• 责任者：Yang Shouye (State Key Laboratory of Marine Geology ; School of Ocean and Earth Sciences ; Tongji University ; Shanghai 200092 ; China) ; Li Chao
• 刊名：Quaternary Sciences
• 出版年：2013
• 卷期：33(4)
• 关键词：物源分析 ; provenance analysis ; 现代沉积 ; recent deposit ; 长江 ; Yangtze River
• 页码：p.645-655
• 图表：9 illus., 41 refs.
• 分类号：1400
• issnNo：ISSN1001-7410
• isbnNo：CN11-2708/P

     The key for sediment source to sink study of the Changjiang River（Yangtze River）is to reveal the chemical composition of the Changjiang River sediment and to understand the compositional variations at different spatial and temporal scales,which are also important for the studies of land-sea interaction in the eastern marginal seas and of tectono-climatic evolutions of the Changjiang River.In this study,a total of 9 suspended and 25 fine-grained floodplain sediment samples were collected from the upper Jinshajiang River in Lijiang to near the Changjiang River mouth in March and April of 2003 and 2004,July and August of 2008,and July of 2009.In addition,51 suspended sediment samples were taken from the lower Changjiang mainstream near Nantong during the period from April 2008 to April 2009,with each sampling interval of every week.In the State Key Laboratory of Marine Geology,the analyses of grain size and elemental compositions were carried out on these samples.The main purpose of this paper is to investigate the heterogeneity of sediment geochemical composition of the Changjiang River sediments with emphasis on rare earth elements（REE）and other geochemical parameters.In particular,the REE fractionation parameters including（La/Yb）UCC,（La/Sm）UCC,（Gd/Yb）UCC,Ce and Eu anomalies,ratios of Al/Ti and Zr/Rb,and chemical index of alteration CIA were discussed in this study.The REE compositions of the seasonal suspended sediments taken from the lower mainstream near the river mouth are quite stable,reflecting the average composition of the fine-grained Changjiang River sediment into the sea.In contrast,the REE compositions exhibit large variations in the floodplain and suspended sediments from the major tributaries and other localities of the mainstream.Chemical speciation analysis can better reflect the REE compositions in the sediments from unique provenances,and reveal the variability of REE fractionation parameters caused by mineral sorting during sediment transport.Compared to REE,the ratios of Al/Ti and Zr/Rb in the suspended sediments are more sensitive to the changes of sediment provenances by minimizing the influences of sediment grain size and mineral fractionations in relation to hydrological sorting.As the averaged mixture of fine-grained sediments weathered from the whole Changjiang River drainage basin,the suspended sediments in the lower mainstream near the river mouth can be used as the modern representative of the Changjiang-derived sediments in the sea.Nevertheless,the dominant provenances of the Changjiang River sediments into the estuary and marginal sea change with seasons,mainly because of the seasonal shifts of monsoon precipitation fronts in the drainage basin.It has to be cautious in using some widely-documented geochemical proxies to reconstruct the source-to-sink pattern of fluvial sediments due to the influences of weathering and sediment transport processes.