中文摘要：

采用锆石SHRIMP微区u—Pb测年技术，测定了江西相山铀矿田火山一侵入杂岩的时代。采自于相山西北部的石马山和西部南陂的鹅湖岭组碎斑熔岩的SHRIMP锆石唧b／如表面年龄加权平均值分别为（134．6＋1．0）Ma（MSWD=I．5）和（134．1±1．0）Ma（MSWD=0．65），可以限定相山第二火山喷发旋回的结束时代为134Ma；采自于相山北部巴泉和南部浯漳的似斑状花岗岩的SHRIMP锆石^206pb／^238U表面年龄加权平均值为（133．3±O．8）Ma（MSWD=0．82）和（134．7±0．9）Ma（MSWD=I．08），与碎斑熔岩的年龄在误差范围内基本一致，结合野外地质事实和前人的地球化学测试分析结果。确认碎斑熔岩和似斑状花岗岩属于同期、同来源的火山喷发一侵入的产物，形成于134～133Ma。书堂钻孔ZKlllA一1中打鼓顶组顶部流纹英安岩的锆石^206Pb／^238U表面年龄加权平均值为（141．6＋1．7）Ma（MSWD=0．9）。表明第一旋回火山喷发的时代应结束于142Ma，大部分属于晚侏罗世火山活动。岗上英钻孔岩心中石英二长花岗斑岩的锆石~6pb／叼表面年龄加权平均值为（136．4＋1．0）Ma（MSWD=1.7），如意亭剖面第二采石场流纹质英安斑岩的锆石唧b／z38U表面年龄加权平均值为（137．4＋1．7）Ma（MSWD=1.11）；推测这两者应属于早晚两期火山喷发旋回间隔期的次火山一侵入岩．进而限定136～137Ma为相山两期火山喷发旋回的间隔时期。综合前人资料和本文测试分析结果．可将相山火山喷发第二旋回鹅湖岭组的时代限定为136～133Ma，应属于早白垩世的火山活动．进而认为将相山地区“鹅湖岭组”的地层时代划归为早白垩世较为合适。

英文摘要：

The volcanic-intrusive complexes were dated by the SHRIMP U-Pb dating method of zircons from the Xiangshan uranium orefield, Jiangxi Province. SHRIMP U-Pb dating of zircons from 7 volcanic rocks yielded 206Pb/238U concordant ages from 133Ma to 142Ma. The weighted mean ages of two porphyroclastic lava samples are 134.6＋_1.0Ma （MSWD=I.5） and 134.1＋l.0Ma （MSWD=0.65）, respectively, which constrain the latest volcanic eruption in Xiangshan area at 134Ma. Two sub-porphyritic granites ~om Baquan in northern and Wuzhang in southern Xiangshan uranium orefield have ages of 133.3___0.8Ma （MSWD=0.82） and 134.7＋0.9Ma （MSWD=I.08）. The consistent ages of granite porphyry with porphyroclastic lava within the error range indicate that these two types of＂ rocks were approximately simultaneously erupted or/and then intruded, probably with similar origins, as also supported by field evidence and previous geochemical analyses. A rhyodacite sample obtained from drill hole No.ZKlllA-1 in the upper part of the Daguding Formation at Shutang in western Xiangshan has age of 141.6±1.7Ma （MSWD=0.9）, suggesting that the first-cycle of the volcanic eruption should have ended at about 142Ma, most probably during the Late Jurassic. The intrusive age of a quartz-monzonite granite-porphyry sample from drill hole No. ZK19-2 in Gangshangying area is 136.4±1.0Ma （MSWD=I.7）, and the age of rhyodacite-porphyry from the Ruyiting section is 137.4＋1.7Ma （MSWD=I.ll）, indicating an interval age of 136-137Ma between the first and the second cycle of volcanic eruption, and both the granite-porphyry and the rhyodacite-porphyry intruded during the interval time of two volcanic movement cycles. The dating results obtained by the authors and the previous researchers show that the second-cycle of the volcanic-intrusive movement in Xiangshan area ranged from 136Ma to 133Ma in time, belonging to early Cretaceous volcanic event. It is also vrovosed that the Ehuling Formation in Xianffshan area should be Early Cretaceous in age.