Holocene development of the Yellow River subaqueous delta, North Yellow Sea

High-resolution seismic profiles from the North Yellow Sea reveal a 20-40-m-thick subaqueous clinoform delta that wraps around the eastern end of the Shandong Peninsula, extending into the South Yellow Sea. This complex sigmoidal-oblique clinoform, containing an estimated 400 km(3) of sediment, overlies prominent relict transgressive surfaces. The nearshore topset of the clinoform, <30-m water depth, has a much less than1:1000 gradient, with high sedimentation rates (Pb-210) similar to 6-12 mm/year. Foreset beds (30-50 m) dip seaward at a steeper gradient (2:1000) and have sedimentation rates similar to 3 mm/year. Bottomset strata, in water depths >50 m, contain less than 1 m of Holocene sediment, with low sedimentation rates, < 1 mm/year. In contrast to other clinoforms, the Shandong clinoform appears to be a compound subaqueous deltaic system, with what we interpret to be proximal and distal phases of clinoform development. The underlying proximal sequence formed proximally between similar to 11 and 9.2 ka in response to a temporary pause in the rapid postglacial sea-level rise after the meltwater pulse I B (MWP-1B) and increased discharge from the Yellow River to the North Yellow Sea due to intensification of the summer monsoon. A flooding surface appears to separate the proximal and distal phases, corresponding to the next rapid sea-level rise 9.5-9.2 ka BP (MWP-1C). Since 9.2 ka BP, an overlying distal sedimentary sequence has accumulated, reflecting the back-stepping and shifting river mouth westward to the Gulf of Bohai. Some inputs from coastal erosion and nearby small streams may be locally important. Along-shore transport, cross-shelf advection, and upwelling in the North Yellow Sea have reworked post-LGM sediment and have helped maintain the morphology of the clinoform in the Shandong mud wedge. (C) 2004 Elsevier B.V. All rights reserved.