Nd比值被引量：163

Precise measurement of ^(143)Nd/^(144)Nd and Sm/Nd ratios using multiple collectors inductively coupled plasma mass spectrometer (MC ICPMS)

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摘要多收集器等离子体质谱(MC-ICPMS)用于分析Sm-Nd同位素时,质量分馏系数(β)与同位素的质量数呈线性关系。可以采用两种方法进行质量分馏校正:双分馏系数内部校正法(DFIC)和单分馏系数外部校正法(SFEC)。采用DFIC法,对国际标样Shin-EtsuJNdi-1和实验室标样Nd-GIG进行了为期五个月的143Nd/144Nd比值测量统计,结果分别为0.512120±0.000012(2σSD)、0.511532±0.000013(2σSD)。采用SFEC法,对Nd-GIG标样的测量统计结果为0.511525±0.000015(2σSD)。两种方法的测量结果在分析误差范围内与其推荐值或TIMS测量值完全一致。对加Ce和Sm的Nd-GIG混合溶液分别进行了Ce和Sm对143Nd/144Nd比值分析的干扰校正研究和Sm/Nd比值测量,结果显示,143Nd/144Nd比值分别与Ce/Nd、Sm/Nd测量值呈线性关系,Sm/Nd测量值与其质量比值亦呈很好的线性关系。这表明利用MC-ICPMS可以快速精确地测定存在Ce、Sm干扰的样品的143Nd/144Nd比值,同时可获得精确的Sm/Nd比值,而无需加入稀释剂。这就使直接测定地质样品的Sm-Nd等时线年龄成为可能。 Mass fractionations in the measurement for 143Nd/144Nd and Sm/Nd isotopic ratios bya multiple collectors inductively coupled plasma mass spectrometer (MC ICPMS) are mass dependent, to which a modified exponential law and external calibration are confirmed for the calibration. Two methods are defined and applied tothe mass fractionation: (1) Double fractionation internal correction (DFIC), and (2) single fractionation external correction (SFEC). The five month measured143Nd/144Nd ratios by DFIC method for the Shin Etsu JNdi 1, and the Nd GIG, an internal laboratory neodymium isotopic reference, are 0.512 120±0.000 012 (2σSD) and ±0.000 013 (2σSD), respectively; while the 143Nd/144Nd ratios by SFEC method for the Nd GIG is ±(2σSD). These results are accordant in range of the analytical error with their recommended or TIMS measured values. Measurements of five Nd GIG solutions added cerium with Ce/Nd mass ratios from 0.05 to 1.50 reveal a negative linear correlation between the measured 140Ce/146Nd and 143Nd/144Nd ratios. While the measurements of six Nd GIG solution added samarium with Sm/Nd ratios from 0.05 to 0.70 display a positive linear correlation between the measured 147Sm/146Nd and 143Nd/144Nd ratios, the measured 147Sm/146Nd ratio also has a closely positive linear correlation with the Sm/Nd mass ratios. Consequently, the true 143Nd/144Nd ratios and Sm/Nd mass ratios can be extrapolated by substituting the variables with the measured 147Sm/146Nd or 140Ce/146Nd ratios. Our results indicate that the analytical methods are efficient to get the precise and accurate 143Nd/144Nd ratio for samples with remains of cerium and or samarium; and that they are effective to get the accurate Sm/Nd ratio for samarium nonseparated samples, without isotopic dilution. This study revealed a possible approach to directly measuring the Sm Nd isochron ages on geological samples.

作者梁细荣韦刚健李献华刘颖

机构地区中国科学院广州地球化学研究所

出处《地球化学》 CAS CSCD 北大核心 2003年第1期91-96,共6页 Geochimica

基金中国科学院知识创新工程重要方向性项目(KZCX2-102 KZXC2-101)

关键词 MC-ICPMS 多收集器等离子体质谱钐同位素钕同位素双分馏系数内部校正法单分馏系数外部校正法 MC ICPMS mass fractionation correction methods for mass bias 143Nd/144Nd isotopic ratio Sm/Nd ratio

分类号 P597 [天文地球—地球化学]

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1Halliday A N, Lee D C, Christensen J N, et al. Recent developments in inductively coupled plasma magnetic sector multiple collector mass spectrometry [J]. Intl J Mass Spectrom Ion Proc, 1995, 146/147: 21～ 33.
2Halliday A N, Lee D C, Chirstensen J N, et al. Applications of multiple collector ICPMS to cosmochemistry, geochemistry, and paleoceanography [J]. Geochim Cosmochim Acta, 1998, 62: 919～ 940.
3Walder A J, Freedman P A. Isotopic ratio measurement using a double focusing magnetic sector mass analyser with an inductively coupled plasma as an ion source [J]. J Anal At Spectrom, 1992, 7: 571～ 575.
4Walder A J, Platzner I, Freedman P A. Isotope ratio measurement of lead, neodymium and neodymium samarium mixtures, hafnium and hafnium lutetium mixtures with a double focusing multiple inductively coupled plasma mass spectrometer [J]. J Anal At Spectrom, 1993, 8: 19～ 23.
5Luais B, Telouk P, Albarede F. Precise and accurate neodymium isotopic measurements by plasma source mass spectrometry [J]. Geochim Cosmochim Acta, 1997, 61: 4 847～ 4 854.
6DePaolo D J, Wasserburg G J. Nd isotopic variations and petrogenetic models [J]. Geophys Res Lett, 1976, 3: 249～ 252.
7Wasserburg G J, Jacobsen S B, DePaolo D J, et al. Precise determination of Sm/Nd ratios, Sm and Nd isotopic abundances in standard solutions [J]. Geochim Cosmochim Acta, 1981, 45: 2 311～ 2 323.
8Tanaka T, Togashi S, Kamioka H, et al. JNdi 1: A neodymium isotopic reference in consistency with LaJolla neodymium [J]. Chem Geol, 2000, 168: 279～ 281.
9Palacz Z. Ulta high precision neodymium isotope ratio measure ments using the micromass isoprobe, the single focusing in ductively coupled plasma source mass spectrometer (ICP MS) [A]. Abstract of EUG [C]. Strasbourg (France): EUG, 2001.
10O'Nions R K, Hamilton P J, Evensen N M. Variations in 143Nd/144Nd and 87Sr/86Sr ratios in oceanic basalts [J]. Earth Planet Sci Lett, 1977, 34: 13～ 22.