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针对重庆东南秀山中溪板溪群顶部凝灰岩及湖南新化木瓜坪江口组底部火山角砾岩进行的SHRIMP U-Pb年代学研究结果表明:板溪群顶部(即青白口系顶界)年龄为(786±11)Ma,江口组底部(即南华系底界)年龄为(785±11)Ma,这一测试结果与中国地层委提出的青白口系顶界、南华系底界780 Ma的数据相吻合。针对南华系划分的混乱局面,认为南华系地层的划分应回到“南华大冰期”的沉积相应,与国际地层表中的成冰系(纪)相对应的起点上来;而板溪群则是新元古代裂谷系起点的楔状充填体,二者不能混为一体。
A SHRIMP U-Pb chronological study on volcanic breccias in the bottom of Banxi Group in Zhongxi, Xuxi, Chongqing, in southeastern Xishan, Chongqing, and in the bottom of Pingjiangkou Formation in Xinhua Papaya, Hunan Province, shows that the age of the top of Banxi Group (786 ± 11) Ma. The age of the bottom of Jiangkou Formation (ie, the bottom of South China System) is (785 ± 11) Ma. This test result is consistent with the data of 780 Ma at the top of the Qingbaikou System and the South China System proposed by the Chinese Geological Commission Match. In view of the chaotic situation of the division of the South China System, it is considered that the division of the South China Stratigraphy should be returned to the deposition of the “South China Sea Great Ice Age” and correspond to the starting point of the ice formation system in the international stratigraphic table; It is the wedge-shaped filling body at the beginning of Neoproterozoic rifting system, and the two can not be mixed together.