氟碳铈矿U-Pb定年技术研究

A Study of U-Pb Dating Technology of Bastnaesite

本文以稀土矿床中的常见副矿物氟碳铈矿为研究对象,通过优化实验条件和仪器参数,分别采用激光剥蚀多接收电感耦合等离子体质谱法(LA-MC-ICP-MS)和同位素稀释热电离质谱法(ID-TIMS)对氟碳铈矿样品SAM进行U-Pb定年技术研究,并将此两种方法得到的结果进行对比。LA-MC-ICP-MS得到的U-Pb年龄为(409±18)Ma(N=27,MSWD=4.5),ID-TIMS得到的206Pb/238U U-Pb年龄为(407.8±3.3)Ma(N=3,MSWD=0.029),两种方法得到的U-Pb年龄结果在误差范围内一致。通过比较两种方法的实验流程和结果,总结了各自的优缺点,为氟碳铈矿U-Pb定年方法选择提供了参考依据。

In order to solve the problem of lack of suitable minerals for U-Pb dating in rare earth elements（REE） ore deposits, the authors chose the common accessory mineral bastnasite as the research object in the paper. With the optimization of the experimental conditions and instrumental parameters, U-Pb dating of bastnaesite SAM was carried out by laser ablation multi-collector inductively coupled plasma mass spectrometry（LA-MC-ICP-MS） and isotope dilution thermal ionization mass spectrometry（ID-TIMS）. The U-Pb ages of bastnaesite SAM obtained by LA-MC-ICP-MS and ID-TIMS are（409±18） Ma（N=27, MSWD=4.5） and（407.8±3.3） Ma（N=3, MSWD=0.029）, respectively. The consistent U-Pb dating results within error suggest that the proposed methods for in situ LA-MC-ICP-MS and ID-TIMS U-Pb dating of bastnaesite are effective.