呼伦贝尔草原小型湖泊沉积物元素地球化学记录及其古环境意义

Element Geochemical Records of Sediments from Small Lakes in the Hulun Buir Grassland and Their Paleoenvironmental Significance

摘要: 利用XRF岩芯扫描技术，获取了内蒙古呼伦贝尔草原西南边缘小型封闭湖泊阿然吉诺尔湖的沉积物岩芯高分辨率的元素地球化学记录，并结合AMS¹⁴C测年建立了可靠的年代框架。通过沉积物的元素地球化学记录进行综合分析与对比，重建了该区域末次冰消期以来的气候环境演变序列。研究结果表明：14.3~9.3 ka BP，气候特征总体上为寒冷干燥，但有向暖干变化的趋势。9.3~5.9 ka BP，总体气候特征较为温暖湿润。5.9~1.6 ka BP，早期气候呈现逐渐干旱化的趋势，后期保持温暖湿润且气候变化更加和缓。1.6 ka BP至今，气候波动较为剧烈，大致经历了冷干到暖湿再到冷干的过程。该高分辨率记录显著揭示了8.2 ka BP和4.2 ka BP等百年–千年尺度的气候突变(干旱)事件，表明阿然吉诺尔湖作为呼伦贝尔草原上的小型封闭湖泊对全球气候事件存在敏感响应。

Abstract: Using XRF core scanning technology, high-resolution elemental geochemical records of sediment cores from Aranjinuoer Lake, a small closed lake on the southwestern margin of the Hulun Buir grassland in Inner Mongolia, were obtained, and a reliable dating framework was established in combination with AMS¹⁴C dating. Through the comprehensive analysis and comparison of the elemental geochemical records of the sediments, the climatic and environmental evolution sequence since the last deglaciation in the region was reconstructed. The results show that: At 14.3~9.3 ka BP, the climate characteristics are generally cold and dry, but there is a trend of warm and dry change. At 9.3~5.9 ka BP, the overall climate is warm and humid. At 5.9~1.6 ka BP, the early climate showed a trend of gradual drought, and the later period remained warm and humid and the climate change was more moderate. From 1.6 ka BP to now, the climate fluctuation is more intense, and it has undergone a process from cold dry to warm wet and then to cold dry. The high-resolution record significantly reveals 100-millennium-scale climate abrupt (drought) events such as 8.2 ka BP and 4.2 ka BP, indicating that Aranjinuoer Lake, as a small closed lake on the Hulun Buir grassland, is sensitive to global climate events.