Comparation of petrography and mineral chemistry characteristics among olivine and Ca,Al-rich assemblages
Dai Deqiu1,2, Chen Xinyue1, Yang Rongfeng1,3
1. Institute of Geology, Hunan University of Science and Technology, Xiangtan, Hunan 411201;
2. Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002;
3. Hunan Provincial Key Laboratory of Shale Gas Resource Utilization, Xiangtan, Hunan 411201
Ca-, Al-rich inclusions, chondrules and amoeboid olivine aggregates are the early assemblages of the solar nebula.4 olivine and Ca, Al-rich assemblages were studied to compare with their petrography and mineral chemistry. The petrography and mineral chemistry characteristics argues that spinel-pyroxene-rich inclusion embedded in olivine and Ca, Al-rich amoeboid olivine aggregates are likely assemblages of solar nebular condensates.The plagioclase-olivine inclusions(POIs)and Ca-, Al-rich chondrules were crystallized from melts. The characteristics of mineral modal compositions of POIs and Ca-, Al-rich chondrules argues they probably represent intermediate assemblages between typical refractory inclusions and chondrules.Spinel in amoeboid olivine aggregates(GRV022459-2C1)is the most remarkably FeO-rich in all assemblages, and it indicates alteration of the aggregate happened under high oxygen fugacity.Chondrules and coarse-grained Ca-, Al-rich inclusions are probably crystallized from melt in the same affair.The coarse-grained Ca-, Al-rich inclusions form probably the reservoir of Ca-, Al-rich prior matters, and Mg, Fe silicate chondrules form in the reservoir of Ca-, Al-poor prior matters.POIs and Ca-, Al-rich chondrules form the district between coarse-grained inclusions and Mg, Fe silicate chondrules.