Precise Determination of Sm and Nd Concentrations and Nd Isotopic Compositions in Highly Depleted Ultramafic Reference Materials |
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| Authors: | Zhuyin Chu Jinghui Guo Yueheng Yang Liang Qi Chaofeng Li |
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| Institution: | 1. State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, , Beijing, 100029 China;2. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, , Guiyang, 550002 China |
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| Abstract: | In this study, a high‐precision method for the determination of Sm and Nd concentrations and Nd isotopic composition in highly depleted ultramafic rocks without a preconcentration step is presented. The samples were first digested using the conventional HF + HNO3 + HClO4 method, followed by the complete digestion of chromite in the samples using HClO4 at 190–200 °C and then complete dissolution of fluoride formed during the HF decomposition step using H3BO3. These steps ensured the complete digestion of the ultramafic rocks. The rare earth elements (REEs) were separated from the sample matrix using conventional cation‐exchange chromatography; subsequently, Sm and Nd were separated using the LN columns. Neodymium isotopes were determined as NdO+, whereas Sm isotopes were measured as Sm+, both with very high sensitivity using single W filaments with TaF5 as an ion emitter. Several highly depleted ultramafic rock reference materials including USGS DTS‐1, DTS‐2, DTS‐2b, PCC‐1 and GSJ JP‐1, which contain extremely low amounts of Sm and Nd (down to sub ng g?1 level), were analysed, and high‐precision Sm and Nd concentration and Nd isotope data were obtained. This is the first report of the Sm‐Nd isotopic compositions of these ultramafic rock reference materials except for PCC‐1. |
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| Keywords: | ultramafic rocks sample digestion isotope dilution thermal ionisation mass spectrometry isotope ratios reference materials roches ultramafiques digestion d'é chantillon spectromé trie de masse à ionisation thermique et dilution isotopique rapports isotopiques maté riaux de ré fé rence |
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