/or plagioclase to some extent, being different from Cl and Br. This observation seems to be very important in considering cosmochemical behavior of I, which has not been well described yet. For the second subject, we determined refractory siderophile elements in martian meteorites and observed that martian meteorites contain these elements at a level of 10^<-2> to 10^<-3> x Cl. This is understood in terms of an addition of siderophile elements as a last veneer after the formation of core. The third subject has just completed and the paper related with this subject will be prepared soon. In this subject, we determined REEs, Th and U in chondrules and observed that their abundances change in accordance with the activity of thermal metamorphism in the parent body.