LA-MC-ICP-MS独居石微区原位U-Pb同位素年龄测定  

In Situ LA-MC-ICP-MS U-Pb Isotopic Dating of Monazite

作　　者：崔玉荣[1] 周红英[1] 耿建珍[1] 李怀坤[1] 李惠民[1] 

机构地区：[1]中国地质调查局天津地质矿产研究所,天津300170

出　　处：《地球学报》2012年第6期865-876,共12页Acta Geoscientica Sinica

基　　金：国土资源部公益性行业科研专项"非锆石类富铀矿物U-Pb同位素定年方法研究"(编号:200911043-15)资助

摘　　要：独居石富含U、Th,同时具有较低的初始普通Pb含量,是U-Pb和Th-Pb同位素定年的理想对象。由于普遍存在于多种岩石中,独居石的U-Th-Pb定年具有广阔的应用前景。本文报道利用193nmArF准分子激光剥蚀系统和NEPUNE多接收器电感耦合等离子体质谱仪,对独居石进行微区原位U-Pb同位素年龄测定的新方法。运用这一新方法对独居石样品AL01、BL02和CL03进行微区原位U-Pb同位素年龄测定,获得AL01和BL02号样品的206Pb/238U年龄加权平均值分别为(288.3±1.1)Ma(n=19)和(446.8±2.3)Ma(n=41);CL03号样品的U-Pb等时线年龄为(396.8±8.8)Ma(n=55),取得了令人满意的结果。Characterized by rich U, Th and low initial Pb content, monazite is an ideal object for U-Pb and Th-Pb isotopic dating. Due to the existence of monazite in a variety of rocks, the U-Th-Pb dating of monazite has a broad application prospect. A new method is reported in this paper. The monazite samples were analyzed by using 193 nm ArF excimer laser ablation system coupled with NEPUNE multi-collector inductively coupled plasma mass spectrometer. The monazite samples AL01, BL02 and CL03 were dated by this method. The weighted average ^2066Pb/^238U ages of AL01 and BL02 were （288.3±1.1） Ma （n=19） and （446.8±2.3） Ma （n=41） respectively, and the isochron age of CL03 was （396.8±8.8） Ma （n=55）, showing satisfactory results.

关 键 词：独居石 微区原位 LA-MC-ICP-MS U-Pb同位素测年 

分 类 号：P578.921[天文地球—矿物学] P597.2[天文地球—地质学]