中文摘要：

铀成矿年龄是铀矿床研究的重要内容，如何准确有效的测定铀矿床的成矿年龄一直是铀矿地质工作者不断探索的课题。应用电子探针化学定年方法对陕西丹凤光石沟伟晶岩型铀矿床中晶质铀矿进行了微区定年工作，光石沟铀矿床中晶质铀矿的微区特征及成分信息显示，晶质铀矿形成后一直处在封闭体系之中，后期没有经历热液流体的蚀变改造。本次获得两颗晶质铀矿的成矿年龄分别为（407．6±8）Ma和（416．9±10）Ma，与该矿床的U-Pb同位素稀释法测定的晶质铀矿年龄一致。

英文摘要：

The dating of uranium mineralization is of great important to the researchers in uranium deposits ; and it＇s accuracy has always been a great challenge that uranium geologists are facing. In this paper, with the appli- cation of EPMA Chemical dating method, the compositional and micro-morphologic characteristics of the uraninite from Guangshigou uranium deposit were studied. The study shows that the uraninite has been in a closed system since its formation, and has not been altered by hydrothermal fluids ; the ages of two uraninites is （407.6 ± 8） Ma and （416.9 ± 10） Ma, respectively, which is consistent with ages from U-Pb isotope dilution.