【作者】 陈开运；

【导师】 袁洪林；

【作者基本信息】 西北大学 ， 地球化学， 2013， 博士

【摘要】 本文对溶液和飞秒激光剥蚀进样多接收电感耦合等离子质谱(SN/fLA-MC-ICP-MS)同位素分析测试及其在地质科学中的应用进行了探讨。主要开展以下几个方面的研究：以氮气(N2)为例,较深入地探讨了辅助气体在MC-ICP-MS同位素分析测试中的增敏机理：通过实验人工合成锆石Lu-Hf同位素外部参考物质,优化同位素分馏和干扰的校正参数及程序,从而提高了锆石Lu-Hf同位素原位微区分析的准确度和精密度：通过实验建立了地质样品中Fe同位素的分离和纯化程序及溶液雾化进样(SN)和膜去溶雾化进样(DSN)-多接收电感耦合等离子质谱(SN/DSN-MC-ICP-MS)分析方法,并用于地质样品中的Fe同位素分析测试；利用266nm飞秒激光剥蚀系统联合多接收电感耦合等离子质谱(fLA-MC-ICP-MS)探索了地质样品中Fe同位素原位微区分析的仪器参数和实验条件,建立了Fe同位素fLA-MC-ICP-MS原位分析技术和实验方法；利用266nm飞秒激光剥蚀-多接收电感耦合等离子质谱(fLA-MC-ICP-MS)分析技术进行了Pb同位素原位微区分析的仪器条件和方法研究,建立了Pb同位素fLA-MC-ICP-MS分析技术方法,并开展了部分国际标准参考物质NIST、USGS、MPI-Ding和CGSG系列参考物质中Pb同位素组成及其均一性研究工作；在实验方法研究的基础上利用266nm飞秒激光剥蚀-多接收电感祸合等离子质谱(fLA-MC-ICP-MS)分析技术对松树沟秦岭岩群斜长角闪岩进行了Pb同位素的原位微区分析,对松树沟橄榄岩中橄榄石和辉石进行了Fe同位素的原位微区分析和研究。1.以N2气为例,较深入地探讨了辅助气体在MC-ICP-MS同位素分析测试中的增敏机理。氮气的加入可以有效提高元素的离子信号强度,大多数同位素的增敏系数为0.2-0.7。在Sr-Nd-Hf-Pb同位素MC-ICP-MS分析测试过程中,N2气的加入可有效提高离子信号灵敏度,同时降低了同位素的质量歧视效应。Sr-Nd-Hf-Pb同位素分析中,Sr同位素质量数最小,N2的增敏效应最强,信号强度可提高60%,质量歧视和分馏系数下降了6%；而Pb同位素质量数最大,增敏效应最弱,信号强度仅提高了不到10%,质量歧视和分馏系数下降了9%；Nd同位素质量数中等,加入N2后信号灵敏度提高了28%,质量歧视和分馏系数下降了6%。元素(或同位素)的离子信号强度的增敏或抑制依赖于仪器的操作条件和N2气的浓度(气流量),N2气对同位素离子信号的增强效应与同位素(离子)的质量数和电离能有关,一般同位素的质量数越小,电离能越大,其增敏效应则越强,反之增敏效应越弱。2.通过实验人工合成锆石Lu-Hf同位素外部参考物质,优化了同位素分馏和干扰的校正参数及程序,从而提高了锆石Lu-Hf同位素原位分析的准确度和精密度。本文研究了人工合成锆石并加入微量元素的实验方法和条件,并准确测定了合成锆石中元素含量和Lu-Hf同位素组成。利用氧化锆和硅酸锂为原料,以氧化钼和钼酸锂为助熔剂,并加入Hf, Lu、Yb、U、Th和Pb等元素,在马弗炉中950℃保温72小时结晶生长锆石。合成的锆石晶体呈四方双锥状晶型,激光拉曼光谱分析发现其有与锆石标型矿物晶体完全一致的激光拉曼谱图。利用LA-ICP-MS和LA-MC-ICP-MS分别对锆石中微量元素和Lu-Hf同位素进行的分析测试结果表明Lu、Hf和Yb元素含量在不同颗粒之间及同一颗粒内部比较均一；而U、Th、Pb及其他元素含量在不同颗粒之间及同一颗粒内部都有较大变化；Lu-Hf同位素组成在不同颗粒之间和同一颗粒内部无变化,同一组合成锆石中176Hf/177Hf匕值在2s不确定度内完全一致,不同批次合成的锆石中尽管Yb含量不同(I76Yb/177Hf=0.000006-0.14),但176Hf/177Hf比值在2s不确定度内完全一致。本实验合成的锆石有望作为新的锆石Lu-Hf同位素外部参考物质,以用于天然锆石中Lu-Hf同位素组成分析测试的外部参考标样。3.利用266nm飞秒激光剥蚀-多接收电感耦合等离子质谱(fLA-MC-ICP-MS)技术进行了Pb同位素的原位微区分析仪器参数和实验条件研究,建立了Pb同位素的fLA-MC-ICP-MS原位微区分析方法,并开展了部分NIST、USGS、MPI-Ding和CGSG系列参考物质中Pb同位素组成及其均一性测试研究,在此基础上以松树沟秦岭岩群斜长角闪岩为例探索了Pb同位素原位微区分析在地质中应用。首先开展了以铜为基体的铜矿(如黄铜矿、辉铜矿、斑铜矿等)和金属铜(如黄铜、青铜等)Pb同位素参考物质的研究工作。对15个铜国家标准物质的测试结果表明CuPb12(GBW02137)中Pb同位素组成均一,Pb同位素比值外部精度RSD均小于90ppm,可作为以Cu为基体的金属铜及铜矿等样品中Pb同位素原位微区分析的实验室外部参考物质。本文还探索了Pb/T1摩尔比、激光能量、剥蚀频率、载气和激光剥蚀系统(准分子纳秒激光和飞秒激光)以及质量歧视校正策略对Pb同位素分析结果的影响,研究结果表明,Pb/TI摩尔比1.8-5.3可获得高精确度的Pb同位素数据,是最佳比例；激光能量和剥蚀频率主要影响Pb、T1离子信号强度,对Pb、T1质量分馏系数无较大影响；载气(He和Ar气)对Pb、Tl离子信号强度和质量分馏系数都有较大影响,He气作为载气可提高信号灵敏度,降低质量歧视和分馏效应；266nm飞秒激光剥蚀相对于193rnm准分子激光质量分馏效应显著降低,由飞秒激光剥蚀诱导的分馏效应可忽略不计；依据指数定律以T1的分馏因子来校正Pb的质量歧视和分馏(考虑T1和Pb的质量分馏差异,NIST SRM997Tl同位素比值采用优化值2.38890)可获得准确的Pb同位素比值。利用fLA-MC-ICP-MS对NIST参考物质SRM610、612、614, USGS参考物质BCR-2G、 BHVO-2G、 BIR-1G和GSD-1G,以及MPI-DING参考物质Tl-G、KL-G、 GOR132-G、StHs60/80-G、 ATHO-G和ML3B-G这13个国际参考物质中Pb同位素组成进行了分析测定,分析结果与参考值或文献报道值在2s不确定度内基本一致,即使在Pb元素含量很低(～21μg·g-1)的情况下,分析结果的准确度208pb/204pb优于0.1%,207pb/206pb优于0.05%,而精密度优于分别优于0.01%和0.001%。同时,本文还首次报道了USGS(GSE-1G, GSC-1G和GSA-1G)和CGSG(CGSG-1、 CGSG-2、CGSG-4和CGSG-5)系列参考物质中Pb同位素fLA-MC-ICP-MS分析数据,研究结果表明GSE-1G、GSC-1G、GSA-1G、CGSG-1、CGSG-2、CGSG-4和CGSG-5中Pb同位素在100～200微米范围内是均一的。利用266nm飞秒激光剥蚀-多接收电感耦合等离子质谱(fLA-MC-ICP-MS)分析技术对松树沟秦岭岩群斜长角闪岩进行了Pb同位素的原位微区分析,获得了1.00±0.17Ga的Pb-Pb等时线年龄,表明松树沟秦岭岩群斜长角闪岩变质形成年龄为1.00±0.17Ga,与前人的研究结果相吻合。