Spatial and temporal variation of typhoon-induced coarse-grained sediments in the muddy inner continental shelf, SE Korea

To document the spatial and temporal variation of typhoon-induced coarse-grained sediments on the muddy inner continental shelf of the southeast Korea, we analyzed the sedimentary facies, ichnofacies, and ¹⁴C dating of 8-m-long six cores obtained from the continental shelf at water depths of 35–55 m. The mud deposits on the inner continental shelf represent the Nakdong subaqueous delta accumulation during the Holocene sea-level highstand. Typhoon-induced deposits consist of coarse-grained sandy and shelly sediments with a sharp lower contact. The upper contact is slightly deformed. Sedimentary records of the typhoon-induced coarse-grained sediments are well preserved on the shallower depocenter with high sedimentation rate in the Nakdong subaqueous delta. Grain size and thickness of the typhoon-induced deposits are increased from mid to late Holocene due to the different typhoon intensity and pathway based on the ¹⁴C dating and grain size analysis results. In addition, the Skolithos ichnofacies are dominated by high turbidity settings related to the typhoon-generated high turbulent conditions and differ from Planolites ichnofaices under fair-weather conditions. Historical records of typhoon-driven energetic conditions provide to analyze essential information of wind speeds, wave heights, coastal currents, and atmospheric pressure for predicting for future energetic conditions in the continental shelf.