Geochemical characteristics and paleoenvironmental significance of lacustrine sediments during the PETM in Nanyang Basin (Central China)

The Paleocene-Eocene Thermal Maximum(PETM)is a global warming event triggered by the massive and rapid release of light carbon into the ocean-atmosphere system, accompanied by accelerated hydrological cycle, ocean acidification, and deoxygenation. Current understanding of the PETM events is primarily derived from marine sedimentary records, whereas terrestrial archives remain relatively scarce, leading to limited knowledge of continental climatic and environmental changes during this period. To address this gap, this study investigates lacustrine sediments from the Nanyang Basin in Central China, spanning the PETM interval. Whole-rock and carbonate fractions were analyzed for major and trace elements, and geochemical proxies—including rare earth element ratios such as Ce/Ce* and LREE/MREE—were employed to reconstruct continental climatic and environmental changes in East Asia during the PETM. The results show significant shifts in all rare earth element indices during the peak-PETM, indicating elevated temperature and increased precipitation, which enhanced both physical erosion and chemical weathering in the Nanyang Basin. These findings demonstrate that the East Asian interior responded sensitively to the rapid climatic and environmental perturbations of the PETM and highlight the potential of rare earth elements as valuable proxies in paleoenvironmental reconstruction.