PROVENANCE STUDY BY U-Pb DATING OF THE DETRITAL ZORCONS IN THE YANGTZE RIVER

Four major U-Pb age groups of detrital zircons are recognized in the modern Yangtze River sediments. They are 200~300 Ma, 400~500 Ma, 750~850 Ma and 1 800~2 000 Ma respectively with 200~300 Ma and 750~850 Ma dominating. Most grains studied are granitic zircons with the Th/U over 0.3. The overlap and similarity analysis of all the samples are in an excess of 0.6. It means that all the samples have the similar U-Pb ages. By comparison of the U-Pb age patterns with the potential source areas of Qiangtang Block, Yidun Volcanic Arc, Songpan-Ganze basin, Yangtze Craton, Qinling orogen and Dabie orogen, it is found that the four age groups mentioned above appeared in almost all the regions except the Qiangtang Block and Yidun Volcanic Arc, hence it is hard to distinguish the final source by U-Pb dating. Meanwhile, the U-Pb age patterns of the Red River and Mekong River sediments are close to those of the Yangtze River, suggesting that the U-Pb dating of detrital zircons can not work well in the Yangtze River as there are no exclusive age indicators. Other methods should be used for seeking conclusions.