LA-MC-ICP-MS独居石微区原位U-Pb同位素年龄测定

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193 nm ArF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.

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

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 206Pb/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.