Middle Holocene environmental change in central Korea and its linkage to summer and winter monsoon changes

Abstract

To trace the surficial responses of lowlands to past climate change, we investigated δ13C in total organic carbon (TOC), C/N ratios, magnetic susceptibility (MS), and silicon (Si) intensity (directly proportional to concentration) in wetland sediments collected from the Gimpo area of central Korea, covering 6600–4600calyrBP. Two organic layers with high TOC%, negatively depleted δ13CTOC values (−27 to −29‰), low MS values, and low Si intensities were found at 6200–5900 and 5200–4800calyrBP, respectively. These middle Holocene wet periods corresponded to relatively intensified summer monsoon and solar activity periods. The intervening dry period (5900–5200calyrBP) with high MS, high Si, and low TOC% corresponded to an intensified dust-activity interval and stronger winter monsoon. This multi-centennial climatic fluctuation of wet periods (6200–5900calyrBP and 5200–4800calyrBP) and an intervening dry period (5900–5200calyrBP) in central Korea was more synchronous with climate change in the arid inner part of China than with that in South China, suggesting possible strong high-latitude-driven climatic influences (e.g., North Atlantic cooling events) during the middle Holocene.