| The study area is located in the offshore area of the northeastern Shandong Peninsula (37°00′-38°00′N, 121°30′-123°E). Core NYS-101 (37°42.2279′N, 122°48.248′E)is from the study area.The west part of the North Yellow Sea, that is, the study area, is a main path for sediment from the Yellow River to disperse to the open sea and also an important area of the river-source silt deposition. It is of great significance to understand the dynamics of modern sedimentation process in the coastal zone as well as shelf evolutionary history and the sediment provenance through researches on the element geochemistry of core NYS-101 sediments. Using the data of grain-size distribution, mineral composition and the element geochemistry characteristics of core NYS-101, we discuss the sedimentary environments, sedimentary sources and their controlling factors in the study area. And the main conclusions are as follows:Taking the 6.08 m depth as the boundary,∑REE, LREE, HREE, LREE/HREE,δEu,δCe, (La/Yb)UCC, (La/Sm)UCC, and (Gd/Yb)UCC evidently increase and decrease in 0-18 m interval of core NYS-101. Meanwhile, the ratios of REE to trace elements, such as La/Sc, La/Co, Th/Sc, Th/Co, Zr/Sc, Cr/Th, Ti/Zr, and Ti/Nb also change greatly above and below the boundary.Chondrite and UCC (upper continental crust) normalized REE pattern of the core sediments below the 6.08 m boundary is very similar to that the Yellow River sediments, but 0-6.08 m sediments differ from the River sediments in the pattern.In the geological background, great changes in modern circulation pattern of the North Yellow Sea in the middle Holocene led to large differences in sediment sources for the Shandong Peninsula coast from before the modern circulation pattern. This is the major reason for the evident variations of REE and other inactive trace elements above and below the 6.08 m boundary in core NYS-101.From the early deglaciation to the mid-Holocene before the establishment of the modern circulation pattern, the reciprocating tidal currents via the Bohai Strait carried discharges from the Yellow River to the north Shandong Peninsula where they deposited. After the establishment of the modern circulation pattern, however, river discharges from the west coast of North Korea Peninsula and even a small amount of substances from the Yangtze River were transported by the coastal currents in the West Korea Bay and the warm currents of the Yellow Sea into the study area. |
