球粒陨石难熔包体中贵金属的矿物岩石学分析:对太阳星云演化的启示

The Petrology and Mineralogy Analysis of Noble Metal Alloys in the Inclusions of Chondrite:An Implication on the Evolution of the Solar Nebula

球粒陨石中的富钙富铝难熔包体(Ca,Al-rich Inclusion,CAI)是太阳系最早形成的物体,保留了太阳星云早期的原始信息,但深入研究发现许多难熔包体具有复杂的演化历史,包括部分熔融和后期变质作用等.针对难熔包体中更为难熔、化学性质更为稳定的贵金属颗粒进行天体化学研究,选取CV群碳质球粒陨石NWA 2140,对其CAI中的贵金属颗粒进行岩石学观察及化学成分测定.根据得到的成分分析结果,能大致推出包体经历过的热力学历程,辨识出两类贵金属合金颗粒,这两类贵金属分别为早期冷凝产物和原生金属的后期蚀变产物.

The Ca, Al-rich Inclusions （CAIs） in chondrites are believed to be the first solids to have formed in the solar system which retain the original information of the early solar nebula. However, in-depth researches reveal that most inclusions had experienced a complex history involving partial melting and secondary alteration. Studies on astrochem- istry are focused on refractory and chemically stable noble metal alloys in the CAI of a CV meteorite （NWA 2140）. The petrology and mineralogy of the alloys are analyzed. The com- positional data analysis of the component can imply the thermal history of the CAI. Two kinds of noble metal alloys are identified, the primary condensates and secondary alteration products of pre-existing metals, respectively.