Shallow seismic stratigraphy and distribution pattern of late Quaternary sediments in a macrotidal bay: Gunhung Bay, west coast of Korea

Abstract

The shallow seismic stratigraphy of late Quaternary sediments in Gunhung Bay, a macrotidal coastal embayment of western Korea, was investigated by means of analyzing high-resolution seismic profiles and sediment samples. Late Quaternary sediments up to 20 m thick overlie the irregular surface of the acoustic basement. The sediments consist mainly of sands, muddy sands and sandy muds and show a zonal facies distribution. The distribution pattern appears to be largely controlled by the tidal currents in the bay. The sedimentary column above the acoustic basement can be divided into two sequences by a relatively strong mid-reflector which is interpreted as the erosional pre-Holocene surface formed during low sea level. Many V-shaped erosional patterns in this reflector indicate the existence of old tidal channels. The sediments underlying the mid-reflector are interpreted to be semi-consolidated pre-Holocene tidal deposits, presumably deposited during the last interglacial period, while the sediments overlying this reflector represent the late Holocene tidal desposits. Deposition of the late Holocene sediments began probably at about 5000 yrs B.P., when sea level approached its present level.