LA-ICP-MS U-Pb ages and Hf isotopic compositions of detrital zircons in the sediments of the Nujiang River, Yunnan Province, and their geological significance

In this paper, LA-ICP-MS technology was used to perform U-Pb dating and analyze Lu-Hf isotopic composition. U-Pb ages of the detrital zircons in the sediments of the Nujiang River can be divided into 6 groups: 50~74Ma, 84~235Ma, 275~413Ma, 451~569Ma, 657~1429Ma and 1602~3436Ma, with the most important age populations being 50~74Ma and 84~235Ma. The ages of 50~74Ma reflect the history of the subduction and the closure of the Neo-Tethys Ocean, and the age peak of ca.65Ma reveals the main collision stage between India and Eurasian continents. The 84~235Ma might reveal the evolution of the Meso-Tethys Ocean, and the age peak of ca.110Ma is the geological record of the post collisional stage between the Qiangtang block and the Lhasa block. A comparison of the U-Pb ages distribution with that of the Qiangtang block suggests that sediments of the Nujiang River are not derived from the Qiangtang block. In addition, the εHf(t) values and the two-stage model ages of the detrital zircons from the Nujiang River range from -18.7 to +11.7 and from 0.65Ga to 4.05Ga, respectively. Meanwhile, εHf(t) values of the Mesozoic detrital zircons range from -16.4 to +2.9, which is consistent with the data from the Middle Lhasa block and the North Lhasa block.