Rare earth element composition and provenance implication of sediments in the Central South Yellow Sea since MIS6

Rare earth elements (REE) and grain size in the 0～30 m section of Core SYSC-1 sediments taken from the Central South Yellow Sea were analyzed. Combined with geochronic age dated, the composition characteristics and influencing factors of REE in sediments were studied, and the changes in their material sources were discussed. The vertical distribution of ∑REE varied greatly from 111.66 to 231.12μg/g, and the average value is similar to loess REE in China. A certain correlation between ∑REE and grain size variation was revealed. The value of (La/Yb)_N, (Gd/Yb)_N, and (δEu)_N were less affected by particle size, which effectively reflected the provenance of sediments. Compared with the sediments of surrounding rivers, the distribution of (La/Yb)_N and (δEu)_N in scatter map are close to those of the Yellow River and the Yangtze River, but significantly different from those of the rivers in the Korean Peninsula. The provenance results of REE discriminant function (DF) show that the borehole experienced a sudden change in provenance during MIS6 from the Yangtze River source (27.98～30 m) to the Yellow River source (24.24～27.98m). During the MIS5.5—MIS5.1, shallow shelf cold water mass deposits (24.24～16.98 m) were developed. They were mainly composed of fine-grained sediments from the source of the Yangtze River, which were carried out northward by the ancient Yellow Sea warm current, and deposited near the cold vortex area. During the low sea level period from MIS5.1 to MIS1 (16.98～3 m), a set of littoral and shallow sea, estuarine/tidal flat and delta deposits were mainly developed. With the rapid decrease of sea level, the shelf accommodation space was reduced, which led to the shift of estuaries of the Yellow River and the Yangtze River towards shelf area, and the Yellow River sediments controlled the northern area of the South Yellow Sea. In the middle and late MIS1, the formation of the Shandong Peninsula coastal current mainly confined the Yellow River sediments to the western part of the South Yellow Sea, while the Yellow Sea warm current transported the fine particles of the Yangtze River source to the cold vortex area near the core SYSC-1 in the southwest of Jeju Island. In general, the sedimentary evolution of the central area of the South Yellow Sea since MIS6 is a good example of interaction between sea and river in the western Pacific margin. Sea level fluctuations and ocean circulation changes play an important role in the change of provenance.