Cosmochemical and isotopic study of the origin and evolution of chondrites and achondrites, their genetic relationship and timescales.

为了获得原始和分化陨石形成的时间、起源、演化及其成因关系的新证据，我们对球粒陨石和无球粒陨石进行了化学、岩石学和同位素分析。结果表明：(1)在神户（CK）陨石的国际联合研究中，我们获得了独特的稀土元素模式和详细的化学和岩石学特征，这些特征限制了CK球粒陨石的星云分馏和陨石母体过程，导致了陨石的硅酸盐变暗。用U-Pb法和Rb-Sr法对该陨石进行了年龄测定，表明CK球粒陨石母体的热历史复杂。(2)对Allende （CV）陨石中最纯的基体材料和球粒进行了REE和Rb-Sr同位素分析。稀土元素分析结果表明，基质的前体是由星云过程形成的。在Allende Rb-Sr体系中新发现4.4Ga蚀变事件。(3)对5个针孔岩进行了精确的Sm-Nd同位素分析，其中1个针孔岩具有明显的年轻年龄（4.13±0.10Ga），表明母体发生了年轻的热事件。(4)建立了低Pb空白U-Pb定年技术，获得了3颗新发现的南极火星陨石的精确U-Pb年龄、Sm-Nd、Rb-Sr年龄和REE谱图。(5)在原始陨石中发现了源自恒星过程的Mo同位素异常。建立了精确的Cr和Ba同位素分析技术，并在原始和分化陨石中发现了新的同位素异常。(6)利用热电离质谱（TIMS）对阿连德岩和9块标准岩进行了氯同位素的精确分析。我们还建立了Cl的高灵敏度阴性TIMS。

In order to obtain new evidences constraining the timing, origin and evolution of primitive and differentiated meteorites and their genetic relationships, we have carried out chemical, petrological and isotopic analyses for chondrites and achondrites. Results are summarized bellow :(1)Under international consortium for the Kobe (CK) meteorite, we obtained a unique REE pattern and detailed chemical and petrological features, which constrains nebular fractionations and meteorite parent body processes of CK chondrites yielding silicate-darkening of the meteorites. The age determination by U-Pb and Rb-Sr methods were carried out for the meteorite, indicating complicated thermal histories of CK chondrite parent body.(2)REE and Rb-Sr isotopes were analyzed for the most pure matrix materials or chondrules from the Allende (CV) meteorite, respectively. REE results suggest that the precursor of matrix formed by nebular processes. The 4.4Ga alteration event was newly discovered from Rb-Sr system of Allende.(3)The precise Sm-Nd isotopic analyses were carried out for 5 acapulcoites : We obtained a significantly young age (4.13±0.10Ga) for one acapulcoite, indicating young thermal event on the parent body.(4)The low Pb blank technique for U-Pb dating was established and precise U-Pb ages as well as Sm-Nd and Rb-Sr ages and REE patterns were obtained for three newly found Antarctic Martian meteorites.(5)The Mo isotopic anomalies derived from stellar processes were discovered in primitive meteorites. Precise Cr and Ba isotopic analysis techniques were established and new isotopic anomalies were found for primitive and differentiated meteorites.(6)Precise chlorine isotopic analyses were carried out for Allende and 9 standard rocks using thermal ionization mass spectrometry (TIMS). We also established a high sensitivity negative TIMS for Cl.