High-resolution enviromagnetic records of the last deglaciation from Dali Lake, Inner Mongolia

Detailed paleoclimate records during the last deglaciation are highly valuable for understanding rapid climatic changes and mechanisms during extremely variable conditions. High-resolution paleoclimate research in the semi-arid East Asian interior is essential due to its sensitivity to climate variability and importance for human inhabitance. A high-resolution environmental magnetic investigation has been performed on a sedimentary sequence from Dali Lake in central Inner Mongolia, which covers the period of 15.90-11.46 ka. Variable magnetic mineral sources are identified based on integrated rock magnetic analysis of both core sediments and catchment samples, complemented by scanning electron telescope and transmission electron telescope observation and Xray diffraction analysis. The studied core is magnetically divided into four units: Magnetic minerals in Unit 1 (11.83-11.5 m, 15.90-15.32 ka) are mainly sourced from bedrock erosion of basalts in the catchment. This period corresponds to rapid climate fluctuations after the Last Glacial Maximum. In Unit 2 (11.50-9.50 m, 15.32-12.67 ka) and Unit 3 (9.50-8.59 m, 12.67-11.56 ka), pseudo-single domain magnetites from erosion of surface soils are the main magnetic carriers. These two units coincide within time error with the Bolling-Allerod warm period and the Younger Dryas cold period, respectively, and can be correlated with stalagmite and ice core records. Our findings reflect contrasting erosion processes during cold and warm periods in the lake catchment, which were ultimately controlled by climate changes during the last deglaciation. (C) 2016 Elsevier B.V. All rights reserved.