摘要
The stratigraphic sequence of E’bian Group in Western Yangtze Block is a debatable topic and its age has not yet been constrained by geological chronology for a long time.So,in this paper through the composite analysis of lithological characteristics,sedimentary sequences and their contact relations with its formation or intervals of the Proterozoic E’bian Group in the Western Yangtze Block,the strata location of the Lanbaoping Formation in E’bian Group was determined preliminarily.It should be put in the upper original E’bian Group,representing a new beginning of tectonic cycle and it is not a part of the E’bian Group.The obtained,for the first time,zircon SHRIMP U-Pb age of about(779.3±15.7) Ma from the Lower Lanbaoping Formation volcanic tuff proved it to be the Neoproterozoic,not the mid-Proterozoic.Two single-particle zircon SHRIMP U-Pb ages of about(2737±30) Ma and(2480±29) Ma demonstrate that an old Neoarchean crystallized base may have existed in E’bian-Jinkouhe District in the Western Yangtze Block.These results will contribute to the further research on the E’bian Group in the Western Yangtze Block.