LA-ICP-MS Analysis of Trace Elements in Yanzhuang
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By taking the whole-rock melt phase, silicate melt phase, and FeNi metal phase in the Yanzhuang chondrite as research objects, this paper conducted trace element measurement of each phase using the LA-ICP-MS technique. The results show that (1) during the shock-induced melting of the Yanzhuang chondrite, the siderophile elements Fe, Ni, and Co are mainly concentrated in the FeNi metal blobs embedded in the whole-rock melt phase, while the elements Cr, V, Ti, and Mn are transferred into pyroxene crystallizing from silicate melt to substitute Al3+; (2) the chalcophile elements Cu, Ga, and Pb are also concentrated in the FeNi metal phase, while the volatile element Zn was partly lost upon melting, but it was mainly transferred into the microcrystalline pyroxene and olivine crystallizing from the silicate melt to substitute Fe2+; (3) the lithophile elements Sc, Zr, Nb, and Ta are basically enriched in the silicate melt phase, but the differentiation degrees of Nb and Ta are low, and the Nb/Ta ratio in the FeNi metal phase is lower than that in the silicate melt phase by more than 1 time, indicating that the activization ability of Nb is higher than Ta upon high P-T melting; (4) the rare earth elements (REE) patterns of whole-rock melt and silicate melt phases hold the characteristic features of Oddo–Harkins rule and show the tendency of enrichment of light REE and that of depletion of heavy REE, but the FeNi metal phase displays the tendency of depletion of LREE, and its total REE content is lower than that in the silicate melt phase by about three times. This indicates that REE, especially the LREE, are enriched in the silicate melt phase; and (5) Pt-group elements are moved to the FeNi metal phase after shock melting.
KeywordsYanzhuang chondrite Shock melting FeNi metal Trace element LA-ICP-MS
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