江西相山铀矿田如意亭剖面火山岩的年代学格架及其地质意义  

Timing and geological implications of volcanic rocks from the Ruyiting section,Xiangshan uranium ore field,Jiangxi Province,SE China

作　　者：杨水源[1] 蒋少涌[1,2,3] 赵葵东[1,2] 姜耀辉[3] 凌洪飞[3] 陈培荣[3] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074 [2]中国地质大学资源学院紧缺战略矿产资源协同创新中心,武汉430074 [3]南京大学地球科学与工程学院内生金属矿床成矿机制研究国家重点实验室,南京210093

出　　处：《岩石学报》2013年第12期4362-4372,共11页Acta Petrologica Sinica

基　　金：科技部973项目(2012CB416706);教育部重大研究项目(306007)联合资助

摘　　要：江西相山铀矿田如意亭剖面最底部的熔结凝灰岩代表了相山火山-侵入活动的开始时间，本文首次报导了该熔结凝灰岩的LA-ICP-MS锆石U-Pb定年结果，得出其形成年龄为137.30.9Ma，表明相山火山-侵入活动开始于早白垩世。此外，对如意亭剖面的两个流纹英安岩样品的锆石U-Pb定年结果分别是136.82.5Ma和136.41.5Ma，对采自如意亭剖面的流纹英安斑岩的锆石U-Pb定年结果是135.02.0Ma，对采自如意亭剖面的碎斑熔岩的定年结果是134.11.6Ma，这些定年结果结合前人已有的研究，得出相山火山-侵入杂岩的形成时代集中在135Ma左右（137~132Ma），再次证实了相山火山-侵入活动始于早白垩世，是一次集中且短暂的火山-侵入活动。本文对如意亭剖面的定年结果证实相山地区打鼓顶组和鹅湖岭组的火山岩地层应属于早白垩世。然而赣杭构造带上原先所划分的打鼓顶组与鹅湖岭组火山岩形成的时间与武夷山北坡冷水坑盆地中火山岩系并不相同，因此，打鼓顶组与鹅湖岭组地层在区域上应予重新厘定。The eruption of ignimbrite at the lowermost part of the Ruyiting section represents the starting time of the volcano-intrusive activities in the Xiangshan uranium ore field. LA-ICP-MS zircon U-Pb dating shows that the ignimbrite was erupted at 137.30.9Ma, which suggests that the volcanic-intrusive activities in the Xiangshan region began in Early Cretaceous. In addition, two rhyodacite samples from the Ruyiting section yielded zircon U-Pb ages of 136.82.5Ma and 136.41.5Ma, respectively. A thyodacitic porphyry yielded a zircon U-Pb age of 135.02.0Ma, and the porphyroclastic rhyolitic lava has an age of 134.11.6Ma. All these newly obtained precise U-Pb ages, together with previous data, demonstrate that the emplacement of the volcanic-intrusive complex took place in Early Cretaceous within a short time period of ~135Ma （137~132Ma）. Our new data together with previous published data suggest that the volcanic strata of Daguding Formation and Ehuling Formation in Xiangshan district were erupted at Early Cretaceous. However, timing of the Daguding Formation and Ehuling Formation which had been classified in Xiangshan basin from the Gan-Hang Belt and the Lengshuikeng basin from the northern Wuyi area are different. Consequently, we consider that the volcanic strata of the Daguding Formation and Ehuling Formation need to be revisited in the region.

关 键 词：熔结凝灰岩 LA-ICP-MS锆石U-PB年龄 如意亭剖面 相山铀矿田 

分 类 号：P588.14[天文地球—岩石学] P597.3[天文地球—地质学]