U-Pb定年锆石标准^(176)Hf/^(177)Hf比值的多接收器电感耦合等离子体质谱测定  

High-precision Measurement of Hf Isotopic Reference Values for the U-Pb Geochronology Standard Zircons by Multi-collector Inductively Coupled Plasma-Mass Spectrometry

作　　者：祁昌实[1] 李献华[1] 梁细荣[1] 刘颖[1] 涂湘林[1] 

机构地区：[1]中国科学院广州地球化学研究所同位素年代学和地球化学重点实验室

出　　处：《质谱学报》2005年第3期149-154,共6页Journal of Chinese Mass Spectrometry Society

基　　金：中国科学院广州地球化学研究所知识创新领域前沿项目(GIGCX0306)

摘　　要：利用MicromassIsoprobe型多接收器电感耦合等离子体质谱(MCICPMS)测定UPb定年国际锆石标准91500、Temora和本实验室锆石工作标准样We1的176Hf/177Hf比值。对添加Zr的室内Hf标准溶液HfGIG的模拟实验表明:Zr/Hf≤120时,Zr对Isoprobe型MCICPMS的Hf同位素比值测定值没有明显的影响,所以锆石Hf分离纯化流程采用改进的高温高压氢氟酸溶解和其后的一个离子交换分离流程实现,整个流程Hf的回收率高于90%。176Hf/177Hf比值测定采用JMC475Hf标准溶液(176Hf/177Hf=0.282160)进行外部校正并监控仪器漂移。标准样91500、Temora和We1平均的176Hf/177Hf比值测定结果分别为(0.282310±0.000034)、(0.282706±0.000020)和(0.281534±0.000009)。上述每个结果包括至少7组独立的锆石样品的溶解、分离和测定,表明标准样91500、Temora和We1是Hf同位素组成均一的。本实验结果对于激光熔蚀多接收器电感耦合等离子体质谱(LAMCICPMS)锆石原位176Hf/177Hf比值测定校正方法的检验具有重要意义。The Hf isotope ratios were determined by a Micromass Isoprobe muhiple collector-inductively coupled plasma mass spectrometry （MC-ICP-MS） for two international zircon standards 91500 and Temora and one in-house zircon standard We-1. Zircons were digested by HF in high pressure bombs. For the reason that Zr did not change Hf isotopic ratios in the simulative experiment, Hf was separated using a modified one step ion-exchange chromatography reported by Arnard et al.. The overall recovery of Hf was better than 90%. Calibrated by an external standard solution JMC-475 Hf, ^176Hf/^177Hf ratios of these standard zircons were precisely determined. The average ^176Hf/^177Hf values of 91500 and Temora and We-1 were （0. 282 310±0. 000 034）, （0. 282 706±0. 000 020） and （0.281 534±0.000 009）, respectively. Considering that the Hf isotope results above consist of at least seven separated performances of aliquots for each zircon sample, the ^176 Hf/^177 Hf ratios of 91500, Temora and We-1 were homogeneous. These results have significant implications for testing the calibration method in zircon Hf isotopic determination by laserablation multiple collector inductively coupled plasma-mass spectrometry （LA-MC-ICP-MS）.

关 键 词：多接收器电感耦合等离子体质谱(MC—ICP—MS) 锆石标准 Hf同位素 激光熔蚀多接收器电感耦合 等离子体质谱(LA—MC—ICP—MS) 

分 类 号：O657.63[理学—分析化学] P313.3[理学—化学]