| The"source-sink"process of sediment is an important part of the global material cycle,and in-depth study of its circulation path and mode is an important way to understand the earth's surface generation process.As the third largest river in the world,the"source-sink"effect of the Yangtze River has a strong control and characterization effect on the topography and geomorphology of the surrounding sea area.In the past 30 years,the amount of sediment,entering the sea,from the Yangtze River has continued to decrease,which directly lead to a decrease of the material contribution in the sediment of Zhejiang and Fujian coast.In this context,the material provenance of sediment along the coast of Zhejiang and Fujian include local terrigenous materials(terrigenous materials from rivers and coastal bedrock)and the Yangtze River.Therefore,clarifying the main material provenance of the sediment along the coast of Zhejiang and Fujian is an important content in the field of sedimentology.However,the ocean circulation along the coast of Zhejiang and Fujian is very complicated,which makes it difficult to interpret the provenance signals in the sediments directly.Tidal flats,as the most intense area of sea-land interaction along the Zhejiang-Fujian coast,have the clearest provenance signals carried in the surface sediments.They are an excellent material for studying the main material provenance of the sediment along the Zhejiang-Fujian coast.In Fact,As a reserve land resource,the tidal flat is an effective way to realize the balance of arable land occupation and total amount,and it plays a decisive role in the economic development of coastal areas.This is the practical significance of research on the provenance of tidal flat sediment.The article collected the muddy tidal flat surface sediment from Hangzhou Bay to Fuzhou Bay,as well as the suspended matter and sediment of the Yangtze River and the main rivers of Zhejiang and Fujian(Qiantang,Jiaojiang,Oujiang,Feiyun,Aojiang and Minjiang).Then,detailed study about particle size,magnetism and major elements were carried out on these samples.Main conclusions were as follows:(1)The sediment in the study area are mainly composed of silt and clay,and the content of sand is quite limited;Controlled by the nature of the original rock and its minerals,K and Mg are mostly enriched in the sediments,but Al and Na are mostly depleted;The magnetic properties of the sediment are mainly controlled by magnetite;The difference in the magnetic characteristics of sediments is mainly reflected in the content of magnetic minerals,magnetic domains and coercivity.(2)The Pearson correlation analysis results show that the magnetic characteristics have little relationship with the average particle size.??HIRM?SIRM?MDF20-100m T?(IRM0.1-1T)AF100m T?S-ratio can be used to structure the index to determine the provenance.Though the characteristics of constant elements are greatly affected by the grain size,the factor analysis results indicate that Mg,Si,Ti and Fe can also be used as candidate parameters for structing the index of provenance discrimination.(3)The provenance identification results indicate that the provenance of mud tidal flat deposits in Zhejiang and Fujian include the Yangtze River,coastal bedrock and the Zhejiang and Minjiang River;From Hangzhou Bay to Funing Bay,the sediment is generally affected by the Yangtze River and Zhejiang rivers,and the contributions from the latter are relatively large;the sediment of Aiwan Bay and Xiangshan Port are also affected by the nearby coastal bedrock;The sediment along the coast of Fujian are mainly affected by local materials in Fujian;The contributions from the Yangtze River and Zhejiang rivers are limited in the sediment of Luoyuan Bay and Fuzhou Bay,while the Minjiang River and nearby coastal bedrock are the main provenance;Funing Bay is the area where the main provenance of sediment is converted,so the provenance of its sediment includes the rivers of Zhejiang and Fujian,the Yangtze River and the local coastal bedrock. |
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