ADVANCES IN POLAR SCIENCE ›› 2013, Vol. 25 ›› Issue (4): 436-448.DOI: 10.3724/SP.J.1084.2013.00436

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THE RESEARCH OF CHONDRULES TYPES OF KUMTAG 004 CHONDRITE FROM XINJIANG AND THE APPLICATION OF CHONDRULES CLASSIFICATION SCHEMES

Zhang Chuantong1,Miao Bingkui1,He Huaiyu2   

  1.  
    1Key Laboratory of Geological Engineering Centre of Guangxi Province, Guilin Univerity of Technology, Guilin 541004, China;
    2Key Laboratory of the Earth’s Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029,China
  • Received:2013-09-22 Revised:2013-10-30 Online:2013-12-30 Published:2013-12-30

Abstract: Chondrules are the main constituents of chondrites. There are 3 main kinds of classification schemes of chondrules currently, i.e., texture, FeO-SiO2 and M-FeO-CaO. The texture classification depends on texture and morphology highly but chemical composition unclosely. The FeO-SiO2 and M-FeO-CaO classification schemes introduce mineral chemical criteria onto traditional texture taxonomic scheme and can further insight into the physical-chemical process occurring in the solar nebula. But the practical applications are too few for the latter two schemes. The chondrules in Kumtag 004 (L4, S4, W3) which from the new desert meteorites enrichment region-Kumtag desert of Xinjiang have been classified base on the three classification schemes after observing structure and analyzing composition. Then we discuss the merit and demerit of the FeO-SiO2 and M-FeO-CaO classification schemes and the application range. For the FeO-SiO2 taxonomic scheme that can apply to porphyritic chondrules as well as non-porhyritic chondrules, wo suggest that FeO=7.5% (wt%) is the boundary between type I and II chondrules and so are 47% and 53%(SiO2, wt%) for type A, AB and B chondrules. A approximate partition is proposed for the type A1(FeO<1,CaO>1), A2(FeO≈1-3,CaO<0.5), A5(FeO≈11-14,CaO≈0.3-0.9) and B(FeO>3,CaO<0.5) chondrules for the M-FeO-CaO classification scheme based on the pyroxene (FeO and CaO, wt%).

Key words: classification for chondrule, texture, chemical composition, Kumtag 004 chondrite