全新世共和盆地沙地时空演化及其驱动机制

通过分析青藏高原东北部共和盆地现代固定沙丘、半固定-半流动沙丘和流动沙丘的粒度与地球化学元素特征，建立了不同类型沙丘沉积物的理化指标体系，并尝试性地将其用于地质时期沙漠演化研究。同时，结合区域典型风成砂-古土壤剖面的相变特征，探讨了全新世共和盆地沙地的时空演化过程及其驱动机制。结果表明：全新世共和盆地沙地存在多次活化、扩张和固定、缩小，除11.8～10.1 ka为流动沙地以外，其余阶段多在半流动-半固定沙地和固定沙地之间频繁转换，这一变化特征与其相邻的柴达木盆地沙地和青海湖地区环境变化具有良好的可比性。此外，发现沙地环境变化对湿度状况十分敏感，而湿度又受控于区域冬，夏季风的强度，也就是说全新世共和盆地沙地演化是气候变化的产物。

Spatiotemporal Evolution of Sandy Land in the Gonghe Basin during the Holocene Period and Its Possible Driving Mechanism

The physical and chemical indicator system of different types of sand dune deposits was reconstructed by analyzing the characteristics of grain size and geochemical elements from the modern fixed, semi-fixed and semi-shifting and mobile sand dunes in Gonghe Basin, northeastern Qinghai-Tibetan plateau, and it is tentatively applied to the study the desert evolution in geological time. In the meanwhile, combined with variation of the sedimentary facies in typical aeolian sand-paleosol profile, we discussed the spatiotemporal changes of the Gonghe Basin sandy land during the Holocene period, and possible driving mechanism. The results indicate the region experiences the several activation, expansion and fixation, reduction. Specifically, the sandy land was dominated by the mobile dune in 11.8～10.0 ka, while frequently change among semi-fixed, semi-shifting and fixed sandy land were discovered in other periods. These characteristics are well comparative with the environmental change in adjacent Qaidam Basin desert and Qinghai lake region. In addition, we found the sandy land environment is very sensitive to the humid condition which is controlled by the winter and summer monsoonal strength. In other words, sandy land evolution in Gonghe Basin during the Holocene is product of climatic change.