Metrology and traceability of U-Pb isotope dilution geochronology (EARTHTIME Tracer Calibration Part I)
Metrology and traceability of U-Pb isotope dilution geochronology (EARTHTIME Tracer Calibration Part I)
复制标题
DOI：
10.1016/j.gca.2015.05.026
复制
发表时间：
2015-09-01
影响因子：
5
通讯作者：
Parrish, R. R.
中科院分区：
文献类型：
--
作者：
Condon, D. J.;Schoene, B.;Parrish, R. R.
在EARTHTIME计划的主持下，制备了用于U-Pb同位素稀释同位素比质谱法的U-235-U-233-Pb-205（-Pb-202）混合示踪剂。文中给出了铀铅比和同位素丰度的制备和标定方法及结果，并对各种不确定度来源进行了讨论和量化。EARTHTIME U-Pb示踪剂同位素组成的准确度可以通过一系列测定和同位素组成参考材料与本文所述的实验相结合追溯到SI单位。用于计算U/Pb比值（和间接U-Pb测年）的参数具有相关的不确定性，导致Pb-206/U-238测年的总不确定性贡献为+/- < 0.03%（95%置信度）。对于合适的陆地材料，如锆石，当其他不确定性来源已被最小化时（例如，开放系统行为、U-238/U-235变异、中间子体产物不平衡、常见铅等）U-Pb示踪剂刻度的不确定性是U-Pb年代学准确性的一个限制因素，但比U-238和U-235衰变常数的不确定性（+/- 0.11和0.14%2 σ）要小。混合EARTHTIME U-235-U-233-Pb-205（-Pb-202）示踪剂的校准方法，以及参考物质的更新值（例如，混合重量分析参考溶液），和参数（例如，铅标准物质测定），可应用于其他实验室特定的铀铅示踪剂，并将有助于生成准确和直接相互可比的铀铅数据。(C)2015作者爱思唯尔有限公司出版
Mixed U-235-U-233-Pb-205(-Pb-202) tracers for U-Pb isotope-dilution isotope ratio mass spectrometry have been prepared under the auspices of the EARTHTIME Initiative. The methods and results for the preparation and calibration of the U/Pb ratio and isotopic abundances are given, and the various sources of uncertainty are discussed and quantified. The accuracy of the EARTHTIME U-Pb tracer isotopic composition can be traced back to SI units via a series of assay and isotopic composition reference materials combined with the experiments described herein. The parameters used in calculating U/Pb ratios (and inferentially U-Pb dates) have correlated uncertainties that result in a total uncertainty contribution to Pb-206/U-238 dates of +/- < 0.03% (95% confidence). For suitable terrestrial materials such as zircon, when other sources of uncertainty have been minimised (e.g., open-system behaviour, U-238/U-235 variation, intermediate daughter product disequilibrium, common Pb, etc.) the U-Pb tracer calibration uncertainty is a limiting factor in the accuracy of U-Pb geochronology - but less so than the uncertainty in the U-238 and U-235 decay constants (+/- 0.11 and 0.14% 2 sigma). The calibration approach of the mixed EARTHTIME U-235-U-233-Pb-205(-Pb-202) tracers, in addition to updated values for reference materials (e.g., mixed gravimetric reference solutions), and parameters (e.g., Pb reference material assay), can be applied to other laboratory-specific U-Pb tracers and will facilitate the generation of accurate and directly inter-comparable U-Pb data. (C) 2015 The Authors. Published by Elsevier Ltd.