4.通过实验建立了Fe同位素的分离和纯化程序,开展了溶液进样(SN)及膜去溶进样(DSN)-多接收电感耦合等离子质谱分析(SN/DSN-MC-ICP-MS) Fe同位素分析的仪器参数和实验方法研究,并进行了地质样品的Fe同位素分析测试；利用266nm飞秒激光剥蚀-多接收电感耦合等离子质谱联用分析技术(fLA-MC-ICP-MS)探索了地质样品中Fe同位素原位微区分析的实验条件,并初步建立了Fe同位素的fLA-MC-ICP-MS分析技术方法；利用建立的fLA-MC-ICP-MS分析技术对松树沟地区橄榄岩中Fe同位素组成进行了分析测试。首先通过实验建立Fe同位素的分离和纯化程序,AG MP-1M阴离子交换树脂可用于地质样品中Fe同位素的分离和纯化,回收率达99%以上,同时还可用于Cu、Zn和Co的分离提纯。开展了溶液进样(SN)及膜去溶进样(DSN)-多接收电感耦合等离子质谱分析(SN/DSN-MC-ICP-MS) Fe同位素分析的仪器参数和实验方法研究,较深入探讨了MC-ICP-MS分析中ICP参数(RF功率、雾化气流量)、进样方式、分辨率及分析模式对Fe同位素分析测试的影响,获得的IRMM-014中Fe同位素δ556Fe和δ57Fe分别为-0.006%o±0.012‰(2SD)和0.002‰±0.022‰(2SD),与前人的研究结果在2s不确定范围内的完全一致。获得的δ56Fe长期外部精度为0.02‰(2SD)。同时探索了微量He气的加入对Fe同位素分析测试的影响,研究结果表明He气的加入可以提高Fe同位素的分析精度。。利用建立的SN-MC-ICP-MS分析方法进行了地质样品的Fe同位素分析测试。利用266nm飞秒激光剥蚀与多接收电感耦合等离子质谱联用分析技术(fLA-MC-ICP-MS)探索了地质样品中Fe同位素原位微区分析的实验条件,探讨了激光能量(或能量密度)、剥蚀频率和激光剥蚀斑束对Fe同位素原位微区分析结果的影响,初步建立了Fe同位素的fLA-MC-ICP-MS分析技术方法,获得的IRMM-014中Fe同位素856Fe=-0.001±0.011‰(2sd, n=52)和857Fe=-0.004±0.019‰(2sd, n=52),与前人的研究结果在2s不确定范围内完全一致,获得的δ56Fe长期外部精度为0.02%o(2SD)。以松树沟地区纯橄岩为例,利用fLA-MC-ICP-MS分析技术对纯橄岩中橄榄石和辉石中Fe同位素组成进行了分析测试和研究。更多还原

【Abstract】 In this paper, we study the solution nebulizer and femtosecond laser ablation-multicollector inductively coupled plasma mass spectrometry (SN/fLA-MC-ICP-MS) and the application in geological science. Mainly in the following aspects:The experimental synthetic zircon Lu-Hf isotope reference material, to improve mass bias and isotope fractionation and interference correction parameters and procedures, so as to improve the accuracy and precision for zircon Lu-Hf isotope in-situ analysis; established Fe isotope separation and purification of the sample program by experiment, solution nebulizer (SN) and membrane desolvation solution nebulizer (DSN)-multicollector inductively coupled plasma mass spectrometry (SN/DSN-MC-ICP-MS) for Fe isotope analysis method have been explored by instrumental parameters and analytical method;266nm femtosecond laser ablation system coupled with multicollector ICP-MS (fLA-MC-ICP-MS) to explore laser ablation conditions and instrumental parameters for in situ microanalysis of Fe isotopes in geological samples, to establish fLA-MC-ICP-MS Fe isotope in situ analysis method;266nm femtosecond laser ablation-multicollector ICP-MS (fLA-MC-ICP-MS) was also used for study instrumental parameters and analysis conditions for Pb isotope in situ analysis, and established Pb isotopic fLA-MC-ICP-MS analysis method, and to carry out a part of NIST, USGS, MPI-Ding CGSG series of reference materials (or reference glasses) Pb isotopic composition and its homogeneity research work. On the basis of the methods research266nm femtosecond laser ablation-multicollector inductively coupled plasma mass spectrometry (fLA-MC-ICP-MS) was used for in situ micro analysis Pb isotope in Songshugou Qinling Group amphibolite rock; Fe isotope in olivine and pyroxene from Songshugou peridotite was also determined by in situ microanalysis and research.I. Nitrogen gas, for example, a thorough research works to explore the effection and mechanism of auxiliary