Dating And Sedimentary Characteristics Of The Xiajiang Group In Southeast Guizhou As Well Evolution Of The South-China Rift System

Xiajiang Group in the east of Guizhou Province and the north of Guangxi Province is a part of the Neoproterozoic rift systems. It below the Changan Group and upon the Sibao Group consists of Precambrian low metamorphic terrisenous clastic sequence interlayer volcaniclastic rocks. The Xiajiang Group can be divided into Jialu, Wuye, Fanzhao, Qingshuijiang, Pinglue and Longli formations from botton to top. Environment changes from epicontinental sea to deep sea. Identify epicontinental sea and deep-sea turbidites. At the base of structural geology, chronology and sedimentary geology, we find out its sedimentary and tectonic paleogeographic characteristics.1. The Xiajiang Group consists of Precambrian low metamorphic terrisenous clastic sequence interlayer volcaniclastic rocks, such as tuff, slate and tuffaceous clastic rock. Sedimentary tectonic, for example waviness, is developed and environment is shore facies and epicontinental sea.2. Base of the data of Qingshuijiang Formation oblique bedding, we see its paleocurrent direction points to SEE.3. As the statistics analysis of the sandstone skeleton particles shows, these clastic deposits were derived from recycled orogenic belt, continental rift volcanic activity and craton.4. On the basis of zircon SHRIMP geochronological study on tuff of the Qingshuijiang Formation Xiajiang Group in the study area, the age of Qingshuijiang Formation is 806±11Ma. So, the Xiajiang Group belongs to Neoproterozoic.5. Now we know, the Xiajiang Group is a part of the Global Neoproterozoic rift systems.