Helix SFT惰性气体质谱仪分析矿物包裹体中氦同位素组成  

Helium Isotope Composition of Inclusions in Mineral Grains Using Helix SFT Noble Gas Mass Spectrometer

作　　者：李军杰[1,2] 李剑[1] 刘汉彬[2] 张佳[2] 金贵善[2] 张建锋[2] 韩娟[2] 

机构地区：[1]中国科学院渗流流体力学研究所,河北廊坊065007 [2]核工业北京地质研究院,北京100029

出　　处：《地质学报》2015年第10期1826-1831,共6页Acta Geologica Sinica

基　　金：中核集团地矿事业部铀矿地质科研项目(编号测D1101)资助的成果

摘　　要：氦同位素组成在地球大气圈、地壳及地幔各圈层具有不同的元素丰度和同位素比值,变化范围达数个量级,而且氦作为惰性气体中质量最轻的元素,其稳定性好,迁移能力强,因此将其同位素作为地质过程和物质来源的天然示踪剂倍受重视,被广泛地应用于地学研究的各个领域,而能否对于岩石样品中氦同位素组成进行准确分析,成为了氦同位素作为示踪剂的一个关键问题。本文利用Helix SFT惰性气体质谱仪对岩石矿物包裹体内的氦同位素组成测定方法进行了研究,建立了样品的压碎及气体提取纯化装置,通过进一定体积的标准氦气,计算出仪器的灵敏度,在此基础上对整套系统的静态本底进行了测定。对仪器本身的离子倍增器的接收效率进行了探讨,使其可以准确对3 He进行准确测定。以大气中氦同位素为标准并进行多次测定,获得了氦同位素测量的质量歧视校正因子。通过对实际样品黄铁矿包裹体中氦同位素组成的测定,获得了稳定性很好的同位素比值数据,其精度可达99%。通过建立合理的压碎装置,利用该仪器对氦同位素组成分析的独特优势,可以满足对于岩石矿物包裹体中氦同位素组成的精确测定,满足其在地质科研领域的应用研究需要,进而对基础科学研究起到支撑作用。The helium element abundance and the isotope composition are different among the atmosphere,crust and mantle,with range covering magnitudes.As the lightest element of the rare gas group,helium is very stable and has strong migration ability,so it is frequent used as tracer in earth science.Whether the helium isotope composition can be measured precisely becomes the key point for the utilization of the helium isotope as geological tracer.In this paper,we carry out research about the method of analyzing the helium isotope composition of the inclusions of mineral with the Helix SFT noble gas mass spectrometer.By building the crusher and purification system the background of the whole system was measured on the basis of the sensitivity measurement of the instrument through certain volume of standard helium.This stady discussed the efficiency of the multiplier of the instrument in order to precisly measure 3 He.The calibration factor of the mass discrimination of the Helium isotope measurement was obtained through the measurement of the Helium in air.Through the measurement of the Helium isotope in the inclusion of the pyrite samples,we obtained high reproducible isotopic ratio data,with precision as high as 99%.Through the establishment of the crusher and usage of the unique advantage of the instrument for the helium isotope analysis,the instrument can analyze the helium isotope of the inclusions of the ore and mineral,meeting the need of the geological research and supporting for the basic science research.

关 键 词：氦同位素 静态本底 离子倍增器效率 质量歧视 压碎法 包裹体 

分 类 号：P597[天文地球—地球化学] P575[天文地球—地质学]