高精度质谱计在同位素地球化学的应用前景

陈福坤; 李秋立; 李潮峰; 李向辉; 王秀丽; 王芳

高精度质谱计在同位素地球化学的应用前景

中国科学院地质与地球物理研究所固体同位素地球化学实验室，北京 100029

基金项目:

国家自然科学基金项目 40372106

国家自然科学基金项目 40403008

详细信息

作者简介:
陈福坤(1964—)，男，博士，研究员，同位素地球化学专业.E-mail: fukun_chen@mail.igcas.ac.cn

中图分类号: P597
计量
- 文章访问数: 3677
- HTML全文浏览量: 117
- PDF下载量: 4
- 被引次数: 0
出版历程
- 收稿日期: 2005-07-18
- 刊出日期: 2005-11-25

Prospect of High Precision Mass Spectrometer in Isotope Geochemistry

Laboratory for Radiogenic Isotope Geochemistry, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China

摘要

摘要: 微量地质样品的高精度同位素比值测试已经成为地质和环境科学等领域极其重要的研究手段.新型固体热电离质谱计以其高精度和高灵敏度, 将在同位素年代学和地球化学领域有广阔的应用前景.报道采用IsoProbeT质谱计测量标准物质溶液的结果.测量锶标准物质NBS987和钕标准物质Ames分别获得平均⁸⁷Sr/⁸⁶Sr比值0.710 241 8±0.000 005 1和平均¹⁴³Nd/¹⁴⁴Nd比值0.512 148 4±0.000 002 9, 内部精度可达0.000 3%.微量锶标准物质(0.3~1 ng) 的同位素比值测量内部精度可以优于0.003%.结合低本底化学流程, 实现了微量地质样品的高精度同位素比值测试.这一结合将有效地促进单颗粒矿物年代学和同位素示踪在岩浆岩、变质岩、矿床、构造岩研究的应用.
- 质谱计 /
- 高精度 /
- 低本底 /
- 年代学 /
- 同位素地球化学
Abstract: The high precision measurement of isotopic ratios for micro-geological samples has become very important in the geological and environmental sciences. Recently developed solid-source thermal ionization mass spectrometers are highly precise and sensitive, and are playing a crucial role in isotopic geochronology and geochemistry. This paper reports analytical data obtained from standard material solutions using an IsoProbe-T mass spectrometer. Measurements on the Sr standard material NBS987 and Nd standard material Ames yielded mean ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd ratio values of 0.710 241 8± 0.000 005 1 and 0.512 148 4±0.000 002 9, respectively, with an internal precision better than 0.000 3%. Measurements using a small amount of the Sr standard material solution NBS987 (0.3-1 ng) yielded an internal precision significantly better than 0.003%. Combining chemical separation procedures having low blank, measurements of micro-geological samples have successively been achieved. This combination of low-blank chemical procedures and the use of a high precision mass spectrometer will potently promote applications of single-grain geochronology and isotopic tracer on magmatic rocks, metamorphic rocks, ore deposits and tectonites.
- mass spectrometer /
- high precision /
- low blank /
- geochronology /
- isotope geochemistry

HTML全文

图 1 IsoProbe-T质谱计17个接收器分布

Fig. 1. Array of seventeen receivers of the IsoProbe-T mass spectrometer

下载: 全尺寸图片幻灯片

图 2 Sr和Nd标准物质溶液的测量结果(NBS987和Ames)

Fig. 2. Analytical data of Sr and Nd standard material solutions

下载: 全尺寸图片幻灯片

图 3 锆石Pb-Pb蒸发法分析结果

a.锆石颗粒1测量过程中²⁰⁶Pb信号强度变化; b.锆石颗粒1测得的²⁰⁷Pb/²⁰⁶Pb比值; c.锆石颗粒1测得的²⁰⁸Pb/²⁰⁶Pb比值变化; d.锆石颗粒2测得的²⁰⁷Pb/²⁰⁶Pb比值变化, 指示核边结构或复杂的锆石结晶历史

Fig. 3. Analytical data using the zircon Pb-Pb evaporation method

下载: 全尺寸图片幻灯片

图 4 低本底高温高压蒸汽法溶样

Fig. 4. Low-blank vapor digestion method under high-temperature and high-pressure conditions

下载: 全尺寸图片幻灯片

图 5 微量Sr标准物质溶液NBS987同位素比值测量结果

Fig. 5. Analytical data using a small amount of the Sr standard material solution NBS987

下载: 全尺寸图片幻灯片

表 1 标准物质溶液NBS987 Sr测量结果

Table 1. Analytical data of the Sr standard material solution NBS987

表 2 标准物质溶液Ames Nd测量结果

Table 2. Analytical data of the Nd standard material solution Ames

参考文献(25)

