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Geochemical Study on the Oldest Halite Fossil in the Solar System

太阳系最古老的石盐化石的地球化学研究

基本信息

批准号：
13440165
负责人：
NAGAO Keisuke
金额：
$ 9.15万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13440165/
关键词：
noble gas isotopes halite halogens neutron irradiation I-Xe age ^<40>Ar-^<39>Ar age Zag meteorite formation age 希ガス同位体ハロゲン I-Xe年代 Zag隕石希ガス質量分析 Ar-Ar年代 Allende隕石顕微ラマン分光ダイオードレーザー

项目摘要

Halogens and their crystals (halide) have been investigated in Zag and other halogen containing meteorites by detecting halogen-derived noble gas isotopes ^<80>Kr, ^<82>Kr and ^<128>Xe^<129>Xe from extinct nuclide was ^<129>I also measured in these meteorites. Halide crystals are dark phase portion of the Zag meteorite. Size of most crystals are estimated to be smaller than 0.1 mm, which would be surrounded by silicates insoluble in water. Halogens are also concentrated in small materials in Yamato-74191 (L3.6) meteorite. The halogen enrichments in these meteorite are likely resulted by liquid water with high concentrations of halogens presented on their parent planetesimals. Though origin of the waters is not clear, they might have been brought through bombardment by water containing objects such as carbonaceous chondrites or comets.To study the event concerning the halogen enrichments, we constructed noble gas extraction and purification line for noble gas analysis of neutron irradiated meteorites. Modification of VG3600 noble gas mass spectrometer used for ^<40>Ar-^<39>Ar dating was carried out to improve sensitivity and stability of the mass spectrometer in the Radioisotope Center, University of Tokyo. Combining the noble gas line and the mss spectrometer, I-Xe dating of meteorites can be measurable for the first time in Japan. This method began to clarify the timing of halogen enrichment process in meteorites.

通过检测来自灭绝核素的^<80>Kr、^<82>Kr和^<128>Xe^<129>Xe，在Zag和其他含卤素陨石中研究了卤素及其晶体（卤化物），也在这些陨石中测量了^<129>I。卤化物晶体是 Zag 陨石的暗相部分。大多数晶体的尺寸估计小于 0.1 毫米，被不溶于水的硅酸盐包围。卤素也集中在 Yamato-74191 (L3.6) 陨石的小物质中。这些陨石中的卤素富集可能是由其母星子上存在高浓度卤素的液态水造成的。虽然这些水的来源尚不清楚，但它们可能是由碳质球粒陨石或彗星等含有水的物体轰击而来。为了研究卤素富集事件，我们建造了稀有气体提取和纯化线，用于中子辐照陨石的稀有气体分析。东京大学放射性同位素中心对VG3600用于^<40>Ar-^<39>Ar测年的惰性气体质谱仪进行了改造，以提高质谱仪的灵敏度和稳定性。结合惰性气体线和MSS光谱仪，在日本首次可以测量陨石的I-Xe测年。该方法开始阐明陨石中卤素富集过程的时间。