DISTRIBUTION PATTERN OF REES IN THE INNER-SHELF MUD AREA OF EAST CHINA SEA

Thirty surface samples were collected from the inner-shelf mud areas of the East China Sea. The compositions of rare earth element(REEs), major and minor elements, TOC, CaCO₃ and grain size were analyzed for bulk samples. With the results, we discussed in this paper the factors controlling the distribution of the REEs. Results show that the contents of ΣREEs in the inner shelf mud deposits of the East China Sea range from 182.8~221 μg/g with an average of 206.5 μg/g, significantly higher than that in the loess, Yellow River and Yarlung Tsangbo River sediments, but similar to that of the Yangtze River and Oujiang River sediments. Chondrite-normalized REE patterns and (La/Yb)_N ratios show that light REE (LREE) are enriched relative to heavy REE (HREE) in sediments with a very strong negative δEu value. Upper continental curst-normalized REE patterns show that the REE of the mud deposits have little fractionation with the UCC and a tetrad pattern of REE were observed in the mud sediments. The weak correlation between REEs and grain size, TOC, CaCO₃ indicate that those factors are not critical to the distribution of REEs. The elements ratios and the UCC-normalized pattern of REE suggest that the sediments in the study area are mainly from the Yangtze and Oujiang Rivers.