激光剥蚀电感耦合等离子体联用条件优化及其应用

Optimization and Application of Combined Condition of Laser Ablation Inductively Coupled Plasma

锆石U-Pb定年是近些年来发展起来的一种很成熟的定年方法,快速、简单。该次研究在ArF193nm激光剥蚀器和iCAPQ电感耦合等离子体质谱仪之间设计添加了外置匀化器,从而使激光剥蚀出来的气溶胶可进行混匀后再被载气载入等离子体质谱仪,这不仅提高了等离子体质谱仪的信号稳定性,同时大大提高了锆石测试区域的精密度和准确度,为线状剥蚀扫描进行不同成分域定年的开展提供了便利条件。利用通过加载外置器皿的联接条件对新疆天山造山带北部的二长花岗岩11k88进行线状剥蚀取样U-Pb年龄测试,显示加载最优外置器皿后,线状剥蚀取样的测试结果与前人进行SHRIMP U-Pb年龄测定结果在误差范围内一致。表明加载人工设计的匀化器进行激光器和等离子体质谱仪之间的联接优化,可进行线状浅剥蚀取样方式的锆石U-Pb年龄和微量元素测定,这将拓展LA-ICP-MS在地质年代学研究中的应用。

At present, zircon U-Pb dating is a very mature dating developing method. Because it is fast and simple. In this study, an external homogenizer has been designed between the ArF193nm laser ablation device and the iCAP Q inductively coupled plasma mass spectrometer, so that the laser ablated aerosol can be mixed and then loaded by the carrier gas into the plasma mass spectrometer. It not only improves the signal stability of the plasmonic mass spectrometer, but also greatly improves the precision and accuracy of the zircon test area, and provide a convenient condition for the linear denudation scan to carry out the different compositional domain dating. U-Pb age test is performed on the 11k88 which is collected in the northern part of the Tianshan orogenic belt in Xinjiang by using the loading condition of the external vessel. It is showed that after loading the optimal external vessel, the results of the linear denudation sampling test are comparable to the previous generations. The measurement results of SHRIMP U-Pb age are consistent with the error range. It indicates that the artificially designed homogenizer is used to optimize the connection between the laser and the plasmon mass spectrometer, and the U-Pb age and trace elements of zircon can be determined by the linear shallow denudation sampling method. It will expand the application of the LA-ICP-MS.