摘要
滩间山群是指出露于青藏高原北部柴达木盆地北缘的一套早古生代的浅变质火山岩-沉积岩地层。变质火山岩主要由玄武岩、玄武安山岩组成,夹少量变质英安岩。变质沉积岩主要由绢云片岩、含炭绢云片岩、大理岩以及砂岩、砾岩组成。前人认为这套地层的时代为晚奥陶世。野外地质研究发现,这套地层遭受多期强烈构造变形和低绿片岩相变质作用的改造。同位素年代测试显示,其中变质英安岩的单颗粒锆石U-Pb测年的上交点年龄为(953±27)Ma,下交点年龄为(486±13)Ma,结合锆石形态特征以及区域地质资料分析,认为滩间山群的时代应为早奥陶世。
The Tanjianshan Group refers to a Early Paleozoic low-grade met am orphic volcanic-sedimentary suite exposed along the northern margin of the Qai dam basin in the northern Qinghai-Tibet Plateau.The metamorphic volcanic rocks are composed mainly of basalts and basaltic andesites with some dacites.The metamorphic sedimentary rocks consist dominantly of sericite schists,carbonace ous sericite schists and mar-bles,as well as metasandstones and conglomerates .Field geological studies of the Tanjianshan Group suggest that the rocks have undergone polyphase strong tectonic deformation and low greenschist facies meta mor-phism.Single zircon U-Pb dating gives an upper intercept age of 953± 27Ma and a lower intercept age of 486±13Ma.A combination of a study of the regional geological data and zircon morphology indicates an Early Ordovi cian age for the Tanjianshan Group.
出处
《地质通报》
CAS
CSCD
北大核心
2003年第1期28-31,共4页
Geological Bulletin of China
基金
地质矿产部人才基金项目(9820)
中国地质调查局攻关项目(950200803)
