富钙长石-橄榄石型包体与典型富Ca,Al包体的矿物岩石学特征对比研究

本文研究了2个富钙长石-橄榄石型包体和2个富黄长石-尖晶石型和富尖晶石-辉石型包体（分别来自宁强和南极格罗夫山碳质球粒陨石）的矿物岩石学特征,并对它们进行了对比。富钙长石-橄榄石型包体的矿物模式组成具有富橄榄石和缺失黄长石的特征,其可能是球粒和典型难熔包体之间的中间产物,是认识它们之间相互关系的钥匙。矿物岩石学特征表明富黄长石-尖晶石型和富尖晶石-辉石型包体可能是星云直接凝聚的产物,而富钙长石-橄榄石型包体经历过熔融结晶过程。富钙长石-橄榄石型包体的初始物质可能是富Al的球粒或含难熔组分的蠕虫状橄榄石集合体。矿物化学组成对比研究发现,GRV 022459-RI6中的尖晶石具有最富FeO的特征,表明包体的蚀变可能发生在高氧逸度的星云环境。

Comparison of Petrography and Mineral Chemistry Characters between Plagioclase Olivine Inclusions and Typical Ca,Al-rich Inclusions

Petrography and mineral chemistry of two plagioclase-olivine inclusions(POIs) and two typical Ca-,Al-rich inclusions(one melilite-spinel-rich inclusion and one spinel-pyroxene-rich inclusion) from Ningqiang and the Grove Mountains(GRV) carbonaceous chondrites,respectively,were studied.POIs have the characters of mineral modal compositions of olivine-rich and melitite-Absence,and they probably represent intermediate assemblages between typical refractory inclusions and chondrules.The petrography and mineral chemistry characters indicate that melilite-spinel-rich inclusion and spinel-pyroxene-rich inclusion are likely assemblages of solar nebular condensates,and POIs are crystallized from melts.The prior matters of POIs are probably the Al-rich chondrules or the refractory mineral-bearing amoeboid olivine aggregates.Spinel in GRV 022459-RI6 is the most remarkably FeO-rich in four Ca-,Al-rich inclusions,and it indicates that alteration of the inclusion happened under high oxygen fugacity.