Uraninite is considered to be the main ore source provider of granite-hosted uranium deposits,it plays a significant role in mineralization assessment of granite and constraining the age of digenesis and uranium mineralization. Changjiang granite is a part of the Zhuguang Mountains,and is important U-bearing granite in the north of Guangdong. Uranium minerals in this granite are studied by Electron Microprobe. Results show that uranium minerals mainly fill in the spaces between minerals or are surrounded by pyrite. Uranium minerals are also found in quartz,biotite,chlorite and other minerals. The main types of uranium minerals are uraninite, pitchblende,uranothorite and uranophane. The chemical ages of uraninite and pitchblende dated by Electron Microprobe can be divided into three groups,about 155 Ma,106 Ma and 74 Ma. The first group represents the formation age of Changjiang granite mass,and the second and third groups represent multiple stages of uranium mineralization. From rock formation to about 106 Ma,the composition of uraninite has not changed significantly. Obvious U activation and migration did not happen until 74 Ma,so the main uranium mineralization of Changjiang granite may have occurred at about 74 Ma or later.%晶质铀矿被认为是花岗岩型铀矿成矿的主要矿源提供者,在评价岩体的含矿性和确定成岩成矿年龄方面有重要意义.长江岩体属于诸广山复式岩体的一部分,是粤北地区重要的产铀花岗岩体,本文利用电子探针对该岩体中的铀矿物进行研究.结果表明:长江岩体中的铀矿物多以充填或被黄铁矿包围的形式存在,或者分布于石英、黑云母、绿泥石等矿物中;铀矿物类型主要有晶质铀矿、沥青铀矿、铀石、铀钍石四种.晶质铀矿/ 沥青油矿的化学年龄值可分为三组:~ 155 Ma、~ 106 Ma 和
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