Improvement of laser ablation in situ micro-analysis to identify diagenetic alteration and measure strontium isotope ratios in fossil human teeth
Improvement of laser ablation in situ micro-analysis to identify diagenetic alteration and measure strontium isotope ratios in fossil human teeth
复制标题
改进激光烧蚀原位微分析，以识别人类牙齿化石中的成岩蚀变并测量锶同位素比率
DOI：
10.1016/j.jas.2016.04.017
复制
发表时间：
2016
影响因子：
2.8
通讯作者：
R. Grün
中科院分区：
文献类型：
--
作者：
M. Willmes;L. Kinsley;M. Moncel;R. Armstrong;M. Aubert;S. Eggins;R. Grün
在人类牙齿化石中测量的锶同位素比率是研究过去移动模式的有力工具。为了应用这种方法，需要对样品进行可能的成岩蚀变研究，并且需要采用破坏性最小的分析技术进行同位素分析。我们测试了U，Th和Zn分布图的可用性，以确定在人类牙齿的成岩叠印区。在釉质中U浓度升高的地区直接与Sr同位素组成的成岩蚀变有关。一旦牙齿内合适的域被确定，锶同位素比可以确定与微钻孔，然后进行TIMS分析或在situLA-MC-ICP-MS。获得准确的87 Sr/86 Sr同位素比从LA-MC-ICP-MS是复杂的一个多原子化合物的质量87上的一个显着的直接干扰的潜在发生。我们发现，这种多原子化合物是存在于我们的分析设置，但Ar，而不是钙为基础的，如前所述。通过调整仪器以降低氧化物水平，可以显著降低这种干扰的影响。我们将这种改进的分析方案应用于一系列人类和动物牙齿，并将结果与使用TIMS的微钻锶同位素分析进行比较。调整减少氧化物水平允许测量准确的锶同位素比率从人类和动物的牙釉质和牙本质，即使在低锶浓度。激光消融和使用改进的分析方案的溶液分析之间的平均偏移为38 ± 394 ppm（n = 21，2σ）。因此，LA-MC-ICP-MS提供了一个强大的替代微钻TIMS的分析化石人类牙齿。这种方法可以用来解开成岩叠印从牙齿内的同位素变异性，这是由于真正的变化在87 Sr/86 Sr同位素比值相关的食物来源的变化，并通过扩展活动性。
Strontium isotope ratios measured in fossil human teeth are a powerful tool to investigate past mobility patterns. In order to apply this method, the sample needs to be investigated for possible diagenetic alteration and a least destructive analytical technique needs to be employed for the isotopic analysis. We tested the useability of U, Th, and Zn distribution maps to identify zones of diagenetic overprint in human teeth. Areas with elevated U concentrations in enamel were directly associated with diagenetic alterations in the Sr isotopic composition. Once suitable domains within the tooth are identified, strontium isotope ratios can be determined either with micro-drilling followed by TIMS analysis orin situLA-MC-ICP-MS. Obtaining accurate87Sr/86Sr isotope ratios from LA-MC-ICP-MS is complicated by the potential occurrence of a significant direct interference on mass 87 from a polyatomic compound. We found that this polyatomic compound is present in our analytical setup but is Ar rather than Ca based, as was previously suggested. The effect of this interference can be significantly reduced by tuning the instrument for reduced oxide levels. We applied this improved analytical protocol to a range of human and animal teeth and compared the results with micro-drilling strontium isotopic analysis using TIMS. Tuning for reduced oxide levels allowed the measurement of accurate strontium isotope ratios from human and animal tooth enamel and dentine, even at low Sr concentrations. The average offset between laser ablation and solution analysis using the improved analytical protocol is 38 ± 394 ppm (n = 21, 2σ). LA-MC-ICP-MS thus provides a powerful alternative to micro-drilling TIMS for the analysis of fossil human teeth. This method can be used to untangle diagenetic overprint from the intra-tooth isotopic variability, which results from genuine changes in87Sr/86Sr isotope ratios related to changes in food source, and by extension mobility.
影响因子：
3.4
作者：
Foster, GL;Vance, D
通讯作者：
Vance, D