REE partitioning in riverine sediments around the Yellow Sea and its importance in shelf sediment provenance

We sought to identify the characteristics and their controlling factors of rare earth element (REE) fractionation patterns in two chemically partitioned (labile and residual) fractions of Korean (KR) and Chinese riverine (CR) sediments. We also investigated their sediment origins in the Yellow Sea based on REE signatures. The results showed that the upper continental crust (UCC)-normalized REE fractionation patterns were remarkably different for labile and residual fractions, even between KR and CR sediments. Notably, KR sediments in both residual and labile fractions exhibited a striking enrichment of light REEs (LREEs), unlike CR sediments, with no obvious fractionation. Such LREE enrichment is relatively much stronger in the coarse-grained sandy sediments. The peculiar LREE enrichment in both fractions of KR sediments was preferentially linked to grater felsic granitic compositions, compared with CR sediments that were close to those of the UCC (granodiorite with relatively more mafic minerals), consisting of a mixture of various rock types. Application of these REE signatures to the provenance of Yellow Sea sediments provides an important clue to the cause underlying the lack of correlation between the mud budget and the river discharge in Korean coastal regions as well as the ultimate fate of CR sediments. The REE fractionation signals, especially in residual fractions may shed light on the major existing phases affecting REE fractionation as well as the origin of sediments in the Yellow Sea.