地质样品Sr同位素激光原位等离子体质谱(LA-MC-ICP-MS)测定  

In-situ Sr isotopic measurement of natural geological samples by LA-MC-ICP-MS.

作　　者：杨岳衡 吴福元 谢烈文 杨进辉 张艳斌 

机构地区：[1]Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China

出　　处：《岩石学报》2009年第12期3431-3441,共11页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(40773008和40325006)资助

摘　　要：Sr同位素在研究岩浆演化及其源区具有重要的示踪作用。MC-ICP-MS的出现为具有高Sr含量地质样品的激光原位Sr同位素测定变成了现实。本文利用Netpune MC-ICP-MS和193nm准分子激光联机,通过滨珊瑚、斜长石、磷灰石和钙钛矿等系列实验,建立了激光原位Sr同位素测定方法。实验结果表明,激光Sr同位素测定中Kr、Rb和稀土元素二价离子的干扰能够有效扣除,而钙聚合物的干扰在Neptune型MC-ICP-MS并不显著。不同激光参数的实验表明,大激光束斑产生更高信号强度,因而Sr同位素精度更高,同一激光束斑大小,激光脉冲频率对Sr同位素精度无明显影响。Strontium (Sr) isotopes are important indicators and tracers in deciphering the sources and evolution of magmas. Since the development of multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS), in-situ Sr isotopic analyses in high spatial resolution have become widely available and feasible for minerals with high Sr concentrations. We developed in-situ Sr analytical procedure on Netptune MC-ICP-MS coupled with 193 nm excimer laser, based on systematical analysis of porites coral, plagioclase, apatite and pervoskite. It is shown that the interferences of Kr, Rb and REEs can be reasonably corrected, and that the interferences of Ca argide/dimmer species are limited in our Neptune instrument. Analysis with spot size of 63, 94 and 127 mu m and different repetition rates shows that the larger pit size produces the higher signal intensity, hence higher precision of Sr isotopic data, however, the repetition rate does not have a significant influence on the precision.

关 键 词：地质样品 同位素测定 激光原位 等离子体质谱 natural isotopic measurement inductively coupled plasma analytical procedure spatial resolution mass spectrometry analysis in-situ PORITES coral excimer laser 实验 激光束 significant development 准分子激光 spot size 

分 类 号：P58[天文地球—岩石学]