中文摘要：

帽峰岩体是下庄铀矿田最重要的赋铀矿岩体，准确确定该岩体的成岩年龄和演化历史是正确认识下庄矿田铀成矿作用的关键。本文采用锆石激光探针U-Pb法确定了337矿床范围内帽峰岩体的成岩年龄为238．2±2．3Ma，是印支期岩体，而不是先前认为的燕山期岩体。公认的337矿床铀成矿年龄是138Ma，巨大的矿岩时差表明337矿床不是先前所认为的典型岩浆热液型铀矿床。

英文摘要：

Maofeng pluton is the most important uranium-host granite in Xiazhuang uranium orefield. The accurate granite formation age and its evolution history is crucial for understanding the mineralization in this district. LA -ICPMS zircon dating was applied in this paper and found the formation age of Maofeng pluton is 238.2±4-2.3 Ma which suggests that Maofeng pluton was produced in the Indosinian magmatic event. Uranium mineralization age of No. 337 deposit is commonly reconganized to be 138 Ma. Therefore No. 337 uranium deposit was not the typical magma hydrothermal deposit due to the long time gap between the pluton formation and the uranium mineralization.