Study on Formational Environment of Anomalous Carbonaceous Chondrites

异常碳质球粒陨石的形成环境研究

• 批准号: 02453047
• 负责人: IKEDA Yukio
• 金额: $ 3.78万
• 依托单位: IBARAKI University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1990
• 资助国家: 日本
• 起止时间: 1990 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-02453047/
• 关键词: Carbonaceous Chondrites; Hydrous Minerals; CM group; CI group; Nebular Gas; Alteration; Talc; Serpentine; Belgicaー7904隕石; コンドリュ-ル; マトリックス; 加水反応; 原始太陽系星雲; 母天体; Yamatoー82162隕石; Yamatoー86720隕石; 隕石母天体; ペリクレイス; 酸素同位体組成

Three anomalous Antarctic meteorites, Yamato-82162, Yamato-86720, and Belgica-7904 have characteristics of both CI and CM chondrite groups, and were classified as CY group. They include abundant phyllosilicates, chemical compositions of which differ from those of CI and CM groups. Oxygen isotopic compositions of the CY bulk meteorites are also different from those of CI and CM chondrites. Metallic phases in the CY group coexist with wustite and magnetite, suggesting that the components of CY group condensated from an oxidized nebular gas which had depleted in hydrogen and helium in comparison to the solar gas.Pyroxene, plagioclase, and groundmass glass in chondrules of CY chondrites reacted with the oxidized nebular gas to form talc-rich phyllosilicates at temperatures lower than 600K, and later serpentine was produced from olivine at temperatures of about 300K.The phyllosilicates of CY group seems to have formed under an environment condition between those of CI and CM chondrites; Phyllosilicates in CM chondrites were produced by the parent body process without remarkable reaction with the nebular gas, those of CY group were formed by nebular process with remarkable reaction to produce the hydrous minerals, and those of CI group by both nebular and parent body processes. In addition, the CY group chondrites have experienced dehydration by shock heating on their parent body.

三颗异常南极陨石Yamato-82162、Yamato-86720和Belgica-7904同时具有CI和CM球粒陨石群的特征，被归为CY群。它们包括丰富的层状硅酸盐，其化学组成不同于Cl和CM族。CY块体陨石的氧同位素组成也不同于CI和CM陨石。CY组中的金属相与方铁矿和磁铁矿共存，表明CY组的组分是从氧化的星云气体中凝聚而成的，与太阳气体相比，这种气体中的氢和氦已经减少。CY组陨石球粒中的辉石、斜长石和基质玻璃与氧化的星云气体在低于600 K的温度下反应，形成富滑石的层状硅酸盐，后来在300 K左右由橄榄石生成蛇纹石。CY组层状硅酸盐的形成环境介于CI和CM组之间; CM榴辉岩中的层状硅酸盐是由母体过程产生的，与星云气体没有明显的反应，CY组为星云过程形成，并有明显的反应生成含水矿物，CI组为星云过程和母体过程共同作用形成。此外，CY组的幼鱼经历了母体休克加热引起的脱水。

项目成果

Y.Ikeda and H. Kojima: "Terrestrial Alteration of Fe-Ni Metals in Antarctic Ordinary Chondrites and the Relationship to their Terrestrial Ages" Proceedings of the NIPR Symposium on Antarctic Meteorites. No.4. 307-318 (1991)

Y.Ikeda 和 H. Kojima：“南极普通球粒陨石中铁镍金属的陆地蚀变及其与陆地年龄的关系”南极陨石 NIPR 研讨会论文集。

M.Kimura: "Mineralogy and Petrology of Anomalous Carbonaceous chondrite Belgicaー7904" Proceedings of NIPR Symp.Antarct.Meteorites. 5. (1992)

M.Kimura：“异常碳质球粒陨石 Belgica-7904 的矿物学和岩石学”NIPR Symp.Antarct.Meteorites 5 的论文集。(1992)

M.Kimura: "Mineralogy and Petnelogy of Anomalous Carbonaceous Chondrite Belgica-7904:Genetic Relation sihps between the Components." Proceadiugu of the NIPR Symposium on Autarctic Meteorites. 5. 74-119 (1992)

M.Kimura：“异常碳质球粒陨石 Belgica-7904 的矿物学和岩石学：成分之间的遗传关系。”

Y.Ikeda: "An Overview of ro Research Consortium, "Antarctic Carbonaceous Chondrites with CI Affinities, Yamato-86720, Yamato-82162, and Belgica-7904"." Proceedings of Ke NIPR Symposium in Antarctic Meteorites. No.5. 49-73 (1992)

Y.Ikeda：“ro 研究联盟概述，“具有 CI 亲和力的南极碳质球粒陨石，Yamato-86720、Yamato-82162 和 Belgica-7904”。

Y.Ikeda: "Petrology and Mineralogy of the Yamato-82162 Chondrite(CI)" Proceedings of the NIPR Symposium on Antarctic Meteorites. 4. 187-225 (1991)

Y.Ikeda：“Yamato-82162 球粒陨石 (CI) 的岩石学和矿物学”南极陨石 NIPR 研讨会论文集。