Last Glacial and Holocene fluvial wetland sedimentary stratigraphy: Comparison between Soro-ri and Jangheung-ri archeological sites, Korea

Environmental changes in wetlands during the last glacial reflect the fluvial sedimentary sequences of South Korea. The stratigraphy of the latest Pleistocene sequences in several fluvial drainage basins includes organic mud layers, intercalated in fluvial deposits, particularly including those on the Soro-ri and Jangheung-ri sites of the Miho River and Nam River, respectively. Research methods included analyses of sedimentary facies, 14C dating, and palynology. The post-last glacial maximum (post-LGM) terrestrial sequences are interpreted as responses to fluctuations in fluvial environments. In general, fluvial sequences display cyclicity, including fluvial channel sand and gravel deposits, organic muds of backswamp origin, and overbank flood-deposited muds with intercalated paleosols. Fluvial sedimentary sequences are interpreted to be associated with backswamp organic muds of last glacial age. The age of formation of the lower organic mud layer on the Sorori site is greater than 36 ka BP, and that of the upper organic mud layer ranges from 17 to 12 ka BP. Since 18 ka BP, at the beginning of the post-LGM period, erosional processes became more pronounced. From about 17–15 ka, fluvial depositional processes prevailed, to the end of the last glacial period. The young fluvial sequences, intercalated with organic mud layers, are associated with the late glacial Bølling and Allerød intervals, indicating MIS-1 in Korea.