gas in MC-ICP-MS isotope analysis.During MC-ICP-MS isotope analysis, Sr-Nd-Hf-Pb isotopic analysis for example, the addition of nitrogen gas can effectively improve the ion signal intensity (increased sensitivity), while reducing the effect of isotope mass discrimination (mass bias). Sensitization or inhibition of the ion signals intensity of the elements (or isotopes) dependent on the instrument’s operating conditions and the concentration of nitrogen gas (or gas flow rate). During Sr-Nd-Hf-Pb isotopic analysis small volume of nitrogen was added, Sr isotope mass number is the smallest, but the most sensitizing effect, the signal intensity can be increased to60%with the mass fractionation coefficient decreased by6%; Pb isotopic mass sensitizing effect weak signal intensity is only increased by less than10%and the mass fractionation coefficient decreased by9%; Nd isotope mass is medium, the signal sensitivity increased28%after the addition of nitrogen gas, while mass fractionation coefficient decreased by6%. Isotope ions after nitrogen gas on the mass number and the ionization energy of the signal enhancement effect with isotope (ion). The smaller the mass number and the greater the ionization energy, the stronger it’s sensitizing effect, contrary sensitizing effect is weaker.2. Experimental synthetic zircon Lu-Hf isotope reference material, to improve isotope fractionation and interference correction parameters and procedures, thereby improving the accuracy and precision for zircon Lu-Hf isotope in situ analysis.In this paper, a synthetic zircon and experimental methods and conditions of the add trace elements, and accurate determination of element content and Lu-Hf isotope composition in synthetic zircon. The use of zirconium oxide and lithium silicate as flux raw materials, molybdenum oxide, and lithium molybdate, and add elements of Hf, Lu, Yb, U, Th, Pb, etc., after mixing into a covered platinum crucible, muffle furnace950℃for72hours for the zircon crystal growth. Synthetic zircon crystals have a perfect tetragonal crystal form of the double cone, the laser Raman spectroscopy exactly the same as that of the zircon typomorphic mineral crystal. Trace elements concentrations and zircon Lu-Hf isotope ratios were determined by the LA-ICP-MS and LA-MC-ICP-MS analysis method respectively, the test results shown that the content of Lu, Hf and Yb elements between different particles and the same particle have smaller internal changes, relatively homogeneous; U, Th, Pb, and other elements of content between different particles within the same particles have a greater change; there are no difference for Lu-Hf isotopic composition between different and the same particles or in the interior of one particle,176Hf/177Hf ratios in the same batch of synthetic zircon are in good agreement with each other in2s uncertainties. The experimental synthesis of zircon is expected as the the new zircon Lu-Hf isotope reference materials for accurate determination of Lu-Hf isotope composition in natural zircons.3. Using266nm