Sediment transport and depositional hydrodynamics on the eastern Korean continental margin revealed by surface sediment granulometry

ABSTRACT Terrigenous sediments are transported from coastal areas and shelves to deeper continental margins by multiple processes. Understanding these processes is critical for evaluating the ecological impacts of fine‐grained sediment deposition and predicting future changes in sediment dispersal under rapid climate change. This study investigated sediment transport and hydrodynamic controls on the eastern Korean continental margin, characterised by a wave‐dominated coast and a slope shaped by contour currents and complex morphology. Surface sediment granulometry and grain‐size end‐member (EM) analysis distinguished three regimes: a wave‐dominated shelf and upper slope, a middle to lower slope influenced by bottom currents and a deeper slope marked by hemipelagic settling. Seaward‐fining trends subparallel to isobaths reflected sorting by declining wave energy, while deviations in the sand–mud transition to greater depths occurred near transgressive lags and stream mouths. A shift from wave‐induced erosion to bottom‐current‐driven deposition coincided with clay enrichment (>10%), which enhanced cohesion and produced distinct linear trends between sortable silt (SS) mean size and proportion. Variations in SS mean size across steeper and protruding slopes highlighted the topographic modulation of the southward‐flowing North Korean Cold Current. Five grain‐size end members were identified, corresponding to relict deposits, riverine bedload sands, suspended coarse and fine silts, and aeolian dust. Their abundance ratios quantitatively capture sediment fractionation effects induced by waves and bottom currents across the shelf and slope. This study demonstrates that integrating granulometric parameters with EM analysis provides a robust framework for identifying dominant sedimentary processes and assessing how seafloor morphology and oceanographic conditions regulate sediment dynamics along continental margins.