Improved in-situ Determination of Sr Isotope Ratio in Silicate Samples Using LA-MC-ICP-MS and Its Wider Application for Fused Rock Powder  

作　　者：Lüyun Zhu Ganglan Zhang Yongsheng Liu Jie Lin Xirun Tong Shao-Yong Jiang 

机构地区：[1]State Key Laboratory of Geological Processes and Mineral Resources、China University of Geosciences,Wuhan 430074,China [2]Collaborative Innovation Center for Exploration of Strategic Mineral Resources,Faculty of Earth Resource,China University of Geosciences,Wuhan 430074,China [3]School of Earth Sciences,China University of Geosciences,Wuhan 430074,China [4]Wuhan Institute of Geology and Mineral Resources,Wuhan 430205,China

出　　处：《Journal of Earth Science》2020年第2期262-270,共9页地球科学学刊（英文版）

基　　金：This research is co-supported by the National Natural Science Foundation of China(Nos.41530211,41125013,41803012);the China Postdoctoral Science Foundation(No.2017M622546);the Most Special Funds of the State Key Laboratory of Geological Processes and Mineral Resources(No.MSFGPMR01).

摘　　要：The in-situ Sr isotope determination of solid samples has the advantages of high spatial resolution and convenient and rapid sample preparation.However,due to the lack of column chemistry separation of matrix elements from Sr,the interference correction(especially the isobaric interference from 87Rb on 87Sr)becomes a big issue for high precise in-situ Sr isotope analytical results.In this study,we evaluated the influence of isobaric interference systematically and adopted an improved strategy for isobaric interference correction of Rb.Specifically,as an external standard for data calibration,an in-house silicate standard(Rb-std)was fused from pure oxide powders.The new standard(Rb-std)shows very low contents of Sr(<1 ppm),Yb(<0.09 ppm)and Er(<0.05 ppm),which directly avoid the trouble of interference of doubly charged ions and isobar,when we determinate the mass fractionation factors of Rb(βRb).Our improved method can provide more accurate data than previous researches,in which the mass fractionation were calculated from an external reference material StHs6/80-G with high Rb(30.07 ppm),Sr(482 ppm),Yb(1.13 ppm)and Er(1.18 ppm).Then,these βRb from Rb-std were applied by linear interpolation to the unknown samples for correction of 87Rb on 87Sr.The analytical results of serial international reference materials(BIR-1G,BCR-2G,BHVO-2G,T1-G and ATHO-G)demonstrate that our improved method can raise the upper limit of Rb/Sr for in-situ Sr isotope determination and reduce the relative standard deviation of results.This improvement of the upper limit of Rb/Sr(<0.33)will expand not only range of microanalysis for silicate minerals,but also bulk Sr isotope determination of volcanic rock combining with rapid fusion technique.

关 键 词：LA-MC-ICP-MS Sr ISOTOPE RATIO IN-SITU analysis interference of Rb external standard geochemistry 

分 类 号：P575[天文地球—矿物学] P59[天文地球—地质学] P624.4