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建立了超低本底单颗粒锆石高精度CA-ID-TIMS U-Pb分析方法.与国内早期实验室报道的全流程Pb本底(30~50 pg)相比,目前本工作全流程Pb本底水平已降低1个数量级以上(2~3 pg),可以更好地满足单颗粒锆石高精度ID-TIMS U-Pb定年要求.同时,详细研究了Pb流程本底的来源,并且对全流程Pb本底获得较高精度的Pb同位素比值测定结果.采用所建立分析流程对清湖(Qinghu),Ple?ovice,Temora 2等标准锆石进行了分析,获得了与文献报道值一致的Pb/U年龄测定结果,~(206)Pb/~(238)U加权平均值年龄测定精度优于0.25%(2σ,n≥7).
A high precision CA-ID-TIMS U-Pb analytical method for ultra-low background single grain zircon was established.Compared with the whole-process Pb background (30 ~ 50 pg) reported by early laboratory in our country, The background level has been reduced by more than one order of magnitude (2 ~ 3 pg), which can better meet the requirement of single-grain zircon ID-TIMS U-Pb dating.Meanwhile, the source of Pb process background is studied in detail, The results of the determination of Pb isotope ratios with higher accuracy were obtained in the whole process of Pb.According to the established analytical procedures, the standard zircons such as Qinghu, Pleroy and Temora 2 were analyzed and the results were consistent with those reported in the literature The results of Pb / U dating show that the accuracy of ~ (206) Pb / ~ (238) U weighted average is better than 0.25% (2σ, n≥7).