Zircon U-Pb Chronology and Its Geological Implications of Mesozoic Volcanic Rocks from the Hailaer Basin
详细信息
- 责任者：Zhao Lei (State Key Laboratory of Petroleum Resource and Prospecting ; College of Geosciences ; China University of Petroleum ; Beijing 102249 ; China) ; Gao Fuhong
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(3)
- 关键词：火山岩 ; volcanic rocks ; 铀—铅计时 ; U-Pb dating ; 海拉尔盆地 ; Hailar Basin
- 页码：p.864-874
- 图表：illus., 1 table, 45 refs.
- 分类号：0801
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
This paper presents the LA-ICP-MS zircon ages of 6 rhyolite samples in the Nantun Formation(K1n) from Well Chu 2 and in the Xing’anling Group(J3xn) from Well Chu 3,to constrain the volcanic rocks’ exact formation time and their relation to the fomation and evolution of the Hailaer basin.Zircon grains from the 6 rhyolite samples are euhedral to subhedral in shape and show the typical oscillatory zoning or striped absorption with Th/U ratios range from 0.48 to 2.41,implying that they should be magmatic in origin.The 206Pb/238U ages of zircons from the rhyolite sample of the Nantun Formation(K1n) in Well Chu 2 range from 123Ma to 134Ma,with a weighted mean 206Pb/238U age of 127±2Ma,representing the formation time of the volcanic rocks,is Early Cretacesous.Zircon grains in other five rhyolite samples from the Xing’anling Group(J3xn) in Well Chu 3 show weighted mean 206Pb/238U ages of 120±1Ma,127±4Ma,125±1Ma,125±1Ma and 126±1Ma,respectively,indicating that the volcanic rocks was formed in Early Cretacesous rather than Late Jurassic as previously believed.Besides these ages,there are some captured zircons in rhyolites with the ages of 140～168Ma,which coincide with the formation time of volcanic rocks in the Tamulangou Formation in the same region.Our data shows that the volcanic rocks in the Nantun Formation and the Xing’anling Group formed in Early Cretacesous,which are close to the age of the Mesozoic volcanic activities in eastern China.Combined with the spatial variations of ages of the Mesozoic volcanic rocks in northeastern China,it is suggusted that the formation and evolution of the Hailaer basin are related to the subduction of the Paleo-Pacific plate.
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