Tidal Flats of the Shinan and Seocheon Areas in Korea: Their Sedimentological and Geoheritage Significance

Abstract:

The tidal flats along the coast of western part of the Korean Peninsula have been developed due to rapid sea-level rise on broad marginal seas during the Holocene. Tidal flats are characterized by large elongate subtidal sand bars and broad intertidal and supratidal mud flats with spring tidal range reaching up to 10 meters. Geomorphic features, surface sediments and core data show that the intertidal flat can be divided into two zones:upper intertidal zone and lower intertidal zone. The upper intertidal zone dips gently seaward with shore-normal tidal creeks, which changes from mud-flat facies to mixed-flat facies with seaward coarsening in average grain size. Dominant sedimentary facies are homogeneous mud (highly bioturbated) and thinly interlaminated sand/mud to coarsely interlaminated sand/mud (wavy and lenticular bedding) showing seasonal bedding.The surface topography of lower intertidal flat is characterized as sand-bar complex migrated landward. The bars are reaching up to 1.5m in height, and shore-parallel tidal creeks are developed between individual bars. Dominant sedimentary facies is sand-flat facies except for mixed-flat facies occurring near boundary of two zones. Broad tidal flats around the islands of the Shinan and Seocheon areas associated with macrotidal range in very shallow epicontinental sea (Yellow Sea) display outstanding geological processes and geoheritage significance, which can be a strong potential World Heritage site.