[1]	Chen, F., Hegner, E., Todt, W., 2000. Zircon ages, Nd isotopic and chemical compositions of orthogneisses from the Black Forest, Germany—Evidence for a Cambrian magmatic arc. Int. J. Earth Sci. , 88: 791-802. doi: 10.1007/s005310050306
[2]	Cherniak, D. J., Watson, E. B., 2000. Pb diffusion in zircon. Chem. Geol. , 172: 5-24.
[3]	Cocherie, A., Guerrot, C., Rossi, P., 1992. Single-zircon dating by step-wise Pb evaporation: Comparison with other geochronological techniques applied to the Hercynian granites of Corsica, France. Chem. Geol. , 101: 131-141.
[4]	Gagnevin, D., Daly, J. S., Poli, G., et al., 2005a. Microchemical and Sr isotopic investigation of zoned K-feldspar megacrysts: Insights into the petrogenesis of a granitic system and disequilibrium crystal growth. J. Petrol. , 46: 1689-1724. doi: 10.1093/petrology/egi031
[5]	Gagnevin, D., Daly, J. S., Waight, T. E., et al., 2005b. Pb isotopic zoning of K-feldspar megacrysts determined by laser ablation multi-collecter ICP-MS: Insights into granite petrogenesis. Geochim. Cosmochim. Acta, 69: 1899-1915. doi: 10.1016/j.gca.2004.10.007
[6]	Harper, Jr. C. L., Jacobsen, S. B., 1992. Evidence from coupled ¹⁴⁷Sm-143Nd and ¹⁴⁶Sm-¹⁴²Nd systematics for very early (4.5-Gyr) differentiation of the earth's mantle. Nature, 360: 728-732. doi: 10.1038/360728a0
[7]	Jacobsen, S. B., Wasserburg, G. J., 1984. Sm-Nd isotopic evolution of chondrites and achondrites, Ⅱ. Earth Planet. Sci. Lett. , 67: 137-150. doi: 10.1016/0012-821X(84)90109-2
[8]	Klötzli, U. S., 1997. Single zircon evaporation thermal ionisation mass spectrometry: Method and procedures. Analyst, 122: 1239-1248. doi: 10.1039/a704114d
[9]	Kober, B., 1986. Whole-grain evaporation for²⁰⁷Pb/²⁰⁶Pb age—Investigations on single zircons using a doublefilament thermal ion source. Contrib. Mineral. Petrol. , 93: 482-490. doi: 10.1007/BF00371718
[10]	Kober, B., 1987. Single zircon evaporation combined with Pb⁺ emitter bedding for ²⁰⁷Pb/²⁰⁶Pb-age investigations using thermal ion mass spectrometry, and implications to zirconology. Contrib. Mineral. Petrol. , 96: 63-71. doi: 10.1007/BF00375526
[11]	Krogh, T. E., 1982. Improved accuracy of U-Pb zircon ages by the creation of more concordant systems using air abrasion technique. Geochim. Cosmochim. Acta, 46, 637-649. doi: 10.1016/0016-7037(82)90165-X
[12]	Lee, J. K. W., Williams, I. S., Ellis, D. J., 1997. Pb, U and Th diffusion in natural zircon. Nature, 390: 159-161. doi: 10.1038/36554
[13]	Lesher, C. E., 1994. Kinetics of Sr and Nd exchange in silicate liquids: Theory, experiments, and applications to uphill diffusion, isotopic equilibration, and irreversible mixing of magmas. J. Geophys. Res. , 99: 9585-9604. doi: 10.1029/94JB00469
[14]	Li, Q. L., Chen, F. K., Wang, X. L., et al., 2005. Low-blank chemical separation procedure and the single grain mica Rb-Sr isochron dating method. Chinese Sci. Bull. (inpress).
[15]	Li, S. G., Jagoutz, E., Chen, Y. Z., et al., 2000. Sm-Nd and Rb-Sr isotopic chronology and cooling history of ultra-high pressure metamorphic rocks and their country rocks at Shuanghe in the Dabie Mountains, central China. Geochim. Cosmochim. Acta, 64: 1077-1093. doi: 10.1016/S0016-7037(99)00319-1
[16]	Ludwig, K. R., 2001. Isoplot/Ex, rev. 2.49: A geochronological Toolkit for Microsoft Excel. Berkeley Geochronological Center, Special Publication, (1): 58.
[17]	Mattinson, J. M., 1994. A study of complex discordance in zircons using step-wise dissolution techniques. Contrib. Mineral. Petrol. , 116: 117-129. doi: 10.1007/BF00310694
[18]	Mezger, K., Krogstad, E. J., 1997. Interpretation of discordant U-Pb zircon ages: An evaluation. J. Metamorph. Geol. , 15: 127-140. doi: 10.1111/j.1525-1314.1997.00008.x
[19]	Müller, W., Mancktelow, N. S., Meier, M., 2000. Rb-Sr microchrons of synkinematic mica in mylonites: An example from the DAV fault of the Eastern Alps. Earth Planet. Sci. Lett. , 180: 385-397. doi: 10.1016/S0012-821X(00)00167-9
[20]	Müller, W., 2003. Strengthening the link between geochronology, textures and petrology. Earth Planet. Sci. Lett. , 206: 237-251. doi: 10.1016/S0012-821X(02)01007-5
[21]	Poller, U., Liebetrau, V., Todt, W., 1997. U-Pb singlezircon dating under cathodoluminescence control (CLC-method): Application to polymetamorphic orthogneisses. Chem. Geol. , 139: 287-297. doi: 10.1016/S0009-2541(97)00040-5
[22]	Sergeev, S. A., Komarov, A. N., Bickel, R. A., et al., 1997. A new microtome for cutting hard submillimeter-sized crystalline objects for promoting high-resolution instrumental microanalysis. Eur. J. Mineral. , 9: 449-456. doi: 10.1127/ejm/9/2/0449
[23]	Sharma, M., Papanastassiou, D. A., Wasserburg, G. J., et al., 1996. The issue of the terrestrial record of 146Sm. Geochim. Cosmochim. Acta, 60: 2037-2047. doi: 10.1016/0016-7037(96)00082-8
[24]	Waight, T. E., Maas, R., Nicholls, I. A., 2000. Fingerprinting feldspar phenocrysts using crystal isotopic composition stratigraphy: Implications for crystal transfer and magma mingling in S-type granites. Contrib. Mineral. Petrol. , 139: 227-239. doi: 10.1007/s004100000128
[25]	Wieser, M. E., Schwieters, J. B., 2005. The development of multiple collector mass spectrometry for isotope ratio measurement. Int. J. Mass Spectrometry, 242: 97-115. doi: 10.1016/j.ijms.2004.11.029