Recurring tide-dominated sedimentation in Kyonggi Bay (west coast of Korea): similarity of tidal deposits in late Pleistocene and Holocene sequences

Up to 40 m of tidal deposits occur in the inner part of Kyonggi Bay, west coast of Korea (Yellow Sea). A prominent paleosol in the upper part of the succession separates two depositional sequences, of late Pleistocene and Holocene age. Identical tidal facies, including tidal rhythmites, occur within both sequences. The rhythmites in the late Pleistocene sequence demonstrate tidal periodicities ranging from semidiurnal to monthly that are similar to those of the modern tides. The fine-grained texture, accentuated monthly tidal cycles, facies associations, and stratal architecture indicate that the rhythmites are of upper intertidal origin. The predominance of such tidal facies throughout the considerable thickness of both sequences indicates that considerable vertical aggradation occurred and that a tide-dominated (presumably macrotidal) estuarine environment was sustained in Kyonggi Bay throughout the late transgression and early highstand of both the late Pleistocene and Holocene sequences. The broad, shallow shelf and stable tectonic setting of the Yellow and East China seas facilitated the repetition of tide-dominated sedimentation in Kyonggi Bay over several sea-level cycles. The system does not appear to be strongly sensitive to changes in relative sea level or coastal configuration. Ancient sedimentary successions that record repeated episodes of tide-dominated sedimentation must also have formed in settings where the paleogeography changed relatively little between sea-level cycles, and/or that the changes were insufficient to affect the tidal dynamics.