High-precision Pb isotope analysis by multicollector-ICP-mass-spectrometry using Tl-205/Tl-203 normalization: Optimization and calibration of the method for the studies of Pb isotope variations

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	High-precision Pb isotope analysis by multicollector-ICP-mass-spectrometry using Tl-205/Tl-203 normalization: Optimization and calibration of the method for the studies of Pb isotope variations
	Chernyshev, I. V.
刊名	Geochemistry International
	2007
卷号	45 期号:11 页码:1065-1076
ISSN号	0016-7029
中文摘要	The development of the MC-ICP-MS method, which was launched about one decade ago and was largely stimulated by the need to solve geological problems, has opened a new avenue in isotope mass spectrometry. One of the advantages of this method is the possibility of applying a newly developed approach to the correction of analytical results for the effect of mass discrimination by normalizing the measured isotope ratios of an element to a reference (standard) isotope ratio of another element. This makes it possible to overcome the main disadvantage of conventional thermal ionization mass spectrometry (TIMS), in which the effect of mass discrimination cannot be fully taken into account during isotope analysis, and thus to implement a highly accurate method for the analysis of Pb-isotope composition. In application to the capability of the NEPTUNE MC-ICP mass spectrometer, we optimized and calibrated a method for high-accuracy Pb isotope analysis in solutions spiked with Tl, with all currently measured Pb-isotope ratios normalized to the standard Tl-205/Tl-203 ratio (TLN-MC-ICP-MS). The factors affecting the random and systematic analytical errors were examined, and the optimal operating regime and analytical conditions were determined. Much attention was paid to the correlation of the measurement results and the mass discrimination effect determined from the Tl-205/Tl-203 ratio. The value of the Tl-205/Tl-203 normalizing ratio was analytically determined through isotope analyses of the NIST SRM 981, and SRM 982 standard samples of Pb-isotope composition. The data obtained for two mixtures Tl + Pb (SRM 982) and Tl + Pb (SRM 981) in ten replicate analyses were 2.38898 +/- 12 and 2.38883 +/- 20, respectively. These results are in good mutual agreement, and their general mean Tl-205/Tl-203 = 2.3889 +/- 1 coincides (within the error) with the recently published values of 2.3887 +/- 7 [Collerson et al., 2002] and 2.3889 +/- 1 [Thirlwall, 2002]. The precision of the method (+/- 2SD), which was assayed by the long-term reproducibility of the results of replicate analyses of SRM 981 and seven galena samples (90 analyses) was 0.016-0.018% for the Pb-206/Pb-204, Pb-207/Pb-204, and Pb-208/Pb-204 ratios and 0.005 and 0.009% for the Pb-207/Pb-206 and Pb-208/Pb-206 ratios, respectively. The precision of the isotope analysis of common Pb was significantly improved (by factors of 6-10 for various isotope ratios) compared with the precision of TIMS techniques acceptable in isotope studies during three decades. The described method was applied to examine the Pb-isotope composition of approximately 250 samples of galena, scheelite, and pyrite from a number of well known (including large) gold, sulfied, and base-metal deposits. The precision of the method (0.01-0.02%) makes it possible to study small inter-and intra-phase differences in Pb-isotope ratios in hydrothermal and magmatic rocks, to assay the scale of regional and variations in the isotope composition of ore Pb, and to correlate the Pb-isotope composition of rocks and ores and reveal its evolutionary trends.
公开日期	2015-03-27
内容类型	期刊论文
源URL	[http://ir.xtbg.org.cn/handle/353005/8464]
专题	西双版纳热带植物园_公共技术服务中心主要仪器相关文献_同位素质谱仪
推荐引用方式 GB/T 7714	Chernyshev, I. V.. High-precision Pb isotope analysis by multicollector-ICP-mass-spectrometry using Tl-205/Tl-203 normalization: Optimization and calibration of the method for the studies of Pb isotope variations[J]. Geochemistry International,2007,45(11):1065-1076.
APA	Chernyshev, I. V..(2007).High-precision Pb isotope analysis by multicollector-ICP-mass-spectrometry using Tl-205/Tl-203 normalization: Optimization and calibration of the method for the studies of Pb isotope variations.Geochemistry International,45(11),1065-1076.
MLA	Chernyshev, I. V.."High-precision Pb isotope analysis by multicollector-ICP-mass-spectrometry using Tl-205/Tl-203 normalization: Optimization and calibration of the method for the studies of Pb isotope variations".Geochemistry International 45.11(2007):1065-1076.