Zircon U-Pb Dating of the Hunandong-granite and Its Caledonian Tectonic Significance,South Jiangxi-East Hunan Province

Hunandong granite located on the border of Hunan and Jiangxi,intruded into the Linyang granite.Based on the investigation of field geology,detailed zircon U-Pb age measurements were done on the Hunandong granite.These zircons have high Th/U ratio with zonal structure,which indicate magmatic zircons.The zircon U-Pb age is(447.2±1.8) Ma,which shows that the Hunandong granite was formed in the late Ordovician period,reflecting the important stage of Caledonian magmatism.According to the result together with other information published,the authors think that the formation of Hunandong granite may be related to the amalgamation and collision between Cathaysian block and Yantze block,providing strong evidence for further understanding the Caledonian magmatism and its geodynamic process in South China.