Bulk concentrations of Ir, Os, Co and other siderophile elements of metal phase in chondrites increase significantly with degree of oxidation, which together with Co - content of kamacite and Fa - content of olivine, ...Bulk concentrations of Ir, Os, Co and other siderophile elements of metal phase in chondrites increase significantly with degree of oxidation, which together with Co - content of kamacite and Fa - content of olivine, reveal a continuous variation of redox in chondrites. Intermediate groups of E/H, H/L , L/LL, and LL/C, lying between E and H , H and L, L and LL , LL and C, respectively, were proposed based on Co content in kamacite, Fa value of olivine, Fs value of low - Ca pyroxene, bulk concentrations of Ir, Os and Co of metal phase and other taxonomic parameters. The discovery of intermediate groups increases the number of chemical groups of chondrites from 9 to 13. Both variation of redox in chondrites and presence of the intermediate groups of chondrites suggest a continuous chemical fractionation in the primordial solar nebula.展开更多
Based on the studies of meteorites,theauthors introduce the formation and evolutionof the solar system,including condensation,heating and alteration in the solar nebula,thermal metamorphism,igneous fractionationand sh...Based on the studies of meteorites,theauthors introduce the formation and evolutionof the solar system,including condensation,heating and alteration in the solar nebula,thermal metamorphism,igneous fractionationand shock metamorphism in parent bodies ofmeteorites.Heterogeneities in chemical展开更多
The Qingzhen and Yamato 691 (EH3) enstatite chondrites, which formed under extremely reducing condi-tions, are studied using the scanning electron microscope and electron probe microanalyzer. Both meteorites contain F...The Qingzhen and Yamato 691 (EH3) enstatite chondrites, which formed under extremely reducing condi-tions, are studied using the scanning electron microscope and electron probe microanalyzer. Both meteorites contain FeO-rich silicates and minor Ca, Al-rich inclusions. Most FeO-rich silicates are Ca-poor pyroxenes and occur as frag-ments in matrix. A few grains of FeO-rich silicates were found in chondrules, and FeO-rich olivine is rare. In Qingzhen, FeO-rich silicates commonly contain abundant dust-like Ni-poor metals, which probably formed through reduction of FeO. In contrast, only a few fragments of FeO-rich silicates in Yamato 691 enclose dust-like metals. This difference is consistent with a more reducing condition of Qingzhen than Yamato 691. Ca, Al-rich inclusions have similar modal compositions and mineral chemistry as their counterparts in carbonaceous chondrites. We suggest that (1) the FeO-rich silicates probably formed in oxidized regions of the solar nebula, and then moved into the展开更多
In three polished thin sections of Yamato 791717 (CO3), fifty\|five Ca, Al\|rich inclusions were found, which include two hibonite\|bearing, eight melilite\|rich and forty\|five spinel\|pyroxene inclusions. Based on t...In three polished thin sections of Yamato 791717 (CO3), fifty\|five Ca, Al\|rich inclusions were found, which include two hibonite\|bearing, eight melilite\|rich and forty\|five spinel\|pyroxene inclusions. Based on the petrography and mineral chemistry of the inclusions, it is proposed that the melilite\|rich inclusions and spinel\|pyroxene inclusions condensed in the solar nebula, and the hibonite\|bearing inclusions crystallized from melts. The heavy alteration of the inclusions in Yamato 791717, which probably took place under a very oxidizing condition in the solar nebular, is also confirmed.展开更多
基金Supported by State Antarctic CommitteeChinese Academy of Sciences
文摘Bulk concentrations of Ir, Os, Co and other siderophile elements of metal phase in chondrites increase significantly with degree of oxidation, which together with Co - content of kamacite and Fa - content of olivine, reveal a continuous variation of redox in chondrites. Intermediate groups of E/H, H/L , L/LL, and LL/C, lying between E and H , H and L, L and LL , LL and C, respectively, were proposed based on Co content in kamacite, Fa value of olivine, Fs value of low - Ca pyroxene, bulk concentrations of Ir, Os and Co of metal phase and other taxonomic parameters. The discovery of intermediate groups increases the number of chemical groups of chondrites from 9 to 13. Both variation of redox in chondrites and presence of the intermediate groups of chondrites suggest a continuous chemical fractionation in the primordial solar nebula.
文摘Based on the studies of meteorites,theauthors introduce the formation and evolutionof the solar system,including condensation,heating and alteration in the solar nebula,thermal metamorphism,igneous fractionationand shock metamorphism in parent bodies ofmeteorites.Heterogeneities in chemical
基金This work was supported by the National Science Fund for Distinguished Young Scholars (Grant No. 40025311).
文摘The Qingzhen and Yamato 691 (EH3) enstatite chondrites, which formed under extremely reducing condi-tions, are studied using the scanning electron microscope and electron probe microanalyzer. Both meteorites contain FeO-rich silicates and minor Ca, Al-rich inclusions. Most FeO-rich silicates are Ca-poor pyroxenes and occur as frag-ments in matrix. A few grains of FeO-rich silicates were found in chondrules, and FeO-rich olivine is rare. In Qingzhen, FeO-rich silicates commonly contain abundant dust-like Ni-poor metals, which probably formed through reduction of FeO. In contrast, only a few fragments of FeO-rich silicates in Yamato 691 enclose dust-like metals. This difference is consistent with a more reducing condition of Qingzhen than Yamato 691. Ca, Al-rich inclusions have similar modal compositions and mineral chemistry as their counterparts in carbonaceous chondrites. We suggest that (1) the FeO-rich silicates probably formed in oxidized regions of the solar nebula, and then moved into the
基金Supported by the National Key Research and Development Program of China(Grant No.2016YFA0400200)the National Natural Science Foundation of China(Grant No.11773075)the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.2016288)。
文摘In three polished thin sections of Yamato 791717 (CO3), fifty\|five Ca, Al\|rich inclusions were found, which include two hibonite\|bearing, eight melilite\|rich and forty\|five spinel\|pyroxene inclusions. Based on the petrography and mineral chemistry of the inclusions, it is proposed that the melilite\|rich inclusions and spinel\|pyroxene inclusions condensed in the solar nebula, and the hibonite\|bearing inclusions crystallized from melts. The heavy alteration of the inclusions in Yamato 791717, which probably took place under a very oxidizing condition in the solar nebular, is also confirmed.
