Holocene climatic and environmental changes recorded in Baahar Nuur Lake core in the Ordos Plateau, Inner Mongolia of China

A 5.3 m lake core was drilled in Baahar Nuur Lake in the Ordos Plateau, and measurements of mean grain size, organic δ ¹³C (δ ¹³C_org), organic carbon content (TOC), C/N, carbonate content, carbonate δ ¹³C (δ ¹³C_car) and δ ¹⁸O (δ ¹⁸O_car) were conducted for retrieving the Holocene chronosequence of climatic changes based on 15 AMS ¹⁴C dates. The record documented four major stages of climate change in the Ordos Plateau: (IV) a cold and dry condition before ∼7.65 ¹⁴C ka BP; (III) a warm and humid stage between ∼7.65 and ∼5.40 ka BP; (II) a generally drier and cooler climate since ∼5.40 ka BP with two humid events occurring from ∼4.70 to ∼4.60 ka BP and from ∼4.20 to ∼3.70 ka BP, and (I) a dry climate characterized by complete desiccation of the lake after 3.70 ka BP. Stage III can be further divided into three sub-stages: (IIIa) a warm and humid episode from ∼7.65 to ∼6.70 ka BP, (IIIb) a warm and relatively dry episode from ∼6.70 to ∼6.20 ka BP, and (IIIc) the magthermal and maghumid episode of the Holocene from ∼6.20 to ∼5.40 ka BP. Supported by the National Natural Science Foundation of China (Grant Nos. 40025105, 40331102, 40421101 and 40671184), US National Science Foundation (Grant No. NSF-ESH04-02509), Ministry of Science and Technology of China (Grant No. G2000048701) and National Geographic Ministry of Society (Grant No. NGS-6938-00)