中文摘要：

牛山岩体位于长江中下游地区繁昌火山盆地内,为一钻孔揭露的隐伏花岗斑岩岩体。近年来,勘探发现了与该岩体密切相关的铜、金、铅、锌多金属矿化。应用LA-ICP-MS锆石微区分析技术对该岩体进行了精确定年。岩体含有大量岩浆成因锆石,以高的Th/U比和振荡结晶环带为特征,17个测点的206Pb/238U年龄加权平均值为（121.8±1.9）Ma,属于长江中下游地区白垩纪岩浆晚期活动的产物。该岩体的精确定年和成矿发现,为本地区火山盆地内寻找铜、金矿开辟了新的前景。

英文摘要：

The Niushan intrusion in the Fanchang volcanic basin located in the Middle and Lower Yangtze region,is a concealed granite-porphyry rock exposed by a drill. In recent years,the copper,gold,lead,zinc polymetallic mineralization closely related to this intrusion was revealed in exploration. LA-ICP-MS zircon in-situ analysis technique was used to determine the accurate age of this intrusion. The intrusion have large amounts of magmatic zircons characterized with high Th/U ratios and crystal ring oscillators,the weighted average 206Pb/238U age of 17 measuring points being （121.8±1.9）Ma,belonging to the products of Late Cretaceous magmatism in the Middle and Lower Yangtze regions. The accurated dating and mineral discovery of the intrusion provide a new prospect for looking for copper and gold deposits in volcanic basins.