New Geological time scale of Late Precambrian in China and geochronology

Abstract：The newly marked Precambrian stratigraphic column of China was discussed by the Subcommission on Precambrian of National Commission on Stratigraphy of China on November 24, 2009. According to the common understanding reached at this meeting, Changcheng System comprising Changzhougou, Chuanlinggou, Tuanshanzi and Dahongyu Formations is limited in 1.8-1.6 Ga, whereas the Jixian System consisting of Gaoyuzhuang, Yangzhuang, Wumishan, Hongshuizhuang and Tieling Formations is limited in 1.6-1.4 Ga. The unnamed system (1.4-1.0 Ga) only includes Xiamaling Formation in the Jixian section. The Qingbaikou System composed of Luotuoling and Jing’eryu Formations is limited in 1.0-0.78 Ga. The Nanhua System is between 780-635 Ma and the Sinian System is between 635-542 Ma in age. According to a series of SHRIMP U-Pb dating data from late Precambrian in Jiannan orogenic belt, the strata should be assigned to the upper part of the Qingbaikou System. Moreover, new zircon U-Pb dating data obtained in North China Platform reveals the existence and distribution of the volcanic province. In dealing with the basic global geodynamics, it is useful to set up a basic late Precambrian section with unified and high-precision chronological dating.