femtosecond laser ablation-multicollector inductively coupled plasma mass spectrometry (fLA-MC-ICP-MS) analysis techniques for Pb isotopic in situ microanalysis, instrument parameters and experimental conditions have been studied for the establishment of the Pb isotopic fLA-MC-ICP-MS in situ microanalysis, and carry out a part of NIST, USGS, MPI-Ding and CGSG series of reference materials (or reference glasses) Pb isotopic composition and homogeneity tests, based on Songshugou Qinling Group plagioclase amphibolite example to explore the Pb isotopic in situ microanalysis applied research work in geological science.First study Pb isotopic reference materials with copper matrix in copper-mine (e.g. chalcopyrite, chalcocite, and bornite) or metallic-copper. Laboratory preliminary study found that, CuPbll (GBW(E)02003), CuPb12(GBW02137), CuPbl3(GBW02138), CuPb14(GBW02139) and CuPbl5(GBW02140) national standard reference material Pb isotopic composition is relatively homogeneous, further examination of the Pb isotopic composition of this five samples by fLA-MC-ICP-MS analysis. The analysis results show that Pb isotopic composition in CuPbl2(GBW02137) is very homogeneous, all the external precision RSDs of Pb isotope ratios were less than90ppm, and it can be external reference material for Pb isotopic in situ micro-analysis in copper-mine samples with matrix of Copper.This study also explores the Pb/Tl molar ratio, laser energy, ablation frequency, carrier gas and laser ablation systems (nanosecond excimer laser and femtosecond laser), and mass discrimination correction strategy for Pb isotope analysis. The results shown that the Pb/Tl molar ratio of1.8to5.3can be obtained high-precision Pb isotope data, is the best ratio; laser energy and denudation frequency principal effects of Pb, Tl ion signal intensities, no greater impact for mass fractionation coefficients of Pb and Tl; carrier gas (Helium and Argon gas) has a greater impact on signal intensityies of Pb and Tl ions and mass fractionation factors, Helium as a carrier gas to improve signal sensitivity, reduce the mass discrimination and fractionation effects; mass fractionation significantly reduced by266nm femtosecond laser ablation relative to193nm excimer laser, mass fractionation induced by femtosecond laser is negligible; Tl fractionation factor used for Pb isotope mass fractionation correction according to the exponential law (taking into account the differences of the fractionation factors between Tl and Pb, optimize NIST SRM997Tl isotope ratios2.38890was uesd) to obtain accurate and precision Pb isotope ratios.Meanwhile, the first report of the USGS (GSE-1G, GSC-1G and GSA-1G) and CGSG series of reference material (CGSG-1, CGSG-2, CGSG-4and CGSG-5) Pb isotopic data by fLA-MC-ICP-MS analysis, the study results showed that the GSE-1G, GSC-1G, GSA-1G, CGSG-1, CGSG-2, CGSG-4and CGSG-5Pb isotopes in the range of100～200microns are homogeneous. 