SHRIMP zircon U-Pb dating of the Luojiamen Formation in western Zhejiang Province and its geological implications

Zircon dating of tuff bedding is reported for the first time from the Luojiamen Formation in the Heshangzheng Group. Two groups of tuff SHRIMP zircon U-Pb ages of the Luojiamen Formation were obtained, i.e., 824±5Ma and 832±6Ma together with 791±15Ma. In addition, the zircons of granite conglomerate from the bottom of the Luojiamen Formation were also measured, with the SHRIMP zircon U-Pb age being 901±9Ma, which further constraints the stratigraphic age of the Luojiamen Formation. Zircon dating of the Luojiamen Formation has completed the stratigraphic age of the Heshangzhen and Shuangxiwu groups which lie over and below the interface of the Shengong Movement, which is of great importance for stratigraphic correlation and determination of the stratigraphic framework of the Jiangnan Orogenic Belt. Combined with the age of the Shuangxiwu Group which underlies the Luojiamen Formation in angle unconformity, these stratigraphic ages provide the basis for time constraints and contrast of the Shengong Movement.