Gem quality andradite-rich garnet (IUC-1), obtained from the Miocene trachyte dome near Ankara city (Turkey), has been identified as a potential natural secondary reference material for U-Pb dating. In this study, U-Pb dating was performed in five different laboratories using isotope dilution TIMS and laser ablation ICP-MS to determine the homogeneity of euhedral garnet crystals. The U-Pb ID-TIMS data for IUC-1 yielded ²⁰⁷Pb/²³⁵U and ²⁰⁶Pb/²³⁸U ages of 20.9 ± 0.4 and 20.6 ± 0.8 Ma respectively, and these values are consistent with U-Pb LA-ICP-MS analyses, in which different garnet crystals yielded ages of 20.8 ± 0.1, 20.7 ± 0.1, 20.7 ± 0.2 and 20.2 ± 0.1 Ma. An andradite (IUC-2) from the Serçeören wollastonite skarn (Turkey) can be used as a secondary reference material provided detailed imaging of the crystals is undertaken. ID-TIMS data yielded ²⁰⁷Pb/²³⁵U and ²⁰⁶Pb/²³⁸U ages of 20.4 ± 0.4 and 20.9 ± 1.0 Ma respectively, and yielded U-Pb ages on different grains of 20.5 ± 0.1, 20.7 ± 1.0, 20.8 ± 1.7 and 20.9 ± 1.6 Ma. The assigned weighted mean age of IUC-1 (20.4 ± 0.5 Ma, 2s) is proposed as a 2023 reference value. IUC-1 garnet is expected to contribute significantly to rapidly developing garnet geochronology in the near future.

中文翻译：

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通过 TIMS 和 LA-ICP-MS 对石榴石 U-Pb 定年的一种新型天然二级参考物质

从安卡拉市（土耳其）附近的中新世粗面岩圆顶获得的宝石级富含钙铁榴石的石榴石 (IUC-1) 已被确定为 U-Pb 测年的潜在天然次要参考材料。在这项研究中，U-Pb 测年在五个不同的实验室进行，使用同位素稀释 TIMS 和激光烧蚀 ICP-MS 来确定自形石榴石晶体的均匀性。IUC-1 的 U-Pb ID-TIMS 数据产生²⁰⁷ Pb/ ²³⁵ U 和²⁰⁶ Pb/ ²³⁸U 年龄分别为 20.9 ± 0.4 和 20.6 ± 0.8 Ma，这些值与 U-Pb LA-ICP-MS 分析一致，其中不同石榴石晶体产生的年龄分别为 20.8 ± 0.1、20.7 ± 0.1、20.7 ± 0.2 和 20.2 ± 0.1 毫安。来自 Serçeören 硅灰石矽卡岩（土耳其）的钙铁矿 (IUC-2) 可用作辅助参考材料，前提是对晶体进行了详细成像。ID-TIMS 数据得到的²⁰⁷ Pb/ ²³⁵ U 和²⁰⁶ Pb/ ²³⁸ U 年龄分别为 20.4 ± 0.4 和 20.9 ± 1.0 Ma，不同晶粒上的 U-Pb 年龄分别为 20.5 ± 0.1、20.7 ± 1.0、20.8 ± 1.7 和20.9 ± 1.6 毫安。IUC-1 的指定加权平均年龄 (20.4 ± 0.5 Ma, 2 s) 被提议作为 2023 年的参考值。IUC-1 石榴石有望在不久的将来对快速发展的石榴石地质年代学做出重大贡献。