Sr-Nd isotopic compositions of the Changjiang sediments: Implications for tracing sediment sources

• Published in: Science China. Earth sciences Vol. 50; no. 10; pp. 1556 - 1565
• Main Authors: Yang, ShouYe, Jiang, ShaoYong, Ling, HongFei, Xia, XiaoPing, Sun, Min, Wang, DeJie
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.09.2007; State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092, China%State Key Laboratory for Mineral Deposit Research, Nanjing University, Nanjing 210093, China%Departmen of Earth Sciences, The University of Hong Kong, Hong Kong SAR, China%Development Research Center, China Geological Survey, Beijing 100083, China
• Subjects: Changjiang; Freshwater; Geology; Isotopes; provenance; River; rock; sediment; source; Sr-Nd; INW, China, People's Rep., Changjiang Delta; China, People's Rep., Changjiang R; China, People's Rep., Yunnan Prov., Yuanjiang R; Changjiang River; source rock; Sr-Nd isotopes; provenance; sediment
• ISSN: 1674-7313; 1006-9313; 1869-1897; 1862-2801
• DOI: 10.1007/s11430-007-0052-6

The suspended particulate and fine-grained floodplain sediments were collected from the main stream and tributaries of the Changjiang River for Sr-Nd isotopic measurements. The εNd(0) values gradually decrease downstream from -10.8 on average in the upper reaches to -12.3 in the lower reaches, whereas the 87Sr/86Sr ratios increase correspondingly, averaging 0.721899 and 0.725826 respectively in the upper and middle-lower reaches. The compositional variations primarily reflect the complex controls of provenance rocks, chemical weathering, and sediment characters between different catchments, among which the abnormal Sr-Nd isotopic compositions of the Yalong, Fujiang, Tuojiang and Yuanjiang rivers indicate the sediment provenance contributions from the Emeishan Basalt in the upper reaches and the old metamorphic and siliceous rocks in the middle-lower reaches. The Sr-Nd isotopic ratios of the Changjiang sediments can better reflect the average composition of weathered continental crust compared to other major rivers in the world because of the unique source rock types in the Changjiang drainage basin. The recognition of the Sr-Nd isotopic systematics of the Changjiang sediments will contribute to our understanding of the Changjiang evolution history and continental weathering processes during the Cenozoic, and also to reconstructing the paleoenvironmental changes in East China and the marginal seas.