STUDY OF EXTRA-SOLAR MATERIALS ON THE VIEW OF OXYGEN ISOTOPES

本项目研究了阿连德陨石中富钙铝包裹体(CAI)中的太阳外物质。主要研究内容如下：(1)利用电子探针分析仪生成了CaI矿物的浓度图。(2)研制了一种用于二次离子质谱仪(SIMS)的新型负金属离子源(Blake-V)，用于精确分析CaI矿物的氧同位素。(3)利用Blake-V离子源的Au~+一次束流，建立了一种精确的CaI矿物氧同位素分析方法。(4)CaI矿物内部氧同位素分布均匀，而矿物间氧同位素分布不均匀。这种关系不能用矿物间的化学平衡来解释。(5)CaI的成因可解释为：(A)CaI中的尖晶石颗粒在超新星残留物中结晶。(B)在太阳星云和太阳星云最外缘残留物之间的混合气体中产生了辉石颗粒。(C)太阳星云中析出了过冷液，液中结晶出黄长石和斜长石颗粒。

Extra-solar materials in Ca, Al-rich inclusions (CAIs) from Allende meteorite have been investigated in this projects. The project may be summarized as follows:(1)Concentration mapping of CAI minerals has been generated by electron micro probe analyzer. The results show crystallization sequences of the minerals.(2)A novel negative-metal ion source (BLAKE-V) for secondary ion mass spectrometry (SIMS) was developed for precise oxygen isotope analyses of CAI minerals.(3)A precise oxygen isotope analysis in CAI minerals was developed using the Au^- primary beam from the BLAKE-V ion source.(4)Oxygen isotope distribution was homogeneous in intra-mineral in CAI, whereas was quite heterogeneous among minerals. Such relationship cannot be interpreted by chemical equilibrium among minerals.(5)The origin of CAI may be interpreted as follows: (a)Spinel grains in CAIs ware crystallized in super novae remnant. (b)pyroxene grains were generated in the mixing gas between the solar nebula and the remnant at the most outer rim of the solar nebulae. (c)In the solar nebulae super cooling liquid was precipitated, and melilite and anorthite grains were crystallized in the liquid.