Bulk compositions of metallic Fe-Ni of chondrites: Constraints on fractionation of siderophile and chalcophile elements  

作　　者：XU Lin LIN Yangting WANG Shijie OUYANG Ziyuan 

机构地区：[1]Key Laboratory of the Study of Earth＇s Deep Interior, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beifing 100029, China [2]National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, China [3]Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China

出　　处：《Chinese Journal Of Geochemistry》2009年第3期271-278,共8页中国地球化学学报

基　　金：supported by the Pilot Project of Knowledge Innovation Program of Chinese Academy of Sciences (Grant No. KZCX2-YW-110);the IPY China Project of the Ministry of Finance of China (Grant No. IPY2008-P050400102-01)

摘　　要：Bulk compositions of metallic Fe-Ni from two equilibrated ordinary chondrites, Jilin (H5) and Anlong (H5), and two unequilibrated ones, GRV 9919 (L3) and GRV 021603 (H3), were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). The CI-, Co-normalized abundances of siderophile and chalcophile elements of metallic Fe-Ni from the unequilibrated ordinary chondrites correlate with 50% condensation temperatures (i.e., volatility) of the elements. The refractory siderophile elements (i.e., platinum group elements, Re), Au, Ni and Co show a flat pattern (1.01×CI Co-normalized), while moderate elements (As, Cu, Ag, Ga, Ge, Zn) decrease with volatility from 0.63×CI (Co-normalized, As) to 0.05×CI (Co-normalized, Zn). Cr and Mn show deficit relative to the trend, probably due to their main partition in silicates and sulfides (nonmagnetic). Metallic Fe-Ni from the equilibrated ordinary chondrites shows similar patterns, except for strong deficit of Cr, Mn, Ag and Zn. It is indicated that these elements were almost all partitioned into silicates and/or sulfides during thermal metamorphism. The similar deficit of Cr, Mn, Ag and Zn was also found in iron meteorites. Our analyses demonstrate similar behaviors of W and Mo as refractory siderophile elements during condensation of the solar nebula, except for slight depletion of Mo in the L3 and H5 chondrites. The Mo-depletion of metallic Fe-Ni from GRV 9919 (L3) relative to GRV 021603 (H3) could be due to a more oxidizing condition of the former than the latter in the solar nebula. In contrast, the Mo-depletion of the metallic Fe-Ni from the H5 chondrites may reflect partition of Mo from metal to silicates and/or sulfides during thermal metamorphism in the asteroidal body.Bulk compositions of metallic Fe-Ni from two equilibrated ordinary chondrites, Jilin （H5） and Anlong （HS）, and two unequilibrated ones, GRV 9919 （L3） and GRV 021603 （H3）, were analyzed by inductively coupled plasma mass spectrometry （ICP-MS）. The CI-, Co-normalized abundances of siderophile and chalcophile elements of metallic Fe-Ni from the unequilibrated ordinary chondrites correlate with 50% condensation temperatures （i.e., volatility） of the elements. The refractory siderophile elements （i.e., platinum group elements, Re）, Au, Ni and Co show a flat pattern （1.01×CI Co-normalized）, while moderate elements （As, Cu, Ag, Ga, Ge, Zn） decrease with volatility from 0.63×CI （Co-normalized, As） to 0.05×CI （Co-normalized, Zn）. Cr and Mn show deficit relative to the trend, probably due to their main partition in silicates and sulfides （nonmagnetic）. Metallic Fe-Ni from the equilibrated ordinary chondrites shows similar patterns, except for strong deficit of Cr, Mn, Ag and Zn. It is indicated that these elements were almost all partitioned into silicates and/or sulfides during thermal metamorphism. The similar deficit of Cr, Mn, Ag and Zn was also found in iron meteorites. Our analyses demonstrate similar behaviors of W and Mo as refractory siderophile elements during condensation of the solar nebula, except for slight depletion of Mo in the L3 and H5 chondrites. The Mo-depletion of metallic Fe-Ni from GRV 9919 （L3） relative to GRV 021603 （H3） could be due to a more oxidizing condition of the former than the latter in the solar nebula. In contrast, the Mo-depletion of the metallic Fe-Ni from the H5 chondrites may reflect partition of Mo from metal to silicates and/or sulfides during thermal metamorphism in the asteroidal body.

关 键 词：亲硫元素 球粒陨石 金属铁 铁元素 成分 散装 分馏 镍 

分 类 号：TQ171.415[化学工程—玻璃工业] P185.83[化学工程—硅酸盐工业]