地质样品中Fe同位素整体及原位分析方法研究及其地质应用

发布时间：2018-07-09 20:21

  本文选题：Fe同位素 + 化学分离　； 参考：《西北大学》2017年硕士论文

【摘要】：本文利用大型多接收等离子体质谱(Nu Plasma 1700 MC-ICP-MS,NP-1700)建立了溶液进样和飞秒激光剥蚀进样测试地质样品中Fe同位素组成的分析方法,并研究了二里河铅锌矿矿床的Fe同位素组成特征。主要的研究内容包括:进一步完善了地质样品的化学溶解方法,改进了 Fe同位素的分离纯化流程;建立了溶液进样MC-ICP-MS准确测定地质样品中Fe同位素组成的测试方法,研究了仪器条件(锥组合、进样方式)和样品条件(酸度效应、浓度效应)对Fe同位素组成测定的影响;综合Ni内标法与SSB法(标准-样品交叉法)校正质谱质量歧视效应,研究了 Fe/Ni信号比对Fe同位素测试的影响;利用本研究所建立的化学处理方法及分析方法,测试了部分国际标准岩石样品的Fe同位素组成,分析结果与文献报道值在2s误差范围内完全一致,证明了所建立方法的可靠性;同时,基本建立了原位微区分析Fe同位素的方法,并利用所建立的方法分析了两个天然黄铁矿的Fe同位素组成,与溶液法所得结果在误差范围内完全一致。1.在前人研究的基础上,进一步完善了地质样品的化学溶解方法,改进了 Fe同位素的分离纯化流程,用HF和HNO3(体积比3:1)可以完全溶解大部分地质样品,之后转为HC1介质待化学分离;利用AGMP-1M阴离子交换树脂分离纯化Fe同位素,依次用2、4、8mol/LHCl清洗树脂,提高了回收率(大于99%),所建立化学方法的全流程Fe 本底7ng。2.利用NP-1700的高分辨模式(M/△ M=14,000 RP)将Fe同位素的多原子离子干扰谱峰(如:[40Ar14N]+、[40Ar160]+等)与Fe同位素信号完全分离,分别采用湿法和干法进样对部分国际标准全岩粉末样品的Fe同位素组成进行了测定,在2s误差范围内,两种进样方式的分析结果与文献参考值完全一致,且湿法进样δ56Fe的测量精度优于0.029‰,而干法进样δ56Fe的测量精度优于0.084‰。通过条件实验研究表明:湿采样锥+湿截取锥组合的仪器稳定性最好,样品和标样需要进行严格的HNO3介质酸度匹配,而Fe的浓度无需严格的匹配,Ni内标结合SSB法校正仪器质量歧视可以显著提高测试的稳定性。3.基本建立原位微区分析单矿物中Fe同位素的方法,探索了激光剥蚀斑束和频率对Fe同位素测试影响,并利用所建立的方法分析了两个天然黄铁矿的Fe同位素组成,化学法所得结果在2s误差范围内完全一致。4.利用本文建立的方法分析了二里河铅锌矿硫化物闪锌矿、磁黄铁矿、黄铜矿和黄铁矿中的Fe同位素组成,对该矿床的Fe同位素特征进行了初步讨论。
[Abstract]:In this paper, using Nu Plasma 1700 MC-ICP-MSNP-1700, an analytical method for the determination of Fe isotopic composition in geological samples by solution injection and femtosecond laser ablation has been established, and the characteristics of Fe isotopic composition of the Erlihe Pb-Zn deposit have been studied. The main research contents are as follows: the chemical dissolution method of geological samples has been further improved, the separation and purification process of Fe isotopes has been improved, and a method for the accurate determination of Fe isotopic composition in geological samples by solution injection MC-ICP-MS has been established. The effects of instrument conditions (cone combination, sample injection) and sample conditions (acidity effect, concentration effect) on the determination of Fe isotopic composition were studied, and the mass discrimination effect of mass spectrometry was corrected by combining Ni internal standard method and SSB method (standard sample cross method). The influence of Fe / Ni signal ratio on Fe isotope measurement was studied, and the Fe isotopic compositions of some international standard rock samples were measured by the chemical treatment method and the analytical method established in this paper. The analytical results are consistent with the reported values in the range of 2s, which proves the reliability of the established method, and establishes the method of in situ microanalysis of Fe isotopes. The Fe isotopic compositions of two natural pyrites are analyzed by using the established method. The results are in good agreement with the results obtained by the solution method within the error range. On the basis of previous studies, the chemical dissolution method of geological samples is further improved, and the separation and purification process of Fe isotopes is improved. Most geological samples can be completely dissolved by HF and HNO _ 3 (volume ratio 3:1). The iron isotopes were purified by AGMP-1M anion exchange resin, and then washed with 2o 4 mol / L HCl, the recovery rate was increased (> 99%), and the whole process of Fe background was 7ng.2. The interference spectra of polyatomic ions (such as [40Ar14N], [40Ar160]) of Fe isotopes are completely separated from Fe isotopic signals by NP-1700 high resolution mode (M / M14000 RP). The Fe isotopic compositions of some international standard whole rock powder samples were determined by wet and dry injection, respectively. Within the error range of 2 s, the analytical results of the two injection methods are in full agreement with the reference values in the literature. The measurement accuracy of wet sampling 未 56Fe is better than 0.029 鈥，

本文编号：2110544