Shifting sediment sources track environmental changes since the last glacial period: Evidence from sediment records in Chaohu Lake, eastern China

Understanding sediment routing systems and source-to-sink processes in sedimentary basins is crucial for deciphering basin depositional history and paleoenvironmental changes. While significant progress has been made in studying sediment provenance from rivers, oceans, and Loess deposits, lake sediment provenance studies remain relatively scarce particularly in eastern China, which constrains our ability to accurately interpret climate signals through sediment source analysis and basin evolution. This study systematically analyzed rare earth elements (REEs) in the long drill core LZK1502 from Chaohu Lake, eastern China. The objective was to identify the characteristics and influencing factors of REE variations since 35.7 ka BP (before present, where present = 1950 CE) and explore the relationship between sediment sources and environmental changes. The results show that REEs are enriched in light REEs and depleted in heavy REEs, with moderate to slight negative Ce and Eu anomalies. REE compositions are closely linked to grain size, chemical weathering, and environmental changes. Climatic conditions and geological factors indicate that environmental changes significantly influenced the sediment provenance of Chaohu Lake. During the last glacial period, when the climate was predominantly cold and dry, sediments were primarily derived from terrigenous clastic materials weathered from surrounding sedimentary rocks. In the Holocene, the dominant sediment source shifted to weathered clastic material from granite and volcanic rocks as the lake area expanded. During the significant expansion periods of Chaohu Lake, weathered volcanic material from the Lujiang-Zongyang volcanic basin became the primary source of sediments by long-distance transport. In contrast, during periods of moderate expansions, when the lake area contracted, medium-distance weathering products from granite in the Northern Huaiyang volcanic belt became the dominant source. These findings contribute to a deeper understanding of the provenance-climate relationship and offer new insights into paleoclimate reconstruction and lake evolution in the East Asian monsoon region.