Lower boundary age of the Nanhua System and the Gucheng glacial stage: Evidence from SHRIMP II dating
Lower boundary age of the Nanhua System and the Gucheng glacial stage: Evidence from SHRIMP II dating
复制标题
DOI：
10.1360/03wd0112
复制
发表时间：
2003-08
影响因子：
--
通讯作者：
Yin Chongyu;L. Dun-yi;Gao Linzhi;W. Ziqiang;Xing Yusheng;J. Ping;Shi Yu-ruo
中科院分区：
文献类型：
--
作者：
Yin Chongyu;L. Dun-yi;Gao Linzhi;W. Ziqiang;Xing Yusheng;J. Ping;Shi Yu-ruo
在新修订的《中国区域年代地层（地质年代）表》中，新元古代由原来的二分划分改为三分划分。这三个“系统”级年代地层单位自下而上依次为青白口系、南华系和震旦系。本文报道了湖南省石门县壶瓶山镇杨家坪南华系层型候选剖面火山凝灰岩的SHRIMP锆石U-Pb年龄。南华系下统泄水河组上部凝灰岩（相当于莲沱组）的锆石U-Pb年龄为758 ± 23 Ma，可作为南华系古城冰期下限的制约。下伏青白口系老山崖组凝灰岩（相当于板溪群）的锆石U-Pb年龄为809 ± 16 Ma。采样点位于青白口系上界12 m处。根据沉积速率估算其上界年龄约为800 Ma。本文的研究还解决了华南晚前寒武纪地层对比中长期存在的莲沱组是否与板溪群相当的问题。
In the newly revised Regional Chronostratigraphic (Geochronologic) Scale of China, the original bipartite division of the Neoproterozoic is changed to tripartite division. The three “system”-rank chronostratigraphic units are in ascending order of the Qingbaikou, Nanhua and Sinian Systems. This report presents SHRIMP zircon U-Pb dating on volcanic tuffs from the candidate stratotype section of the Nanhua System at the Yangjiaping section that is geographically located in Hupingshan Town, Shimen County, Hunan Province. Tuff from the upper part of the Xieshuihe Formation (equivalent to the Liantuo Formation) in the Lower Nanhua Series yields a zircon U-Pb age of 758 ± 23 Ma, which may provide a constraint on the lower limit of the Gucheng glacial stage in the Nanhua System. Tuff from the Laoshanya Formation of its underlying Qingbaikou System (equivalent to the Banxi Group) gives a zircon U-Pb age of 809 ± 16 Ma. The sampling locality lies 12 m from the upper boundary of the Qingbaikou System. According to the sedimentation rate it is estimated that the upper boundary age is about 800 Ma. The present studies also provide a resolution to the long-standing problems concerning stratigraphic correlation of the Late Precambrian in South China whether the Liantuo Formation is equivalent to the Banxi Group or not.