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《Geological Science and Technology Information》 2009-03
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Evidences from Geochemistry and Zircon U-Pb Geochronology of Volcanic Rocks of Yeba Formation in Demingding Area,the East of Middle Gangdise,Tibet

CHEN Wei 1a,2,MA Chang-qian 1b,BIAN Qiu-juan 1b,HU Yuan-qing 1a,2,LONG Tao-cheng 2,YU Shui-lin 2,CHEN Dong-ming 3,TU Jiang-hai 1a,2 (1a.Graduate School;1b.Faculty of Earth Sciences,China University of Geosciences,Wuhan 430074,China;2.Geological Team of Northeast of Hubei,Xiaogan Hubei 432100,China;3.Institute of Geology Survey of Hubei,Wuhan 430022,China)  
The dacite of the Yeba Formation in Demingding,Tibet is dated(192.7±1.3) Ma by zircon SHRIMP U-Pb dating,representing the age of the formation in the area.The dacite of the Yeba Formation was formed in Early Jurassic,nearly the same time as that of volcanic rocks of the Yeba Formation in Dazi regions.The study of the features of rock combination and geochronology shows that the Yeba Formation is made up of shallow andesite,dacite,rhyolite,acid tuff with little clastic rock and carbonate rocks,and can be divided into upper,middle and lower parts.Geochemical characteristics illustrate that the rock of the Yeba Formation is the acidic volcanic rock,and may be a product of the northward subduction and reduction of the Yarlungzangbo ocean,and formed in the island arc environment.
【Fund】: 中国地质调查局矿产资源补偿费矿产勘查项目(矿调[2005]1-10]
【CateGory Index】: P597
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