Changes in detrital sediment supply to the central Yellow Sea since the last deglaciation

초록

The sediment supply to the central Yellow Sea since the last deglaciation was uncovered through clay mineralogy and geochemical analysis of core 1 lYS-PCL14 in the Central Yellow Sea Mud (CYSM). The core can be divided into four units based on the various proxies, such as grain size, clay mineralogy, geochemistry, and Sr and Nd isotopes: Unit 4 (700-520 cm; 15.5-14.8 ka), Unit 3 (520-310 cm; 14.8-12.8 ka), Unit 2 (310-130 cm; 12.8-8.8 ka), and Unit 1 (130-0 cm; < 8.8 ka). Unit 2 is subdivided into two subunits, Unit 2-2 (310-210 cm; 12.8-10.5 ka) and Unit 2-1 (210-130 cm; 10.5-8.8 ka), according to smectite content. Comparison of the clay mineral compositions, rare earth elements, and ENd indicate distinct provenance shifts in core 1 lYS-PCL14. Moreover, the integration of clay mineralogical and geochemical indices show different origins according to particle size. During the late last deglaciation (Units 3 and 4, 15.5-12.8 ka), Unit 4 sediments originated from all potential provenance rivers, such as the Huanghe, Changjiang, and western Korean rivers, while the source of coarse sediments changed to the Huanghe beginning with Unit 3. Fine-grained sediment was still supplied from all rivers during the deposition of Unit 3. Early Holocene (Unit 2) sediments were characterized by oscillating grain size, clay minerals, and moderate ENd values. In this period, the dominant fine-sediment provenance changed from the Huanghe to the Changjiang, whereas coarse sediments most likely originated from western Korean rivers. The Unit 1 CYSM sediments were sourced primarily from the Changjiang, along with minor contributions from the western Korean rivers. Possible transport mechanisms concerning such changes in the sediment provenance include paleo-river pathways, tidal stress evolution, and the development of the Yellow Sea Warm Current and coastal circulation systems, depending on the sea level fluctuations.

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