Abstract:

 Qianzhong Uplift, an EW gentle uplift, formed in the Late Cambrian period under the control of the Yunan movement. Its evolution went through a transformation stage from underwater to land uprisings, and the Duyun movement caused the transformation between the two uprising stages. The comparison of the sedimentary lithofacies and paleogeography shows that the transformation began in the Late Ordovician Jiancaogou sedimentary stage, at the time of the occurrence of Duyun movement, and its peak developed from the Late Ordovician Wufeng stage to the Early Silurian Longmaxi stage. During the Guangxi movement, Qianzhong Uplift was compressed by YunnanGuizhouNorth Vietnam land mass from south to north and by the remote effect caused by convergence and collision between Cathaysia block and Yangtze plate from southeast, which caused the two types of geological structures survived simultaneously in Qianzhong Uplift and its surrounding areas. They are the EW structures represented by Qianzhong anticline and WudangErbi syncline, and the SN structure represented by Majiang anticline, respectively. Then, the Qianzhong Uplift as an independent tectonic unit disappeared. It connected into a joint development period with the “Jiangnan ancient land”. The Dongwu movement and the Emeishan basalt eruption changed the EW trending paleogeographic frame of the deposition under the control of Qianzhong Uplift to nearly northsouth pattern of sedimentary paleogeography. Thereby the tectonic evolution of Qianzhong Uplift was completely integrated with the Upper Yangtze region, indicating an end to the evolution of Qianzhong Uplift. The zircon UPb age of lamproite in the southern edge of the boundary ZhenyuanGuiyang fault in Qianzhong Uplift is 2613±80 Ma, which is a good indicator of the ending time of the Qianzhong Uplift being an independent unit.

Key words: Qianzhong Uplift, tectonic movement, UPb dating, structural characteristics, tectonic evolution