In situ LuHf geochronology offers the potential for direct dating of garnet within petrographic context. However, the method requires matrix-matched standards to calibrate measured Lu/Hf ratios. In order to assess the accuracy of this calibration, as well as the reproducibility of the resulting LuHf dates, two Lu-rich (up to 1 wt% Lu) garnet samples from the Tørdal pegmatite field in southern Norway were analysed over six analytical sessions. Multi-session isochron LuHf dates of 930.3 ± 1.4 Ma (MSWD = 1.0, 164 analyses) and 930.3 ± 1.7 Ma (MSWD = 1.5; 125 analyses) were obtained, conform with previously published age constraints. The relative standard deviation of 0.1% between the analytical sessions indicates that the dates are highly reproducible. For each individual analytical session, age uncertainties of 0.3–0.6% were achieved by measuring high Lu count rates in analog detection mode. We further describe a calibration strategy that deals with LuHf datasets where Lu is measured in both pulse and analog detector mode. Given the high analytical precision and reproducibility, we suggest that the Tørdal garnets are suitable reference materials for future LA-ICP-MS/MS LuHf studies.

中文翻译：

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使用来自挪威南部 Tørdal 伟晶岩的富 Lu 石榴石测试原位 Lu[sbnd]Hf 定年的再现性

原位 LuHf 地质年代学为在岩相学背景下直接测定石榴石年代提供了可能。然而，该方法需要基体匹配标准来校准测量的 Lu/Hf 比率。为了评估该校准的准确性以及所得 LuHf 日期的再现性，对来自挪威南部 Tørdal 伟晶岩田的两个富 Lu（Lu 含量高达 1 wt%）石榴石样品进行了六次分析。获得了 930.3 ± 1.4 Ma（MSWD = 1.0，164 次分析）和 930.3 ± 1.7 Ma（MSWD = 1.5；125 次分析）的多会话等时线 LuHf 日期，符合先前发布的年龄限制。分析会话之间 0.1% 的相对标准偏差表明日期具有高度可重复性。对于每个单独的分析会话，通过在模拟检测模式下测量高 Lu 计数率，可以实现 0.3-0.6% 的年龄不确定性。我们进一步描述了一种处理 LuHf 数据集的校准策略，其中 Lu 在脉冲和模拟检测器模式下进行测量。鉴于分析精度高且重现性好，我们建议 Tørdal 石榴石是未来 LA-ICP-MS/MS LuHf 研究的合适参考材料。