Lead isotopes are a powerful and versatile tool to elucidate fundamental geological problems related to the formation and evolution of continental crust. K-feldspar is a popular target for Pb isotope measurement as it is prevalent in many rock types and tends to capture the initial Pb isotope composition of its parental magma. We present data for a new Pb isotope reference material: Albany K-feldspar; as well as updated data for Shap K-feldspar. Results of Pb double-spike TIMS for Albany K-feldspar are ²⁰⁶Pb/²⁰⁴Pb = 16.7872 ± 0.0062, ²⁰⁷Pb/²⁰⁴Pb = 15.5640 ± 0.0056, and ²⁰⁸Pb/²⁰⁴Pb = 36.6600 ± 0.0168 (2s). TIMS measurement results for Shap K-feldspar indicate two isotopically distinct Pb populations. LA-MC-ICP-MS, with a spatial resolution as high as 15 μm, indicates a homogeneous Pb isotopic composition in Albany K-feldspar. In accord with previous studies, our results show that scatter in the measured Pb isotope ratios, related to the low natural isotopic abundance of ²⁰⁴Pb, along with the effect of isobaric ²⁰⁴Hg-²⁰⁴Pb interference, increases at lower count rates. However, the mean Pb isotope ratios measured via LA-MC-ICP-MS using a range of spot sizes are in excellent agreement with TIMS results thus highlighting the feasibility of Pb isotope determination via LA-MC-ICP-MS to access geological information preserved in small crystals, including mineral inclusions.

中文翻译：

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奥尔巴尼钾长石：一种新型铅同位素参考材料

铅同位素是阐明与大陆地壳形成和演化相关的基本地质问题的强大且通用的工具。钾长石是铅同位素测量的热门目标，因为它在许多岩石类型中普遍存在，并且倾向于捕获其母体岩浆的初始铅同位素组成。我们提供了一种新的铅同位素参考材料的数据：奥尔巴尼钾长石；以及形状钾长石的更新数据。奥尔巴尼钾长石的 Pb 双尖峰 TIMS 结果为²⁰⁶ Pb/ ²⁰⁴ Pb = 16.7872 ± 0.0062、207 ^Pb / ²⁰⁴ Pb = 15.5640 ± 0.0056 和²⁰⁸ Pb/ ²⁰⁴ Pb = 36.6600 ± 0.0168 (2 s）。形状钾长石的 TIMS 测量结果表明有两个同位素不同的 Pb 群。LA-MC-ICP-MS 的空间分辨率高达 15 μm，表明奥尔巴尼钾长石中具有均匀的 Pb 同位素组成。根据之前的研究，我们的结果表明，测量的 Pb 同位素比值的分散与²⁰⁴ Pb 的天然同位素丰度较低以及同量异位素²⁰⁴ Hg- ^{204的影响有关。}Pb 干扰在较低计数率下增加。然而，通过 LA-MC-ICP-MS 使用一系列光斑尺寸测量的平均 Pb 同位素比与 TIMS 结果非常一致，从而突出了通过 LA-MC-ICP-MS 测定 Pb 同位素以获取保存的地质信息的可行性小晶体，包括矿物内含物。