Abstract Quantitative multi-element analyses of single fluid inclusions in halite and other sedimentary minerals can provide information on the origin and chemical evolution of ancient surface waters on Earth. Integrated laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and cryogenic-scanning electron microscopy-energy dispersive spectroscopy (cryo-SEM-EDS) were used here for the quantitative analysis of fluid inclusions in halite. Single phase fluid inclusions in modern and ancient halite were analyzed using a 193 nm ArF excimer laser ablation system coupled with a quadrupole mass spectrometer to test a new calibration technique using magnesium (Mg) as an internal standard. Mg concentrations obtained by cryo-SEM-EDS analyses of fluid inclusions were used to convert LA-ICP-MS concentration ratios into absolute elemental concentrations. Mg concentrations of ancient fluid inclusions from cryo-SEM-EDS analyses were reproducible to better than 5% relative standard deviation (RSD). Comparison between the chemical composition of modern Dead Sea brine measured using ICP-OES (optical emission spectroscopy) and the composition of fluid inclusions in Dead Sea halite formed from those brines, shows that fluid inclusions in halite faithfully record the chemistry of the brines from which they precipitated. Overall LA-ICP-MS analytical precision for major ions K, Ca, S in SO4 (above 50 mmol/kg H2O) is better than 10% RSD and accuracies range from 2% to 21%. Mean concentrations of Li, B, Sr, Rb and Ba agree within 7% of their expected values and are reproducible within 15%, whereas Cs concentrations above detection limit are typically reproducible to within 15 to 25% RSD. For trace elements in seawater, such as U and Mo, quantitative analyses in fluid inclusions are achieved at concentrations above 20 nmol/kg H2O. The results from this study confirm that the precision and accuracy of major and minor elemental analysis is improved with Mg as an internal standard instead of Na and Cl used in previous studies. Controlled, optimized ablation of >30 μm fluid inclusions in halite improved the accuracy and precision and reduced the overall limit of detection (LOD) by one order of magnitude compared to previous studies. Wide ranges of LODs, between 0.7 nmol/kg H2O and 10 mmol/kg H2O, reflect variations in inclusion volume and elemental concentrations. Analytical accuracies obtained for major elements demonstrate that cryo-SEM-EDS and LA-ICP-MS are complementary microbeam techniques for chemical analysis of individual fluid inclusions in halite.

中文翻译：

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LA-ICP-MS 和cryo-SEM-EDS 组合：一种改进的岩盐流体包裹体中主要、次要和微量元素定量分析技术

摘要 对岩盐和其他沉积矿物中的单一流体包裹体进行定量多元素分析可以提供有关地球上古代地表水的起源和化学演化的信息。集成激光烧蚀-电感耦合等离子体质谱 (LA-ICP-MS) 和低温扫描电子显微镜-能量色散光谱 (cryo-SEM-EDS) 用于定量分析岩盐中的流体包裹体。使用 193 nm ArF 准分子激光烧蚀系统和四极杆质谱仪分析现代和古代岩盐中的单相流体包裹体，以测试使用镁 (Mg) 作为内标的新校准技术。通过流体包裹体的低温-SEM-EDS 分析获得的 Mg 浓度用于将 LA-ICP-MS 浓度比转换为绝对元素浓度。来自低温-SEM-EDS 分析的古代流体包裹体的 Mg 浓度可重现，相对标准偏差 (RSD) 优于 5%。使用 ICP-OES（光学发射光谱法）测量的现代死海盐水的化学成分与由这些盐水形成的死海岩盐中流体包裹体的组成之间的比较表明，岩盐中的流体包裹体忠实地记录了盐水的化学成分，其中他们沉淀。SO4 中主要离子 K、Ca、S（高于 50 mmol/kg H2O）的总体 LA-ICP-MS 分析精度优于 10% RSD，准确度范围为 2% 至 21%。Li、B、Sr 的平均浓度，Rb 和 Ba 的一致性在其预期值的 7% 以内，可重现性在 15% 以内，而高于检测限的 Cs 浓度通常可重现性在 15% 至 25% RSD 以内。对于海水中的微量元素，如 U 和 Mo，可在浓度高于 20 nmol/kg H2O 时对流体包裹体进行定量分析。本研究的结果证实，使用 Mg 作为内标而不是先前研究中使用的 Na 和 Cl，提高了主要和次要元素分析的精密度和准确度。与之前的研究相比，对岩盐中 >30 μm 流体包裹体的受控、优化消融提高了准确性和精确度，并将总体检测限 (LOD) 降低了一个数量级。范围广泛的 LOD，介于 0.7 nmol/kg H2O 和 10 mmol/kg H2O 之间，反映夹杂物体积和元素浓度的变化。主要元素的分析精度表明，cryo-SEM-EDS 和 LA-ICP-MS 是互补的微束技术，可用于对岩盐中的单个流体包裹体进行化学分析。