大型离子探针分析熔体包裹体微量元素组成  

Determination of trace elements in melt inclusions by secondary ion mass spectrometry

作　　者：张乐[1,2] 夏小平 杨晴[1] 张万峰[1] 熊伯琴[1] 钱生平 任钟元 ZHANG Le;XIA Xiao-ping;YANG Qing;ZHANG Wan-feng;XIONG Bo-qin;QIAN Sheng-ping;REN Zhong-yuan(State Key Laboratory of Isotope Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院广州地球化学研究所同位素地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049

出　　处：《地球化学》2019年第1期1-8,共8页Geochimica

基　　金：广州市科技计划项目(201607020029);国家自然科学基金(41703023)

摘　　要：熔体包裹体是矿物在结晶过程中捕获的岩浆小液滴,记录了岩浆起源和演化等重要信息。本研究利用CAMECA IMS 1280-HR型SIMS,建立了25个熔体包裹体微量元素的分析方法。使用O_2^-一次离子束轰击样品表面,束流4～10 nA。一次离子束在样品表面的束斑直径为20～30μm。五个地质玻璃标样(NIST612、BHVO-2G、BCR-2G、TB-1G和GSD-1G)的分析结果显示,分析精度和准确度与元素单位电流信号强度存在显著相关关系。单位电流信号强度大于12 s^(-1)的元素分析精度优于10%,单位电流信号强度小于12 s^(-1)的元素分析精度优于15%(Er和Lu的分析精度优于20%)。所有元素分析结果与推荐值的偏差小于20%。使用本方法对来自夏威夷玄武岩中的熔体包裹体进行了微量元素分析,分析结果与全岩数据有较好的一致性。另外,为方便数据处理,本研究采用MATLAB编写了SIMSTraElement程序包,可以对SIMS测试的微量元素数据进行快速便捷的处理。Melt inclusions are small magma drops captured by mineral crystals during magmatic processes and record useful information regarding magmatic origin and evolution.Using CAMECA IMS 1280-HR secondary ion mass spectrometry(SIMS),this study established an analytical method for 25 trace elements measured in melt inclusions.O2-was used as the primary ion with a current of approximately 4–10 nA to bombard the sample surface.The beam ellipsoidal spot was approximately 20μm×30μm in size.The results of the five geological reference glasses(NIST612,BHVO-2G,BCR-2G,TB-1G,and GSD-1G)indicate that analytical precision and accuracy have a strong correlation with elemental concentration.The precisions for the elements with concentrations higher than 10μg/g are better than 10%(2SD),and for elements with concentrations lower than 10μg/g they are better than 15%(for Er and Lu,they are approximately 18%).The bias of all the measured elemental concentrations from their preferred values are within±20%.Using the present method,olivine-hosted melt inclusions from a Hawaiian basalt were measured.The results are consistent with the whole-rock data.Finally,a MATLAB program termed SIMSTraElement is available for public use was developed,providing fast,convenient data reduction for trace-element determination.

关 键 词：离子探针 熔体包裹体 微量元素 微区分析 玻璃标样 

分 类 号：P595[天文地球—地球化学]