Sedimentary architecture of the Holocene mud deposit off the southern Shandong Peninsula in the Yellow Sea

Newly acquired high-resolution seismic profiles reveal a nearshore and an offshore mud depocenter offthe southern Shandong Peninsula in the Yellow Sea. The nearshore depocenter is distributed in bands along the south coast of Shandong Peninsula. The offshore depocenter is part of the distal subaqueous deltaic lobe, which deposited around the southeastern tip of the Shandong Peninsula. Between the two depocenters is a linear depression. The mud deposits directly overlie the postglacial transgressive surface and can be divided into lower and upper units by the Holocene maximum flooding surface. The nearshore and offshore units display different seismic structures. The lower unit of the nearshore deposit exhibits basal onlap, whereas the upper unit is characterized by progradation. The lower and upper units of the offshore deposit display distinct acoustic features. The lower unit has low-angle aggradation with internal reflectors generally dipping seaward and truncated by the Holocene maximum flooding surface, whereas the upper unit is characterized by aggradation and progradation landward rather than seaward. Results of geochemistry analysis of QDZ03 sediments and mineral analysis of WHZK01 sediments suggest that the nearshore deposit and the lower unit of the offshore deposit are derived from the proximal coastal sediments of the Shandong Peninsula and the Huanghe (Yellow) River sediments. The upper unit of the offshore deposit is mainly Huanghe River-derived. The lower unit of the mud deposit represents a post-glacial transgressive system tract according to dates of core QDZ03, and the upper unit represents a highstand system tract from middle Holocene to the present. These results will be of great significance to further understanding of the transportation of the Huanghe River sediments into the Yellow Sea and the spatial distribution of the subaqueous delta.