Simultaneous in situ determination of Pb isotope ratios and trace element concentrations in melt inclusions by LASS-ICP-MS
Simultaneous in situ determination of Pb isotope ratios and trace element concentrations in melt inclusions by LASS-ICP-MS
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LASS-ICP-MS 同时原位测定熔体包裹体中的 Pb 同位素比和微量元素浓度
DOI：
10.1029/2020gc009451
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Zhong-Yuan Ren
中科院分区：
文献类型：
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作者：
Le Zhang;Sheng-Ping Qian;Nan Li;Lu-Bing Hong;Yan-Qiang Zhang;Zhong-Yuan Ren
熔体包裹体为岩浆来源和过程提供了独特的见解。采用193 nm准分子激光烧蚀系统，结合多接收电感耦合等离子体质谱仪（MC-ICP-MS）和扇形场ICP-MS（SF-ICP-MS），对熔融包裹体中Pb同位素和微量元素进行了同时测定。用Y形连接器将烧蚀的气溶胶分成两股气流，同时输送到两个质谱仪中。在MC-ICP-MS上测量铅同位素，而在SF-ICP-MS上测定微量元素浓度。当气溶胶被分成可变比例（5：5，6：4，7：3，8：2-9：1）时，观察到的分析偏倚很小。通过对5块地质标准玻璃的两种激光光斑直径（33 μ m和45 μm）的分析，评价了该方法的精密度和准确度。33种微量元素的测定值均与参考值（±10%）一致，精密度均小于15%（2 RSD）。208 Pb/206 Pb和207 Pb/206 Pb比值的精度与Pb浓度相关。从BHVO-2G（Pb = 1.6 ppm）到TB-1G（Pb = 16.1 ppm），在33 μm激光光斑直径下，这些比值的精度从约0.4%提高到0.2%。五种参考玻璃的平均Pb同位素比值在参考值的0.15%以内。利用我们的新方法，铅同位素比值和微量元素含量的斜长石托管熔融包裹体在大洋中脊玄武岩从印度洋测量。
Melt inclusions provide unique insights into magmatic sources and processes. This study presents a method for simultaneously measuring Pb isotopes and trace elements in melt inclusions using a 193 nm excimer laser ablation system coupled to a multiple‐collector inductively coupled plasma‐mass spectrometer (MC‐ICP‐MS) and a sector‐field ICP‐MS (SF‐ICP‐MS). The ablated aerosol was split with a Y‐shaped connector into two gas streams, which were simultaneously transported into two mass spectrometers. Lead isotopes were measured on the MC‐ICP‐MS, while trace element concentrations were determined on the SF‐ICP‐MS. Little analytical bias was observed when the aerosol is divided into variable proportions (5:5, 6:4, 7:3, 8:2–9:1) to the two instruments. The precision and accuracy of this method were evaluated by analyzing five geological reference glasses with two laser spot diameters (33, and 45 μm). All the 33 measured trace element concentrations are consistent with the reference values (±10%) and have precisions less than 15% (2RSD). The precisions of the 208Pb/206Pb, and 207Pb/206Pb ratios correlate with Pb concentrations. From BHVO‐2G (Pb = 1.6 ppm) to TB‐1G (Pb = 16.1 ppm), the precision on these ratios improve from about 0.4%–0.2% with a 33 μm laser spot diameter. The mean Pb isotope ratios for the five reference glasses are within 0.15% of the reference values. Using our new method, Pb isotope ratios and trace element contents of plagioclase‐hosted melt inclusions in a mid‐ocean ridge basalt from the Indian Ocean were measured.