Rare earth element compositions and provenance implications:A case from sediments of the Mulanxi River Estuary and surrounding sea area

The Mulanxi River in Fujian Province is a typical tide-dominated mountainous river in the southeast coast of China. The rare earth element (REEs) is adopted for provenance study and paleoenvironmental reconstruction in this paper.We investigated REE composition and provenance implications from both the weathering profile and the surface sediments of the Mulanxi River and its adjacent offshore areas. There the surface sediments are dominated by clayey silt with a very similar UCC normalized REE pattern and without obvious REE fractionation. Some REE index like ΣREE and δEu are related to the grain size and chemical weathering intensity. The (La/Yb)_N-ΣREE/Al diagram is used to identify the sediment provenance in the study area.REE compositions from smaller rivers in Zhejiang and Fujian Provinces are significantly different from those of the Changjiang River. The sediments in the adjacent area of Xinghua Bay mainly come from the inner shelf mud of the East China Sea, and the fine suspended sediment of the Changjiang River carrying up by the Zhejiang and Fujian coastal current can be found in Quanzhou Bay and surrounding area. Since the sediments in the surrounding area of Quanzhou Bay are coarse, the REE composition shows strong spatial inhomogeneity due to the dilution by quartz.