摘要
首次报道了扬子克拉通黄陵背斜南部由辉绿岩脉、花岗闪长岩脉和正长花岗岩脉组成的新元古代早期小型岩墙.辉绿岩脉和花岗闪长岩脉的锆石U-Pb定年结果分别为856±6.4 Ma和860±6.0 Ma.全岩主量和微量元素数据显示岩墙中辉绿岩具有高Pb含量,且Ba/Nb和La/Nb比值变化较大,而花岗闪长岩脉和正长花岗岩脉样品的Y和Nb含量较低,结合继承性锆石年龄分布特征,暗示岩墙形成过程中遭受了不同程度的年轻岛弧地壳物质混染.黄陵南部~860 Ma小型岩墙的发现,表明扬子克拉通在早于该时期已进入后碰撞的伸展构造环境.综合区域已有资料,认为扬子克拉通前寒武纪基底的裂解在时空上均表现出较大差异.
It reports the first occurrence of Early Neoproterozoic dike swarm located in the southern Huangling anticline,Yangtze craton,which is composed of diabase,granodiorite and syengranite.Zircon U-Pb dating of diabasic and granodioritic dikes yields weighted mean 206Pb/238U ages of 856±6.4 Ma and 860±6.0 Ma,respectively,which are interpreted as the formation ages of the dike swarm.Whole-rock geochemical results show that diabasic dikes show high contents of Pb,variable Ba/Nb and La/Nb ratios,however,the granodioritic and syengranitic dikes have relative low contents of Y and Nb.In combination with age spectrums of inherited zircons from analytical dikes,it is proposed that the dike swarm experienced a certain crustal contamination of juvenile island arc during formed process.Document of ca.860 Ma dike swarm in the southern Huangling anticline indicates that the Yangtze craton entered into the post-collisional extensional environment before 860 Ma.Therefore,it is inferred that Precambrian basement breakup of the Yangtze craton shows difference in spatial-temporal distribution.
作者
蒋幸福
彭松柏
韩庆森
Jiang Xingfu;Peng Songbai;Han Qingsen(School of Earth Sciences,State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China;School of Earth Sciences,China University of Geosciences,Wuhan 430074,China;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2021年第6期2117-2132,共16页
Earth Science
基金
东华理工大学核资源与环境国家重点实验室开放基金(No.NRE1911)
国家自然科学基金项目(No.41272242)
东华理工大学博士启动基金项目(No.DHBK2015321).
关键词
扬子克拉通
黄陵背斜南部
~860
Ma岩墙
新生地壳混染
伸展构造环境
岩石学
Yangtze craton
southern Huangling anticline
~860 Ma mafic dike
Juvenile crustal contamination
extensional environment
petrology
