橄榄石中Ni、Ca、Mn含量的电子探针与激光等离子体质谱准确分析  

Accurate Determination of Ni,Ca and Mn in Olivine by EPMA and LA-ICP-MS

作　　者：郑曙[1] 胡兆初[1,2] 史玉芳[1] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,湖北武汉430074 [2]西北大学大陆动力学国家重点实验室,陕西西安710069

出　　处：《地球科学（中国地质大学学报）》2009年第1期220-224,共5页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金项目(Nos.40521001,40703006,90714010,40872003);高等学校学科创新引智计划项目(No.B07039)

摘　　要：镁铁-超镁铁岩浆岩中的橄榄石斑晶是示踪玄武岩原始岩浆组成,进而示踪地幔源区组成和演化的最重要矿物.本研究利用电子探针和激光等离子质谱两种方法对橄榄石斑晶中Ni、Ca、Mn等具有重要成因指示意义的少量-微量元素进行准确分析.采用的电子探针方法较常规电子探针分析方法可使元素的检出限降低3～18倍,并且激光等离子质谱方法对4个国际标准MPI-DING玻璃(KL2-G(玄武岩)、ML3B-G(玄武岩)、StHs6/80-G(安山岩)和T1-G(石英闪长岩))中Mg、Al、Ca、Ti、Cr、Mn、Fe、Co和Ni含量的分析结果与其推荐值大多数相差在±5%之内.两种方法对费县和四合屯同一样品获得的Ca、Ni、Co、Cr、Mg和Fe的含量相差绝大多数情况下小于10%,表明利用研究建立的电子探针和激光等离子体质谱两种方法均可准确分析橄榄石中的上述元素含量.Phenocrystal olivines in mafic and ultramafic magmatic rocks are critical minerals for trace composition of primary mantle-derived magma and in turn to study composition and evolution of the mantle. We have developed two methods for accurate determination of Ni, Ca, Mn and other elements in olivine by EPMA and LA-ICP-MS. These elements are important indicators for the basalt source compositiorL The limits of detection for these elements are within the range of 7 to 57 （10^-6） by using the proposed EPMA analytical method, which are lower than those of the routine EPMA method by a factor of 3-18. In this work, these elements in MPI-DING reference glasses （KL2-G （basalt）, ML3B-G （basalt）, StHs6/80-G （andesite） and T1-G （quartzdiorite）） were determined at a spatial resolution of 24μm by LA-ICP-MS. All the determined values of MPI-DING reference glasses agree within 8% with the reference values, and most of them agree within 5%, which demonstrated the accuracy of the established analytical methods. The EPMA and LA ICP-MS were then successfully applied to the determination of Mg, AI, Ca, Ti, Cr, Mn, Fe, Co and Ni in olivine phenocrysts from Early Cretaceous Feixian （western Shandong） and Sihetun （western Liaonin） basalts in the North China cratoru Most of the determined values in the same samples determined by EPMA and LA-ICP-MS agree within 10%. This demonstrates the accuracy of our developed EPMA and LA-ICP-MS methods.

关 键 词：EPMA LA-ICP-MS 橄榄石 微量元素 

分 类 号：P575.1[天文地球—矿物学]