266nm femtosecond laser ablation-multicollector inductively coupled plasma mass spectrometry (fLA-MC-ICP-MS) analysis of Pb isotopic in plagioclase amphibolite rock from Qinling Group, Songshugou by in situ microanalysis, and gained1.00±0.17Ga Pb-Pb isochron age, the result show that the protolith of Qinling Group amphibolite have age1.00±0.17Ga, and the results agree with previous studies.4. Experiments for Fe isotope separation and purification procedures, carried out the solution nebulizer (SN) and membrane desolvation nebulizer (DSN)-multicollector inductively coupled plasma mass spectrometry (SN/DSN-MC-ICP-MS) Fe isotopic analysis instrument parameters and analytical methods research work;266nm femtosecond laser ablation-multicollector inductively coupled plasma mass spectrometry analysis technique (fLA-MC-ICP-MS) to explore in situ Fe isotope analysis in geological samples, study the experimental conditions, to establish Fe isotope fLA-MC-ICP-MS analysis method. Fe isotope composition in Songshugou dunite was analysis by fLA-MC-ICP-MS analytical techniques.Experiments to establish the the Fe isotope separation and purification procedures, the AG MP-1M anion exchange resin can be used for samples of Fe isotope separation and purification, and with the recovery more than99%, and also can be used for the separation and purification of Cu, Zn and Co.Instrument parameters and the experimental method were Carry out for sample solution (SN) and membrane to dissolve samples (DSN)-Multi-collector inductively coupled plasma mass spectrometry (SN/DSN-MC-ICP-MS) Fe isotopic analysis, more in-depth study the MC-ICP-MS analysis of ICP parameters (RF power, nebulizer gas flow), sampling mode, resolution, and analysis of test patterns on the impact of Fe isotope analysis, obtained857Fe and δ56Fe of IRMM-014are-0.006‰±0.012‰(2s) and0.002‰±0.022‰(2s), respectively, the results are consistent with the previous studies within2s the uncertainties. Long-term external precision of δ56Fe is0.02‰(2s). Hellium was also explored for trace gas addition for study the impact of it on Fe isotope analysis, the results shown that the addition of He gas can improve the precision of Fe isotope analysis. The established SN-MC-ICP-MS Fe isotopic analysis methods used for geological samples Fe isotope analysis.The femtosecond laser ablation266nm and multi-collector inductively coupled plasma mass spectrometry technique (fLA-MC-ICP-MS) were use to explore in situ microanalysis of Fe isotopes in the geological samples, experimental conditions, laser energy (or energy fluence), laser frequency and laser ablation spot beam were explored the impact on the Fe isotope in situ microanalysis. The initial Fe isotopes fLA-MC-ICP-MS analysis method were establishment, the Fe isotopic of IRMM-014are δ56Fe=-0.001±0.011%o (2s, n=52) and δ57Fe=-0.004±0.019%o (2s, n=52), respectively, the results are good consistent with the previous studies within2s the uncertainties; the obtained long-term external precision for δ56Fe was0.02‰(2s).Take Songshugou dunite for exemple, Fe isotope composition in olivine and chromite was analyzed using fLA-MC-ICP-MS technique.更多还原