In situ U-Pb geochronology and hafnium, oxygen and zirconium isotope measurements in zircons using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and ion microprobe techniques can provide essential isotopic data to constrain geological evolutionary histories. Developing reliable zircon reference materials is the cornerstone for in situ zircon chronology and isotopic studies. In this study, the homogeneity of U-Pb ages and Hf-O-Zr isotope ratios in three Sri Lankan zircon megacrysts (SLZA, SLZB and SLZC) were investigated using multiple analytical methods. The obtained U, Th, Pb and Hf mass fractions of the SLZA zircon were 839 ± 56 μg g^-1 (1s), 151 ± 15 μg g^-1 (1s), 198 ± 28 μg g^-1 (1s) and 8635 ± 286 μg g^-1 (1s), respectively. The mass fractions of U, Th, Pb and Hf in the SLZB zircon were 1106 ± 106 μg g^-1 (1s), 331 ± 61 μg g^-1 (1s), 376 ± 57 μg g^-1 (1s) and 9673 ± 976 μg g^-1 (1s), respectively. The U, Th, Pb and Hf mass fractions determined in the SLZC zircon were 551 ± 35 μg g^-1 (1s), 111 ± 8 μg g^-1 (1s), 129 ± 18 μg g^-1 (1s) and 7881 ± 393 μg g^-1 (1s), respectively. The chemical abrasion isotope dilution thermal ionisation mass-spectrometry (CA-ID-TIMS) method yielded a Th-corrected weighted mean ²⁰⁶Pb/²³⁸U age of 556.94 ± 1.29 Ma (95% conf., n = 5) for the SLZA zircon, 552.90 ± 1.29 Ma (95% conf., n = 7) for the SLZB zircon and 560.83 ± 1.29 Ma (95% conf., n = 7) for the SLZC zircon. The obtained Hf isotopic compositions of the SLZA, SLZB and SLZC zircons determined with the solution MC-ICP-MS method were 0.281651 ± 0.000014 (2s, n = 10), 0.281704 ± 0.000008 (2s, n = 10) and 0.281676 ± 0.000006 (2s, n = 10), respectively. The obtained O isotopes of the SLZA and SLZB zircons measured with the laser fluorination method were 12.14 ± 0.56‰ (2s, n = 4) and 11.91 ± 0.30‰ (2s, n = 4), respectively. The Zr isotopes of the SLZA, SLZB and SLZC zircons determined with double spike TIMS analysis yielded mean δ⁹⁴/⁹⁰Zr_SRM3169 values of -0.03 ± 0.06‰ (2s, n = 10), -0.03 ± 0.04‰ (2s, n = 10) and 0.00 ± 0.07‰ (2s, n = 8), respectively. The SLZA zircon can be used as a primary reference or quality control material for microbeam U-Pb, Hf and Zr isotope measurements because of its slight heterogeneity. The U-Pb, Hf and Zr isotopic compositions of the SLZB and SLZC megacrysts were homogeneous. The O isotopic compositions in the SLZA and SLZB zircon were slightly dispersed, indicating that these two megacrysts can only serve as secondary reference materials for microbeam O isotope measurements.

中文翻译：

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三种斯里兰卡锆石巨晶的表征，作为微束 U-Pb 地质年代学和 Hf-O-Zr 同位素测量的潜在参考材料

使用激光烧蚀电感耦合等离子体质谱 (LA-ICP-MS) 和离子微探针技术进行原位 U-Pb 地质年代学以及锆石中铪、氧和锆同位素测量，可以提供必要的同位素数据来约束地质演化历史。开发可靠的锆石标准材料是原位锆石年代学和同位素研究的基石。在这项研究中，使用多种分析方法研究了三个斯里兰卡锆石巨晶（SLZA、SLZB 和 SLZC）中 U-Pb 年龄和 Hf-O-Zr 同位素比的均匀性。获得的SLZA锆石的U、Th、Pb和Hf质量分数分别为839±56 μg g ^-1 (1 s )、151±15 μg g ^-1 (1 s)、198 ± 28 μg g ^-1 (1 s ) 和 8635 ± 286 μg g ^-1 (1 s )。SLZB锆石中U、Th、Pb、Hf的质量分数分别为1106±106 μg g ^-1 (1 s )、331±61 μg g ^-1 (1 s )、376±57 μg g ^-1 (1 s ) ) 和 9673 ± 976 µg g ^-1 (1 s )。SLZC 锆石中测定的 U、Th、Pb 和 Hf 质量分数分别为 551 ± 35 μg g ^-1 (1 s )、111 ± 8 μg g ^-1 (1 s )、129 ± 18 μg g ^-1 (1 s) 和 7881 ± 393 μg g ^-1 (1 s )。 化学磨损同位素稀释热电离质谱 (CA-ID-TIMS) 方法得出SLZA 锆石的Th 校正加权平均²⁰⁶ Pb/ ²³⁸ U 年龄为 556.94 ± 1.29 Ma（95% conf. ，n = 5）  SLZB 锆石为552.90 ± 1.29 Ma（95% conf. ，n = 7），SLZC 锆石为 560.83 ± 1.29 Ma（95% conf. ，n  = 7）。采用溶液MC-ICP-MS法测定SLZA、SLZB和SLZC锆石的Hf同位素组成分别为0.281651±0.000014(2s, n = 10  )、0.281704±0.000008(2s , n ) = 10) 和 0.281676 ± 0.000006 (2 s , n  = 10)。采用激光氟化法测得SLZA和SLZB锆石的O同位素分别为12.14±0.56‰(2s , n =  4)和11.91±0.30‰(2s , n =  4)。通过双峰 TIMS 分析确定的 SLZA、SLZB 和 SLZC 锆石的 Zr 同位素得出的 δ ⁹⁴ / ⁹⁰ Zr _SRM3169平均值为 -0.03 ± 0.06 ‰ (2 s , n  = 10)、-0.03 ± 0.04 ‰ (2 s , n  = 10) 和 0.00 ± 0.07‰ (2 s , n = 8) 分别。由于 SLZA 锆石具有轻微的异质性，因此可用作微束 U-Pb、Hf 和 Zr 同位素测量的主要参考或质量控制材料。SLZB 和 SLZC 巨晶的 U-Pb、Hf 和 Zr 同位素组成是均匀的。SLZA和SLZB锆石中的O同位素组成略有分散，表明这两个巨晶只能作为微束O同位素测量的辅助参考材料。