滇东北巧家地区新元古界澄江组SHRIMP锆石U-Pb年龄及其地质意义
SHRIMP ZIRCON U-Pb AGE AND ITS GEOLOGICAL SIGNIFICANCE OF NEOPROTEROZOIC CHENGJIANG FORMATION IN QIAOJIA AREA, NORTHEAST YUNNAN
陆俊泽 1江新胜 1王剑 1卓皆文 1熊国庆 1崔晓庄1
作者信息
- 1. 国土资源部成都地质矿产研究所,四川成都 610081;国土资源部沉积盆地与油气资源重点实验室,四川成都 610081
- 折叠
摘要
澄江组沉积时限对华南新元古界地层划分对比及古大陆再造具有重要意义.笔者从滇东北巧家地区的凝灰岩夹层中获得大量岩浆型锆石,并对其进行了SHRIMP锆石U-Pb年代学研究.获得了两组有效的锆石206Pb/238U加权平均年龄,分别为785 Ma±12 Ma和828 Ma±8.3 Ma.综合研究认为,785 Ma±12 Ma代表了澄江组中部的凝灰岩夹层的形成时代,进一步限定了滇东北澄江组底界年龄为800 Ma左右,区域上可与川西南苏雄组、开建桥组进行对比.此外,828 Ma的锆石年龄与新元古代早期830 Ma～820Ma的岩浆活动事件相当,因此获得的两组锆石206pb/238U年龄代表了可能与罗尼迪亚超大陆裂解有关的两次幕式岩浆活动的记录.
Abstract
The determination of sedimentary timelimit of Chengjiang Formation plays very important role in stratigraphic division,correlation of Neoproterozoic strata and reconstruction of paleocontinent in Southern China.Magmatic zircons from tuff interlayer in the middle of Chengjiang Formation in Qiaojia area,northeast Yunnan Province,were selected to carry out high-precision SHRIMP U-Pb chronological study.Two sets of effective weighted average 206Pb/238U ages of 785 Ma±12 Ma and 828 Ma±8.3 Ma were obtained.The former represents the formation age of tuff interlayer in the middle of Chengjiang Formation and limits the bottom boundary age of 800 Ma for the Chengjiang Formation in northeast Yunnan Province,which can be correlated with Suxiong Formation and Kaijianqiao Formation in southwest Sichuan Province.In addition,the latter age is identical with the time limit (830 Ma～820 Ma) of magmatic events in the early Neoproterozoic.Therefore,the two weighted mean 206pb/238U ages are the records of two episodic magmatic activities related to the splitup of Rodinia.
关键词
华南/新元古界/澄江组/SHRIMP/锆石U-Pb年龄Key words
South China/Neoproterozoic/Chengjiang Formation/SHRIMP/zircon U-Pb age引用本文复制引用
基金项目
国家自然科学基金重点项目(41030315)
中国地质调查局计划项目(1212011121105)
国家自然科学基金面上项目(41072088)
出版年
2013
NETL
NSTL
维普
万方数据