The use of LA-ICP-MS for uranium determination in the fission track dating technique is becoming increasingly popular because of several advantages over the classical external detector method and a variety of analytical and statistical protocols have been developed. However, two important issues remain unresolved in the context of the LA-ICP-MS approach (i) how to best deal with low track density (ρ_s) samples, and (ii) does a correlation between age and uranium content (or eU) reflect an annealing dependence or not? To assess the impact of the analytical methodology on these issues, we compare the multi-spot and more classical single spot methods on samples of known ages, variably zoned and/or with low track densities. To make the comparison we use an approach, implemented in a Python script, that randomly samples our multi-spot ICP-MS data to choose a single U measurement per grain, simulating the single spot approach. We then calculate the central age, p(χ²) and dispersion of the simulated single spot analysis and repeat this 2000 times. Our results show that the multi-spot approach is robust for low ρ_s and zoned samples, yielding both accurate and precise results without over-dispersion. Additionally, our random sampling approach shows that a single spot measurement can induce an overdispersion coupled to a relationship between single grain age and U content. This is at least partly attributable to zonation that creates a mismatch between the U in the counted area and the spot-measured U. Therefore, we recommend that if over-dispersion is observed for basement samples, when one typically expects a single age population, then multiple spot analysis should be carried out to assess if the excess dispersion is linked to undetected zoning and/or laser spot misplacement rather than to U dependent annealing behaviour.

在裂变径迹测年技术中，使用LA-ICP-MS进行铀测定变得越来越普遍，这是因为它具有优于经典外部探测器方法的多种优势，并且已经开发了多种分析和统计方案。但是，有两个重要的问题在LA-ICP-MS方法的情况下仍然没有得到解决（我）如何与低磁道密度最划算（ρ_小号）样品，以及（ii）年龄与铀含量（或eU）之间的相关性是否反映出退火依赖性？为了评估分析方法对这些问题的影响，我们比较了多点法和更经典的单点法对已知年龄，可变区域和/或低径迹密度的样本的影响。为了进行比较，我们使用一种在Python脚本中实现的方法，该方法随机采样我们的多点ICP-MS数据，以模拟单个点的方法，对每个谷物选择一个U量度。然后，我们计算出中央年龄，P（χ ²）和分散的模拟单点分析和重复这个2000倍。我们的结果表明，多点方法对于低ρs是鲁棒_的和分区的样品，可以得到准确而精确的结果，而不会过度分散。此外，我们的随机抽样方法表明，单点测量可能会导致过度分散，这与单晶粒龄和U含量之间的关系有关。这至少部分归因于分区，该分区在计数区域的U与现场测量的U之间造成了不匹配。因此，我们建议，如果在地下室样本中观察到过度分散的情况，那么通常会期望一个年龄段的人口，然后应进行多点分析，以评估过量的色散是否与未检测到的分区和/或激光点错放有关，而不是与U依赖的退火行为有关。