Sediment geochemistry of Dahu Swamp in the Nanling Mountains, South China: implication for catchment weathering during the last 16,000 years

Abstract

This study emphasizes to testify the potential of geochemical proxies of lacustrine sediments as indicative of past climatic changes since the last deglaciation over the catchment of a small closed lake in South China. Based on the study on the core K02 from Dahu Swamp, a small lake in the eastern Nanling Mountains, we inferred that chemical features of clastic materials, which were mainly derived from the granite weathering crust and transported by surface runoff into this lake, possibly had played an important role in affecting chemical characteristics of the sediments. Wetter climatic conditions would lead to stronger chemical weathering intensity (CWI), resulting in more soluble and mobile elements being easily leached downward in granite weathering crusts and the insoluble ones being enriched in the top materials of the weathering crusts. In contrast, dry conditions would exert a converse influence. Although this study presents a different climatic implication of geochemistry from lacustrine sediments in South China from that in north-central China, the results demonstrate that chemical elements of sediments in the small lake in South China can be utilized to reflect the CWI, which was closely in association with variations in temperature and precipitation in the lake catchment.