Holocene wetland environmental change based on major element concentrations and organic contents from the Cheollipo coast, Korea

Organic and inorganic geochemical and mineralogical analyses from core CL4 drilled in the Cheollipo wetland were carried out to investigate the Holocene Climatic Optimum, the formation of pyrite, and the humidity of the Korean western coast during the Holocene time. Lithostratigraphy, mineralogy, major element concentrations and organic contents of the sediments of the CL4 borehole core indicate that the Holocene Climatic Optimum occurred from about 7400 to 4500 BP, and that pyrite formed in brackish water tidal flat or salt marsh at least during 7400–6400 BP. In addition, sediments coarser in mean grain size and larger in standard deviation corresponded with periods of 8500, 5400, 5000 and 1700 BP. During the periods, the coarse sediments seem to have been delivered by high energy storm events. The periods partially overlap with those of high ratios of Si/Al, Na/Al and Na/Ti. These phenomena indicate that the weakly weathered terrigenous sediments were delivered to the Cheollipo borehole core site by storm events.