Composition, Source and Environmental Indication of Clay Minerals in Sediments from Mud Deposits in he Southern Weihai Offshore, Northwestern Shelf of the South Yellow Sea, China

Studying the sedimentary characteristics of the muddy area along the Yellow Sea shelf is of great significance for deepening the understanding of the climate and environment evolution since the last glacial period. Recently, a small muddy area developed in the southern Weihai offshore has attracted a lot of attention. Based on high-resolution grain size, clay mineral, AMS 14 C, and OSL data of sediments from the core WHZK01 in the muddy area, we acquired a new understanding of sedimentary characteristics, sources and paleoclimatic environment during the last 13 kyr. The results show that the core WHZK01 sediments were mainly from the Yellow River and local rivers along the coast. However, the sources varied for different deposition units. The riverbed (before 13 kyrBP) and fluvial plain deposits (13–10 kyrBP) were mainly from local river inputs. The very thin littoral deposits from 10 kyrBP to 8 kyrBP also mainly originate from coastal river inputs, while the littoral-neritic deposits since 8 kyrBP were dominated by the Yellow River materials and partly supplied by the coastal rivers and the island erosion. In addition, five events related with the strong East Asian winter monsoon (EAWM) during the intervals of 13.0–11.0 kyrBP, 10.0–8.2 kyrBP, 7.0–5.0 kyrBP, 3.5–2.5 kyrBP, and 1.2–0.5 kyrBP were identified. Three events related with the enhancement of the EAWM since the middle Holocene have strengthened the transport capacity of the coastal currents of the Shandong Peninsula. Meanwhile, more Yellow River-derived distal sediments were deposited to the southern Weihai offshore and formed wedge-shaped muddy bodies. In short, the ratio of smectite/illite could be used as an effective EAWM indicator since 13 kyrBP on the northwestern shelf of the South Yellow Sea.