| 陨石中的太阳系外物质及其同位素异常 |
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| 引用本文： | 林杨挺,王世杰.陨石中的太阳系外物质及其同位素异常[J].矿物学报,2000,20(1):1-8. |
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| 作者姓名： | 林杨挺 王世杰 |
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| 作者单位： | 1. 中国科学院广州地球化学研究所,广州,510640
2. 中国科学院地球化学研究所环境地球化学国家重点实验室,贵阳,550002 |
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| 基金项目： | 国家自然科学基金!(批准号 :49873 0 2 8和 49773 2 0 4)，中国科学院九五重点项目!(批准号 :KZ95 2 J1 413 ) |
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| 摘 要： | 到目前为止从陨石中分离出的太阳系外物质有金刚石、碳化硅、石墨、Ｓｉ３Ｎ４、刚玉及尖晶石等。除金刚石为纳米级大小外，其他为微米和次微米级颗粒。这些太阳系外物质主要存在于原始的球粒陨石的基质中，并通过化学分离的方法获得。金刚石携带分别由ｐ－过程和ｒ－过程产生的Ｘｅ同位素组分（Ｘｅ－ＨＬ），其源区可能提超新星。绝大部分碳化硅相对于太阳系物质富＾２９．３０Ｓｉ和＾１３Ｃ，贫＾１５Ｎ，并携带ｓ－过程产生的各
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| 关 键 词： | 同位素异常 太阳系外物质 陨石 |
PRESOLAR GRAINS AND THEIR ISOTOPIC ANORMALIES IN METEORITES |
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| Lin Yangting,Wang Shijie.PRESOLAR GRAINS AND THEIR ISOTOPIC ANORMALIES IN METEORITES[J].Acta Mineralogica Sinica,2000,20(1):1-8. |
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| Authors: | Lin Yangting Wang Shijie |
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| Abstract: | Study on presolar grains including diamond, silicon carbide, graphite, nierite (Si 3N 4), corundum and spinel isolated from meteorites is summarized in this paper. Except for nanometer sized diamond, the other grains are micrometers to submicrometers in size. The presolar grains survived mainly in the fine grained matrix of primitive chondrites and were isolated by chemical treatments. Diamond contains Xe isotopes (Xe HL) typically produced in p and r processes, probably formed in supernovae. Mainstream silicon carbides are enriched in 29,30 Si and 13 C, but depleted in 15 N. They also contain various s process products, consistent with calculations of AGB stars. Other silicon carbides exhibit much larger isotopic anomalies and are classified as groups X, Y, Z and AB. Among them, group X of SiC is characterized by enrichment of 29 Si and daughter isotopes of various short lived nuclides, suggesting an origin from supernovae. Graphite can be divided into four density fractions with distinct isotopic compositions. They may form in AGB stars, novae and supernovae, respectively. Si 3N 4 is similar to X SiC in isotopic composition. Corundum is classified as four groups based on their oxygen isotopic composition. AGB and red giant stars are possible sources for the oxide. More comprehensive study of presolar grains, especially, discovery of the other types of oxides and silicates, isotopic analyses of individual submicrometer sized grains and distribution of presolar grains among various chemical groups and petrographic types of chondrites will supply with new information on nucleosynthesis, stellar evolution and formation of the solar nebula. |
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| Keywords: | isotopic anomaly presolar grain meteorite |
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