Abstract:

The Ganjiang River is the biggest river in Jiangxi Province, which is also one of eight major tributaries of the Yangtze River. In order to investigate the material source of stream sediment in the Ganjiang River, the U-Pb age of detrital zircons from the Ganjiang River (Nanchang Section) were carried out by the LA-ICP-MS analysis technique. One hundred and twenty three spots are effective among the 140 analytical spots. The data suggest that zircons are mainly composed of 7 age stages, including 134-197 Ma, 221-290 Ma, 386-484 Ma, 520-625 Ma, 727-895 Ma, 980-1,110 Ma and 2,502-2,861 Ma, respectively, corresponding to the known tectonic-magmatic thermal events, i.e., Yanshanian Movement, Indosinian-Hercynian Movement, Caledonian Movement, Jinning Movement, Lüliang Movement. The Th/U ratios of most zircons with distinct magmatic zoning are more than 0.4, indicating that they are of magmatic origin. The result reveals that the zircons of 134-197 Ma mainly come from Southern and Central Jiangxi, Western Fujian and Northern Guangdong area. The Indosinian zircons of 221-290 Ma mainly stem from Southern Jiangxi and Hercynian zircons from Central Jiangxi and Jiuling area. The zircons of 386-484 Ma mainly come from Southern and Central Jiangxi and some are from Northwestern Jiangxi Province. The zircons of 520-625 Ma could be judged that they come from Southern Jiangxi. The zircons of 727-895 Ma are mainly from Jiuling area. The zircons of 980-1,100 Ma and 2,502-2,861 Ma mainly come from Southern Jiangxi and Northern Guangdong in Cathaysia Block. Therefore, the main material resource of the Ganjiang River could be effectively constrained by the U-Pb age of the detrital zircon from stream sediment.

Key words: stream sediment, detrital zircon, U-Pb chronology, provenance analysis, the Ganjiang River