沙漠古气候重建对于了解区域古气候演变具有重要意义。通过以巴丹吉林沙漠东南缘巴润宝日陶勒盖（BRBG）剖面为研究对象,进行全样地球化学、分组分分粒级元素地球化学及Sr同位素分析,重建该地区末次冰期期间（66.8~41.0βka）的气候演化模式。研究表明：66.8~41.0βka呈现残留组分高Sr/Ca值、酸溶组分及残留组分低Ba含量特征,指示化学风化增强及湖泊补给量增加,反映暖湿气候特征。微量元素变化特征指示沉积物细粒组分中的微量元素指标对气候的敏感度高于粗粒组分。Sr同位素结果显示酸溶组分中⁸⁷Sr/⁸⁶Sr值在66.8βka附近达到最大值,可能与湖水盐度升高相关。此外,几乎所有指标均指示在41.0βka前后存在一次气候突变事件,研究认为巴丹吉林沙漠东南缘41.0βka前后从暖湿突变为干冷气候可能是该时期的西伯利亚高压系统增强所致。

Reconstructing the desert paleoclimate is critical for understanding paleoclimate evolution. As the third-largest desert in China, the Badain Jaran Desert’s mega dune is the highest in China and the world and unique for its crowded mega dunes. This region’s geology and environmental information are challenging to acquire. By using innovative methods and techniques to study the Badain Jaran Desert’s climate change, research will significantly influence climate studies in the northwest arid area and even East Asia. The climate evolution model during the last glacial period (66.8-41.0 ka) in the Barunbaoritaolegai (BRBG) section in the southeastern margin of the Badain Jaran Desert was reconstructed using whole-sample geochemistry, granular-scale element geochemistry, and Sr isotope analysis. During 66.8-41.0 ka, the residual components showed high Sr/Ca values, whereas acid-soluble and residual components showed low Ba contents, indicating enhanced chemical weathering and increased lake supply, reflecting the characteristics of a warm and humid climate. The trace element changes indicate that trace elements in the fine grain components of sediments are more sensitive to climate than the coarse ones. Although the geochemical indices from the entire sample show little obvious feedback, the other innovative technique used in this study suggests higher efficiency and more sensitivity to environmental variation. Therefore, this approach could be used in future studies on climate and environmental variation. Based on the experimental outputs, the K and Sr concentrations in the residual components of fine fraction (<125 μm), the Sr/Ca values of residual components of fine fraction (<125 μm), the K concentrations in the acid-soluble components of the coarse fraction (>125 μm), and the Al concentrations in both acid-soluble and residual components of the coarse fraction (>125 μm) are the typical sensitive chemical indicators of climate change. The research group found that fine-sized fractions in the sediments are sensitive to climate change, which is an ideal media to reflect environmental vibration. By introducing novel ideas to climate-related research, the team discovered that Ba variations in acid-soluble fractions are highly sensitive, whether in fine or coarse grain-sized sediments. The⁸⁷Sr/⁸⁶Sr ratio of sediments from the inland lake is a critical indicator of chemical weathering intensity. The ratio change in acid-dissolved components indicates a change in strontium in the deposition area, whereas the ratio change in residual components reflects a change in strontium in the source area. The opposite trend is evident for the strontium ratio, showing that the response of different sediment components to chemical weathering is different in the provenance and sedimentary regions. Sr isotope results show that the ⁸⁷Sr/⁸⁶Sr value reached a maximum at ~66.8 ka, which could be related to the increase in lake water salinity. Furthermore, most indicators show a sudden climate change at ~41.0 ka, and the study indicates that the abrupt change from warm wet climate to dry cold climate at ~41.0 ka in the southeastern margin of Badain Jaran Desert might be caused by the enhancement of a Siberian high-pressure system in this period.