EVOLUTION OF LATE QUATERNARY DEPOSITS ON THE INNER SHELF OFF THE SOUTHEASTERN COAST OF KOREA (KOREA STRAIT)

High-resolution seismic profiles and borehole data from the inner shelf off the Nakdong River in the Korea Strait were analyzed to document the stratigraphy and evolution of inner shelf deposits closely related to the post-glacial sea-level rise. The inner shelf sequence consists of three stratigraphic units: transgressive estuarine deposits (Unit III), thin sand layer (Unit II), and Nakdong subaqueous delta (Unit I), from oldest to youngest. 14C age data suggest that the study area became flooded at about 11,000 yr BP and the sea level nearly reached its present position approximately at 6000 yr BP, respectively. Unit III above the acoustic basement consists of estuarine sandy mud and muddy sand including brackish water species of foraminifers deposited during the middle to late stage of post-glacial sea-level rise (11 ?8 ka), whereas Unit II consists of thin sands, as transgressive lag deposits, produced through shoreface erosion during the transgression (8 ka ?6 ka). Unit I consists of recent muds deposited during the last 6000 yr BP when sea level was close to the present level. Recent muds mainly derived from the Nakdong River prograded over transgressive units, forming a Nakdong subaqueous delta.