Late Quaternary lowstand wedges on the shelf margin and trough region of the Korea Strait

High resolution sparker profiles collected from the Korea Strait reveal a distinct pattern of stacked progradational sedimentary wedges on the shelf margin and trough region. These sedimentary wedges comprise a succession of three distinct units (A lower, B middle, C upper unit), bounded by erosional unconformities, and their internal structures show well-stratified, complex sigmoid-oblique types. The isopach map shows that the wedges thicken seaward and their landward limit is in about 100-120 m water depth. According to the internal structure, distribution pattern and radiocarbon dates, these sedimentary wedges are interpreted to have been formed during the glacioeustatic sea-level lowstands. Multiple falls of sea level during the late Quaternary, coupled with high sediment discharge from the paleo-Nakdong River system, resulted in the formation of thick lowstand wedges. Three intervals of wedge building are recorded; the youngest one (unit C) is interpreted to mark the last glacial period, while the middle one (unit B) represents the lowstand period before the last interstadial.