LA-ICP-MS zircon U-Pb dating of the rhyolite from the Zhonglü Group,northwestern Zhejiang Province, and its chronostratigraphic significance
The Zhonglü Group,outcropped in the northwestern part of Zhejiang Province,is a sequence of strongly-deformed,low-grade metamorphic clastic and volcanic rocks.It is overlaid unconformably by the Xiuning Formation,Nanhua period.Traditionally it is compared to the Shuangqiaoshan Group in the northeastern part of Jiangxi Province.This paper reports the LA-ICP-MS zircon U-Pb age of the rhyolite from the Zhonglüi Group.The age of the Zhonglü Group is important to remodeling stratigraphic classification and correlation of Precambrian,and the mineralization geological background and conditions in the east part of South China are important as well.Sample A120408-4,collected from the north of Suzhuang fault,the middle-upper part of the Zhonglü Group,is massive rhyolite,which had been heavily foliated.Thirty-eight of the zircons were analyzed with LA-ICP-MS,and a weighed-mean U-Pb age of (777.1 ± 3.6) Ma was obtained.Considering the stratum and metamorphic deformation characteristics,we draw the following conclusion:The main part of the Zhonglüi Group is equivalent to the Shangshu Formation,Heshangzhen Group.Both of them belong to different facies of the same period,and they developed under the global tectonic background of Rodinia supercontinent cracking.The Zhonglü Group represents the cracking of the Yangtze ancient continent in the late neoproterozoic.
NETL
NSTL
万方数据
维普
